N. Fonsova, V. A. Dubynin Physiology of higher nervous activity and sensory systems. Physiology of higher nervous activity and sensory systems Cutaneous sensory system
Year of issue: 2009
Genre: Physiology
Format: DOC
Quality: OCR
Description: The textbook “Physiology of sensory systems and higher nervous activity” describes in detail the mechanisms of excitation and inhibition of neurons, conduction of excitation in nerve fibers and synapses of the central nervous system, general and specific physiology of analyzers (encoding information in analyzers, excitation of receptors, three sections of analyzers), modern ideas about human GNI (mechanisms of memory, emotions and motivation, basic forms of mental activity), typological features of GNI, mechanisms of formation of behavioral reactions, systemogenesis, features of human GNI, sleep and dreams, corticovisceral relationships.
A special feature of the textbook is the presence in it of original (author's) classifications of conditioned and unconditioned reflexes, instincts, needs, etc., definitions of higher nervous activity and mental activity, which will help the reader to study more deeply certain controversial issues.
The textbook “Physiology of sensory systems and higher nervous activity” consists of three parts and an appendix.
The first part gives a brief description of the analytical and synthetic activity of the brain, provides definitions of the concepts of higher and lower nervous activity, mental activity, psyche and consciousness, reveals the concepts and examines the stages of the process of analysis and synthesis, describes the neural organization of the cerebral cortex, and the localization of functions in the cortex.
The second part outlines the classical ideas about analyzers according to the theory of I.P. Pavlov, as well as modern ideas about the general patterns of activity of analyzers (sensory systems), their role in the adaptive activity of the body, describes the functions of individual sensory systems, and the analgesic system of the body.
The third (main) part of the book “Physiology of sensory systems and higher nervous activity” is devoted to consideration of issues related to higher nervous activity: classical and modern ideas about GNI are presented, memory mechanisms, congenital and acquired forms of activity, needs, motivations and emotions, features are described in detail human mental activity, functional states, sleep mechanisms, organization of behavioral reactions.
The application is a guide for students' practical work.
"Physiology of sensory systems and higher nervous activity"
Analytical-Synthetic activity of dose
- General provisions
- Stages of the analysis and synthesis process
- Structural and functional organization of the neocortex
- Localization of functions in the cerebral cortex
General principles of operation of sensor systems
- Concepts
- Classification of sensory systems
- Structural and functional organization of sensory systems
- Properties of sensory systems
- Encoding information in sensory systems
- Regulation of the activity of sensory systems
- Visual sensory system
- Mechanisms that provide clear vision in various conditions
- Color vision, visual contrasts and sequential images
- Auditory sensory system
- Structural and functional characteristics
- Perception of pitch, sound intensity and sound source location
- Vestibular and motor (kinesthetic) sensory systems
- Vestibular sensory system
- Motor (kinesthetic) sensory system
- Internal (visceral) sensory systems
- Cutaneous sensory systems
- Temperature sensor system
- Tactile touch system
- Chemoreceptive sensory systems
- Taste sensory system
- Olfactory sensory system
- Nociceptive sensory system
- Structural and functional characteristics
- Types of pain and methods of its study
- Analgesic (antinociceptive) system
Story. Research methods
- Development of the reflex concept. Neurosm and nerve center
- Development of ideas about GNI
- GNI research methods
- Congenital forms of body activity
- Acquired forms of behavior (learning)
- Characteristics of conditioned reflexes and their significance
- Classification of conditioned reflexes
- Plasticity of nervous tissue
- Stages and mechanism of formation of conditioned reflexes
- Inhibition of conditioned reflexes
- Forms of learning
- Memory
- general characteristics
- Short-term (electrophysiological) memory
- Intermediate (neurochemical) memory
- Long-term (neurostructural) memory
- Remembering and Forgetting
- The role of individual brain structures in memory formation
- Main types of GNI in animals and humans
- Typological personality options for children
- Basic provisions for the formation of the type of GNI and personality temperament
- The influence of genotype and environment on the development of neurophysiological processes in ontogenesis
- The role of the genome in plastic changes in nervous tissue
- The role of genotype and environment in the formation of personality
- Needs
- Motivations
- Emotions as one of the forms of mental activity
- Types of mental activity
- Electrophysiological correlates of mental activity
- Mental activity and electroencephalogram
- Mental activity and evoked potentials
- Features of human mental activity
- Human activity and thinking
- Mental activity and the second signaling system
- Development of speech in ontogenesis
- Lateralization of functions and mental activity
- Socially determined consciousness
- Conscious and subconscious brain activity
- Concepts and neuroanatomy of the functional state of the body
- Wakefulness and sleep. Dreams
- Sleep and dreams, assessing the depth of sleep, the meaning of sleep
- Mechanisms of wakefulness and sleep
- Hypnosis
- Levels of integrative brain activity
- Conceptual reflex arc
- Functional system of behavioral act
- Basic brain structures that ensure the formation of a behavioral act
- Neuronal activity and behavior
- Motion Control Mechanisms
Physiology of sensory systems
- Determining the field of view
- Determination of visual acuity
- Accommodation of the eye
- Blind spot (Mariotte experience)
- Color vision testing
- Determination of the critical flicker fusion frequency
- Stereoscopic vision. Disparity
- Study of auditory sensitivity to pure tones in humans (pure-tone audiometry)
- Study of bone and air conduction of sound
- Binaural hearing
- Skin esthesiometry
- Determination of taste sensitivity thresholds (gustometry)
- Functional mobility of the tongue papillae before and after eating
- Thermoesthesiometry of the skin
- Determination of the sensitivity of the olfactory sensory system (olfactometry)
- Studying the state of the vestibular sensory system using functional tests in humans
- Determination of discrimination thresholds
- Development of a blinking conditioned reflex to a bell in humans
- Formation of a conditioned pupillary reflex to a bell and to the word “bell” in humans
- Study of bioelectrical activity of the cerebral cortex - electroencephalography
- Determination of the volume of short-term auditory memory in humans
- Memory studies using the method of A.R. Luria (10 words)
- Identification of the predominant type of memory
- The connection between reactivity and personality traits - extraversion, introversion and neuroticism
- The role of verbal stimuli in the emergence of emotions
- Study of changes in EEG and autonomic indicators during human emotional stress
- Changing the parameters of the evoked potential for a flash of light
- Study of the predominant type of temperament using the method of A. Belov (1971)
- Determination of the type of IRR in a person (by psychomotor reaction - taping test)
- Reflection of the semantics of a visual image in the structure of evoked potentials
- Study of the type of GNI using a questionnaire
- Influence of the goal on the performance result
- The influence of situational afferentation on the result of activity
- Predicting human behavior based on determining personality type
- Determination of stability and switchability of voluntary attention
- Study of imaginative thinking using the “exclusion of the superfluous” test
- Determination of the type of mental activity
- Study of types of mental activity according to the method of E.A. Klimov
- Assessing a person’s ability to work when performing work that requires attention
- Determination of personality traits according to N. Eysenck
- The importance of memory and dominant motivation in goal-directed activity
- Study of personality traits to identify functional asymmetries of the brain
- Identification of motor asymmetries
- The importance of dominant motivation in shaping behavior
- The influence of mental work on functional indicators of the cardiovascular system
- The role of reverse afferentation in optimizing the operator’s activity mode at the computer
- Development of a dynamic stereotype in humans
- Automatic analysis of cardiovascular system indicators at different stages of motor skill development
- Analysis of operator learning rate in deterministic environments
- Study of thinking by classifying phrases as proverbs
- Determination of a person's chronotype
- Determination of biological rhythm
- Using a computer to study short-term memory
Ministry of Education and Science of the Russian Federation
Federal State Autonomous Educational Institution of Higher Professional Education
"Russian State Vocational Pedagogical University"
Faculty of Psychology and Pedagogy
Department of PPR
Test
“PHYSIOLOGY OF HIGHER NERVOUS ACTIVITY AND SENSORY SYSTEMS”
Completed by: student gr.
Simanova A.S.
Option: No. 6
Ekaterinburg
Introduction
1. Theories of the formation of a temporary connection of a conditioned reflex
2.Physiology of skin sensitivity
Conclusion
Bibliography
Introduction
Modern pedagogy is based on knowledge of the laws of ontogenesis, not only on the general conditions thanks to which a child becomes a normal person, but also in special developmental circumstances that arise in individual cases, called individual development. These conditions include a complex of natural properties of the body: structure and functioning, the level of mental development and its coordination through education, hygienic standards necessary for the development and functioning of the body.
Physiology is a science that studies the patterns of formation and features of the functioning of an organism in the process of ontogenesis: from the moment of its inception to the completion of the life cycle. As an independent branch of physiological science, age-related physiology was formed relatively recently - in the second half of the 20th century, and almost from the moment of its inception, two directions emerged in it, each of which has its own subject of study, including such a direction as the physiology of the central nervous system. systems.
The purpose of the test is to reveal the concept of theories of the formation of temporary connections of the conditioned reflex; and also consider in more detail the physiology of skin sensitivity.
1.Theories of the formation of a temporary connection of a conditioned reflex A conditioned reflex is a reaction of the body acquired during life as a result of the combination of an indifferent (indifferent) stimulus with an unconditioned one. The physiological basis of the conditioned reflex is the process of closing a temporary connection. A temporary connection is a set of neurophysiological, biochemical and ultrastructural changes in the brain that arise in the process of combining conditioned and unconditioned stimuli and form certain relationships between various brain formations. An irritant is any material agent, external or internal, conscious or unconscious, acting as a condition for subsequent states of the body. A signal stimulus (also indifferent) is a stimulus that has not previously caused a corresponding reaction, but under certain conditions for the formation of a conditioned reflex, begins to cause it. Such a stimulus actually causes an indicative unconditioned reflex. However, with repeated repetition of stimulation, the orienting reflex begins to weaken and then disappears altogether. Stimulus is an influence that determines the dynamics of an individual’s mental states (reaction) and relates to it as cause and effect. Reaction - any response of the body to a change in the external or internal environment, from the biochemical reaction of an individual cell to a conditioned reflex. Stages and mechanism of conditioned reflex The process of formation of a classical conditioned reflex goes through three main stages: The pregeneralization stage is a short-term phase, which is characterized by a pronounced concentration of excitation and the absence of conditioned behavioral reactions. Generalization stage. This is a phenomenon that occurs in the initial stages of developing a conditioned reflex. The required reaction in this case is caused not only by the reinforced stimulus, but also by others, more or less close to it. Specialization stage. During this period, a reaction occurs only to a signal stimulus and the volume of distribution of biopotentials decreases. Initially, I.P. Pavlov assumed that the conditioned reflex is formed at the level of “cortex-subcortical formations”. In later works, he explained the formation of a conditioned reflex connection by the formation of a temporary connection between the cortical center of the unconditioned reflex and the cortical center of the analyzer. In this case, the main cellular elements of the mechanism for the formation of a conditioned reflex are the intercalary and associative neurons of the cerebral cortex, and the closure of the temporary connection is based on the process of dominant interaction between excited centers. Rules for the formation of a conditioned reflex To form a conditioned reflex, the following rules must be observed: An indifferent stimulus must have sufficient strength to excite certain receptors. A receptor is a peripheral specialized part of the analyzer, through which the influence of stimuli from the external world and the internal environment of the body is transformed into the process of nervous excitation. The analyzer is a nervous apparatus that performs the function of analyzing and synthesizing stimuli. It includes the receptor part, the pathways and the analyzer core in the cerebral cortex. However, an excessively strong stimulus may not cause a conditioned reflex. Firstly, its action will cause, according to the law of negative induction, a decrease in cortical excitability, which will lead to a weakening of the BR, especially if the strength of the unconditioned stimulus was small. Secondly, an excessively strong stimulus can cause a focus of inhibition in the cerebral cortex instead of a focus of excitation, in other words, bring the corresponding area of the cortex into a state of extreme inhibition. The indifferent stimulus must be reinforced by an unconditioned stimulus, and it is desirable that it precedes it somewhat or is presented simultaneously with the latter. When exposed first to an unconditional stimulus, and then to an indifferent one, a conditioned reflex, if formed, usually remains very fragile. When both stimuli are turned on simultaneously, it is much more difficult to develop a conditioned reflex. It is necessary that the stimulus used as a conditional stimulus be weaker than the unconditional one. To develop a conditioned reflex, it is also necessary to have normal functioning of cortical and subcortical structures and the absence of significant pathological processes in the body. To develop a conditioned reflex, the absence of strong extraneous stimuli is necessary. Despite certain differences, conditioned reflexes are characterized by the following general properties (features): All conditioned reflexes represent one of the forms of adaptive reactions of the body to changing environmental conditions; Conditioned reflexes belong to the category of reflex reactions acquired during individual life and are distinguished by individual specificity; All types of conditioned reflex activity are of a warning signal nature; Conditioned reflex reactions are formed on the basis of unconditioned reflexes; Without reinforcement, conditioned reflexes are weakened and suppressed over time. Reinforcement is an unconditioned stimulus that causes a biologically significant reaction, provided it is combined with an anticipatory indifferent stimulus, resulting in the development of a classical conditioned reflex. Reinforcement that harms the body is called negative (punishment). Reinforcement in the form of food is called positive (reward). The mechanism of formation of a conditioned reflex Theory of E.A. Asratyan. E.A. Asratyan, studying unconditioned reflexes, came to the conclusion that the central part of the unconditioned reflex arc is not unilinear, it does not pass through one level of the brain, but has a multi-level structure, that is, the central part of the unconditioned reflex arc consists of many branches , which pass through various levels of the central nervous system (spinal cord, medulla oblongata, stem sections, etc.). Moreover, the highest part of the arc passes through the cerebral cortex, through the cortical representation of this unconditioned reflex and personifies the corticolization of the corresponding function. Hasratyan further suggested that if signal and reinforcing stimuli cause their own unconditioned reflexes, then they constitute the neurosubstrate of the conditioned reflex. Indeed, a conditioned stimulus is not absolutely indifferent, since it itself causes a certain unconditioned reflex reaction - an indicative one, and with significant strength this stimulus causes unconditioned visceral and somatic reactions. The arc of the orientation reflex also has a multi-level structure with its own cortical representation. Consequently, when an indifferent stimulus is combined with an unconditioned (reinforcing) one, a temporary connection is formed between the cortical and subcortical branches of two unconditioned reflexes (indicative and reinforcing), that is, the formation of a conditioned reflex is a synthesis of two or more unconditioned reflexes. Theory V.S. Rusinova. In accordance with the teachings of B.S. Rusinov, the conditioned reflex first becomes a dominant, and then a conditioned reflex. If a focus of excitation is created using direct polarization of a portion of the cortex, then a conditioned reflex reaction can be evoked by any indifferent stimulus. The mechanism of conditioned reflex activity Research has shown that there are two mechanisms of conditioned reflex activity: Superstructural, regulating the state of the brain and creating a certain level of excitability and performance of nerve centers; Trigger, who initiates one or another conditioned reaction. The relationship between the left and right hemispheres during the development of a conditioned reflex is carried out through the corpus callosum, camissures, intertubercular fusion, quadrigeminal cord and reticular formation of the brain stem. At the cellular and molecular levels, the temporal connection is closed using memory mechanisms. At the beginning of the development of a conditioned reflex, communication is carried out using short-term memory mechanisms - the spread of excitation between two excited cortical centers. Then it becomes long-term, that is, structural changes occur in neurons. Rice. 1. Diagram of the arc of a conditioned reflex with bilateral communication (according to E.A. Asratyan): a - cortical center of the blink reflex; 6 - cortical center of the food reflex; c, d - subcortical centers of blinking and food reflexes, respectively; I - direct temporary connection; II - time feedback Schemes of reflex arcs: A - two-neuron reflex arc; B - three-neuron reflex arc: 1 - receptor in muscle and tendon; 1a - receptor in the skin; 2 - afferent fiber; 2a - neuron of the spinal ganglion; 3 - intercalary neuron; 4 - motor neuron; 5 - efferent fiber; 6 - effector (muscle). Physiology of skin sensitivity The receptor surface of the skin is 1.5-2 m2. There are quite a few theories about skin sensitivity. The most common one indicates the presence of specific receptors for three main types of skin sensitivity: tactile, temperature and pain. According to this theory, the basis for the different nature of skin sensations is the differences in impulses and afferent fibers excited by different types of skin irritations. Based on the speed of adaptation, skin receptors are divided into fast and slow adapters. The tactile receptors located in the hair follicles, as well as the Golji bodies, adapt most quickly. Adaptation is ensured by the capsule, as it conducts fast and dampens slow changes in pressure. Thanks to this adaptation, we no longer feel the pressure of clothing, etc. There are approximately 500,000 tactile receptors in human skin. The threshold of excitability in different parts of the body is different. Fig.1. Skin receptors. The main sensory apparatus of the skin and mucous membranes usually include: receptors located near the hair follicles that provide the sensation of touch. In relation to them, skin hair plays the role of a lever that perceives tactile stimuli (a kind of functional equivalent of such devices are vibrissae - tactile hairs located on the belly and face of some animals); Meissner's corpuscles, which react to deformation of the skin surface in areas devoid of hair, and free nerve endings that perform a similar function; Merkel discs and Ruffini corpuscles are deeper receptors that respond to pressure. Polymodal mechanoreceptors also include Krause flasks, which are presumably related to the reflection of temperature changes; Paccini corpuscles in the lower part of the skin, responding to vibration stimulation, as well as to some extent to pressure and touch; temperature receptors, which transmit the sensation of cold, and superficially located receptors, when irritated, thermal sensations arise. Both sensations are subjectively dependent on the initial skin temperature, free nerve endings associated with pain (nociceptors). They are also credited with mediating temperature and tactile stimulation. muscle spindles - receptors located in muscles and irritated during active or passive stretching and contraction of muscles; Golgi organ - receptors located in the tendons perceive varying degrees of their tension and react at the moment the movement begins; joint receptors that respond to changes in the position of the joints relative to each other. There is an assumption that the “subject” of their assessment is the angle between the bones that form the articulation. According to modern concepts, fibers branch in the epidermis (upper layer of skin) that perceive pain stimuli and are transmitted to the central nervous system as quickly as possible. Beneath them are touch receptors (tactile), deeper - pain plexuses associated with blood vessels, and even deeper - pressure. Receptors for heat (in the upper and middle layers of the skin itself) and cold (in the epidermis) lie at different levels. In general, human skin and its musculoskeletal system represent a huge complex receptor - a peripheral section of the skin-kinesthetic analyzer. The receptor surface of the skin is huge (1.4-2.1 m2). Afferent stimulation of the skin-kinesthetic analyzer is carried out along fibers that differ in the degree of myelination and, therefore, in the speed of impulse conduction. Fibers that conduct mainly deep pain and temperature sensitivity (very little tactile), after entering the spinal cord, pass to the opposite side of the lateral and anterior columns, slightly above the entry point. Their crossing occurs over a large area of the spinal cord, after which they rise to the thalamus opticus, from where the next neuron begins, directing its processes to the cerebral cortex. Rice. 2. Block diagram of the pathways of tactile sensitivity Theories of skin sensitivity are numerous and largely contradictory. One of the most common is the idea of the presence of specific receptors for 4 main types of skin sensitivity: tactile, thermal, cold and pain. According to this theory, the different nature of skin sensations is based on differences in the spatial and temporal distribution of impulses in afferent fibers excited by different types of skin stimulation. The results of studies of the electrical activity of single nerve endings and fibers indicate that many of them perceive only mechanical or temperature stimuli. Mechanisms of excitation of skin receptors. A mechanical stimulus leads to deformation of the receptor membrane. As a result, the electrical resistance of the membrane decreases and its permeability to Na+ increases. An ionic current begins to flow through the receptor membrane, leading to the generation of a receptor potential. When the receptor potential increases to a critical level of depolarization, impulses are generated in the receptor, propagating along the fiber to the central nervous system. Receptive field. The set of points in the periphery from which peripheral stimuli influence a given sensory cell in the central nervous system is called the receptive field. In one receptive field there are receptors that send nerve impulses to other central neurons, i.e. individual receptive fields overlap. Overlapping receptive fields increases the resolution of reception and recognition of stimulus localization. The relationship between stimulus intensity and response. There is a quantitative relationship between stimulus intensity and response in the form of the frequency of action potentials occurring. The same dependence describes the sensitivity of the sensory neuron in the central nervous system. The only difference is that the receptor responds to the amplitude of the stimulus, and the central sensory neuron responds to the frequency of action potentials coming to it from the receptor. For central sensory neurons, it is not so much the absolute threshold S0 of the stimulus that is important, but the differential one, i.e. difference threshold. The differential threshold is understood as the minimum change in a given stimulus parameter (spatial, temporal, and others) that causes a measurable change in the firing rate of a sensory neuron. It usually depends most strongly on the strength of the stimulus. In other words, the higher the stimulus intensity, the higher the differential threshold, i.e. the worse the differences between stimuli are recognized. For example, for pressure on the skin in a limited range of certain intensities, the differential threshold is equal to a pressure increase of 3%. This means that two stimuli, the intensities of which differ in absolute value by 3% or more, will be recognized. If their intensities differ by less than 3%, then the stimuli will be perceived as identical. Therefore, if after a load of 100 g we put a load of 110 g on our hand, then we will be able to feel this difference. But if you first put 500 g, and then 510 g, then in this case the difference of 10 grams will not be recognized, since it is less than 3% (i.e. less than 15 g) of the value of the original load. Adaptation of sensation. Adaptation of sensation is understood as a decrease in subjective sensitivity to a stimulus against the background of its continuous action. Based on the speed of adaptation during prolonged exposure to a stimulus, most skin receptors are divided into rapidly and slowly adapting. The tactile receptors located in the hair follicles, as well as the lamellar bodies, adapt most quickly. Adaptation of skin mechanoreceptors leads to the fact that we stop feeling the constant pressure of clothing or get used to wearing contact lenses on the cornea of the eyes. Properties of tactile perception. The sensation of touch and pressure on the skin is quite accurately localized, that is, a person relates to a specific area of the skin surface. This localization is developed and consolidated in ontogenesis with the participation of vision and proprioception. Absolute tactile sensitivity varies significantly in different parts of the skin: from 50 mg to 10 g. Spatial discrimination on the skin surface, i.e., a person’s ability to separately perceive touch on two adjacent points of the skin, also differs greatly in different parts of the skin. On the mucous membrane of the tongue, the threshold of spatial difference is 0.5 mm, and on the skin of the back - more than 60 mm. These differences are mainly due to the different sizes of cutaneous receptive fields (from 0.5 mm2 to 3 cm2) and the degree of their overlap. Temperature reception. The human body temperature fluctuates within relatively narrow limits, so information about the ambient temperature, necessary for the functioning of thermoregulation mechanisms, is especially important. Thermoreceptors are located in the skin, cornea, mucous membranes, and also in the central nervous system (hypothalamus). They are divided into two types: cold and thermal (there are much fewer of them and they lie deeper in the skin than cold ones). The most thermoreceptors are in the skin of the face and neck. The histological type of thermoreceptors is not fully understood; it is believed that they may be unmyelinated endings of the dendrites of afferent neurons. Thermoreceptors can be divided into specific and nonspecific. The former are excited only by temperature influences, the latter also respond to mechanical stimulation. The receptive fields of most thermoreceptors are local. Thermoreceptors respond to temperature changes by increasing the frequency of generated impulses, which last steadily throughout the duration of the stimulus. The increase in the frequency of impulses is proportional to the change in temperature, and constant impulses for thermal receptors are observed in the temperature range from 20 to 50 °C, and for cold ones - from 10 to 41 °C. The differential sensitivity of thermoreceptors is high: it is enough to change the temperature by 0.2 °C to cause long-term changes in their impulses. Under some conditions, cold receptors can also be stimulated by heat (above 45 °C). This explains the acute sensation of cold when quickly immersed in a hot bath. An important factor that determines the steady-state activity of thermoreceptors, the central structures associated with them, and human sensations is the absolute value of temperature. At the same time, the initial intensity of temperature sensations depends on the difference in skin temperature and the temperature of the active stimulus, its area and place of application. So, if the hand was held in water at a temperature of 27 °C, then at the first moment when the hand is transferred to water heated to 25 °C, it seems cold, but after a few seconds a true assessment of the absolute temperature of the water becomes possible.
Rice. 4. Block diagram of temperature sensitivity pathways conditioned reflex skin sensitivity Peripheral nervous mechanisms of sensation, including pain, are based on complex interactions of various nervous structures. The nociceptive (pain) impulse arising in the receptors of the skin zones is carried out along the axons of the first neuron (peripheral neuron), located in the cells of the intervertebral nodes. The axons of the first neuron in the dorsal root region enter the spinal cord and end in the dorsal horn cells. One important fact should be noted that on the neurons of the dorsal horns of the spinal cord, as well as on the thalamic nuclei (Durinyan R.A., 1964), afferent fibers of skin sensitivity and pain afferent fibers coming from internal organs are converted. It is important, however, that both somatic and autonomic afferent fibers do not end chaotically, but have a clear somatotopic organization. These data make it possible to understand the origin of referred pain and areas of increased skin sensitivity according to Guesde in the pathology of internal organs. The second neuron, the central one, is located in the posterior horn area. Its axons, crossing in the anterior commissure, move to the periphery of the lateral column and, as part of the spinothalamic fascicle, reach the optic thalamus. In the region of the lateral and central nuclei of the visual thalamus, where the fibers of the second neuron end, there is a third neuron (also central), connecting to the nuclear zone of the cerebral cortex in the region of the posterior central and parietal gyri. Some of the fibers of the second neuron end in the cells of the reticular formation of the brain stem, from where the fibers of the third neuron go to the visual thalamus. In the process of phylo- and ontogenetic development, the skin from the protective covering of the body became a perfect sensory organ (Petrovsky B.V. and Efuni S.N., 1967; Gorev V.P., 1967; Esakov A.I. and Dmitrieva T.M. , 1971, etc.). The skin analyzer is a particularly convenient model for studying the irradiation, concentration and induction of nervous processes (Pshonik A.T., 1939, etc.). Since ancient times, threshold reactions have been important in understanding the mechanisms of brain activity, making it possible to study the state of the receptor apparatus and central structures. Conclusion The physiology of higher nervous activity studies the vital processes of the human body, which are based on reflex activity, which allows the body to adapt to changing environmental conditions, adapt to them and, thereby, survive - i.e. maintain your life and health, which means not only physical, but mental and social well-being. The physiology of higher nervous activity is the basic academic science for the development of such practical disciplines as psychology, pedagogy, medicine, occupational hygiene, sports, training, nutrition, etc. The physiology of higher nervous activity and the properties of nervous processes determines and explains age-related and individual differences in human behavior in constantly changing environmental conditions. Literature 1.Anatomy and physiology of children and adolescents (with age-related characteristics) / Ed. Sapina M. R. - M., 2011 2.Kazin E. M. Fundamentals of individual human health: a textbook for universities - M.: Vlados, 2012 .Medvedev V.I. Psychophysiological problems of activity optimization - M.: Publishing Center "Academy", 2009 .Smirnov V. M. Neurophysiology and higher nervous activity of children and adolescents - M., 2011 .Human physiology / Ed. V. M. Pokrovsky - M., 2008
Ministry of Education and Science of the Russian Federation
Federal State Autonomous Educational Institution of Higher Professional Education
"Russian State Vocational Pedagogical University"
Faculty of Psychology and Pedagogy
Department of PPR
Test
“PHYSIOLOGY OF HIGHER NERVOUS ACTIVITY AND SENSORY SYSTEMS”
Completed by: student gr.
Simanova A.S.
Option: No. 6
Ekaterinburg
Introduction
1. Theories of the formation of a temporary connection of a conditioned reflex
2.Physiology of skin sensitivity
Conclusion
Bibliography
Introduction
Modern pedagogy is based on knowledge of the laws of ontogenesis, not only on the general conditions thanks to which a child becomes a normal person, but also in special developmental circumstances that arise in individual cases, called individual development. These conditions include a complex of natural properties of the body: structure and functioning, the level of mental development and its coordination through education, hygienic standards necessary for the development and functioning of the body.
Physiology is a science that studies the patterns of formation and features of the functioning of an organism in the process of ontogenesis: from the moment of its inception to the completion of the life cycle. As an independent branch of physiological science, age-related physiology was formed relatively recently - in the second half of the 20th century, and almost from the moment of its inception, two directions emerged in it, each of which has its own subject of study, including such a direction as the physiology of the central nervous system. systems.
The purpose of the test is to reveal the concept of theories of the formation of temporary connections of the conditioned reflex; and also consider in more detail the physiology of skin sensitivity.
1.Theories of the formation of a temporary connection of a conditioned reflex
A conditioned reflex is a reaction of the body acquired during life as a result of the combination of an indifferent (indifferent) stimulus with an unconditioned one. The physiological basis of the conditioned reflex is the process of closing a temporary connection. A temporary connection is a set of neurophysiological, biochemical and ultrastructural changes in the brain that arise in the process of combining conditioned and unconditioned stimuli and form certain relationships between various brain formations.
An irritant is any material agent, external or internal, conscious or unconscious, acting as a condition for subsequent states of the body. A signal stimulus (also indifferent) is a stimulus that has not previously caused a corresponding reaction, but under certain conditions for the formation of a conditioned reflex, begins to cause it. Such a stimulus actually causes an indicative unconditioned reflex. However, with repeated repetition of stimulation, the orienting reflex begins to weaken and then disappears altogether.
Stimulus is an influence that determines the dynamics of an individual’s mental states (reaction) and relates to it as cause and effect.
Reaction - any response of the body to a change in the external or internal environment, from the biochemical reaction of an individual cell to a conditioned reflex.
Stages and mechanism of conditioned reflex
The process of formation of a classical conditioned reflex goes through three main stages:
The pregeneralization stage is a short-term phase, which is characterized by a pronounced concentration of excitation and the absence of conditioned behavioral reactions.
Generalization stage. This is a phenomenon that occurs in the initial stages of developing a conditioned reflex. The required reaction in this case is caused not only by the reinforced stimulus, but also by others, more or less close to it.
Specialization stage. During this period, a reaction occurs only to a signal stimulus and the volume of distribution of biopotentials decreases. Initially, I.P. Pavlov assumed that the conditioned reflex is formed at the level of “cortex-subcortical formations”. In later works, he explained the formation of a conditioned reflex connection by the formation of a temporary connection between the cortical center of the unconditioned reflex and the cortical center of the analyzer. In this case, the main cellular elements of the mechanism for the formation of a conditioned reflex are the intercalary and associative neurons of the cerebral cortex, and the closure of the temporary connection is based on the process of dominant interaction between excited centers.
Rules for the formation of a conditioned reflex
To form a conditioned reflex, the following rules must be observed:
An indifferent stimulus must have sufficient strength to excite certain receptors. A receptor is a peripheral specialized part of the analyzer, through which the influence of stimuli from the external world and the internal environment of the body is transformed into the process of nervous excitation. The analyzer is a nervous apparatus that performs the function of analyzing and synthesizing stimuli. It includes the receptor part, the pathways and the analyzer core in the cerebral cortex.
However, an excessively strong stimulus may not cause a conditioned reflex. Firstly, its action will cause, according to the law of negative induction, a decrease in cortical excitability, which will lead to a weakening of the BR, especially if the strength of the unconditioned stimulus was small. Secondly, an excessively strong stimulus can cause a focus of inhibition in the cerebral cortex instead of a focus of excitation, in other words, bring the corresponding area of the cortex into a state of extreme inhibition.
The indifferent stimulus must be reinforced by an unconditioned stimulus, and it is desirable that it precedes it somewhat or is presented simultaneously with the latter. When exposed first to an unconditional stimulus, and then to an indifferent one, a conditioned reflex, if formed, usually remains very fragile. When both stimuli are turned on simultaneously, it is much more difficult to develop a conditioned reflex.
It is necessary that the stimulus used as a conditional stimulus be weaker than the unconditional one.
To develop a conditioned reflex, it is also necessary to have normal functioning of cortical and subcortical structures and the absence of significant pathological processes in the body.
To develop a conditioned reflex, the absence of strong extraneous stimuli is necessary.
Despite certain differences, conditioned reflexes are characterized by the following general properties (features):
All conditioned reflexes represent one of the forms of adaptive reactions of the body to changing environmental conditions;
Conditioned reflexes belong to the category of reflex reactions acquired during individual life and are distinguished by individual specificity;
All types of conditioned reflex activity are of a warning signal nature;
Conditioned reflex reactions are formed on the basis of unconditioned reflexes; Without reinforcement, conditioned reflexes are weakened and suppressed over time.
Reinforcement is an unconditioned stimulus that causes a biologically significant reaction, provided it is combined with an anticipatory indifferent stimulus, resulting in the development of a classical conditioned reflex. Reinforcement that harms the body is called negative (punishment). Reinforcement in the form of food is called positive (reward).
The mechanism of formation of a conditioned reflex
Theory of E.A. Asratyan. E.A. Asratyan, studying unconditioned reflexes, came to the conclusion that the central part of the unconditioned reflex arc is not unilinear, it does not pass through one level of the brain, but has a multi-level structure, that is, the central part of the unconditioned reflex arc consists of many branches , which pass through various levels of the central nervous system (spinal cord, medulla oblongata, stem sections, etc.). Moreover, the highest part of the arc passes through the cerebral cortex, through the cortical representation of this unconditioned reflex and personifies the corticolization of the corresponding function. Hasratyan further suggested that if signal and reinforcing stimuli cause their own unconditioned reflexes, then they constitute the neurosubstrate of the conditioned reflex. Indeed, a conditioned stimulus is not absolutely indifferent, since it itself causes a certain unconditioned reflex reaction - an indicative one, and with significant strength this stimulus causes unconditioned visceral and somatic reactions. The arc of the orientation reflex also has a multi-level structure with its own cortical representation.
Consequently, when an indifferent stimulus is combined with an unconditioned (reinforcing) one, a temporary connection is formed between the cortical and subcortical branches of two unconditioned reflexes (indicative and reinforcing), that is, the formation of a conditioned reflex is a synthesis of two or more unconditioned reflexes.
Theory V.S. Rusinova. In accordance with the teachings of B.S. Rusinov, the conditioned reflex first becomes a dominant, and then a conditioned reflex. If a focus of excitation is created using direct polarization of a portion of the cortex, then a conditioned reflex reaction can be evoked by any indifferent stimulus.
The mechanism of conditioned reflex activity
Research has shown that there are two mechanisms of conditioned reflex activity:
Superstructural, regulating the state of the brain and creating a certain level of excitability and performance of nerve centers;
Trigger, who initiates one or another conditioned reaction.
The relationship between the left and right hemispheres during the development of a conditioned reflex is carried out through the corpus callosum, camissures, intertubercular fusion, quadrigeminal cord and reticular formation of the brain stem. At the cellular and molecular levels, the temporal connection is closed using memory mechanisms. At the beginning of the development of a conditioned reflex, communication is carried out using short-term memory mechanisms - the spread of excitation between two excited cortical centers. Then it becomes long-term, that is, structural changes occur in neurons.
Rice. 1. Diagram of the arc of a conditioned reflex with bilateral communication (according to E.A. Asratyan): a - cortical center of the blink reflex; 6 - cortical center of the food reflex; c, d - subcortical centers of blinking and food reflexes, respectively; I - direct temporary connection; II - time feedback
Schemes of reflex arcs: A - two-neuron reflex arc; B - three-neuron reflex arc: 1 - receptor in muscle and tendon; 1a - receptor in the skin; 2 - afferent fiber; 2a - neuron of the spinal ganglion; 3 - intercalary neuron; 4 - motor neuron; 5 - efferent fiber; 6 - effector (muscle).
Physiology of skin sensitivity
The receptor surface of the skin is 1.5-2 m2. There are quite a few theories about skin sensitivity. The most common one indicates the presence of specific receptors for three main types of skin sensitivity: tactile, temperature and pain. According to this theory, the basis for the different nature of skin sensations is the differences in impulses and afferent fibers excited by different types of skin irritations. Based on the speed of adaptation, skin receptors are divided into fast and slow adapters. The tactile receptors located in the hair follicles, as well as the Golji bodies, adapt most quickly. Adaptation is ensured by the capsule, as it conducts fast and dampens slow changes in pressure. Thanks to this adaptation, we no longer feel the pressure of clothing, etc.
There are approximately 500,000 tactile receptors in human skin. The threshold of excitability in different parts of the body is different.
Fig.1. Skin receptors.
The main sensory apparatus of the skin and mucous membranes usually include:
receptors located near the hair follicles that provide the sensation of touch. In relation to them, skin hair plays the role of a lever that perceives tactile stimuli (a kind of functional equivalent of such devices are vibrissae - tactile hairs located on the belly and face of some animals);
Meissner's corpuscles, which react to deformation of the skin surface in areas devoid of hair, and free nerve endings that perform a similar function;
Merkel discs and Ruffini corpuscles are deeper receptors that respond to pressure. Polymodal mechanoreceptors also include Krause flasks, which are presumably related to the reflection of temperature changes;
Paccini corpuscles in the lower part of the skin, responding to vibration stimulation, as well as to some extent to pressure and touch;
temperature receptors, which transmit the sensation of cold, and superficially located receptors, when irritated, thermal sensations arise. Both sensations are subjectively dependent on the initial skin temperature,
free nerve endings associated with pain (nociceptors). They are also credited with mediating temperature and tactile stimulation.
Posture and movement receptors include:
muscle spindles - receptors located in muscles and irritated during active or passive stretching and contraction of muscles;
Golgi organ - receptors located in the tendons perceive varying degrees of their tension and react at the moment the movement begins;
joint receptors that respond to changes in the position of the joints relative to each other. There is an assumption that the “subject” of their assessment is the angle between the bones that form the articulation.
According to modern concepts, fibers branch in the epidermis (upper layer of skin) that perceive pain stimuli and are transmitted to the central nervous system as quickly as possible. Beneath them are touch receptors (tactile), deeper - pain plexuses associated with blood vessels, and even deeper - pressure. Receptors for heat (in the upper and middle layers of the skin itself) and cold (in the epidermis) lie at different levels. In general, human skin and its musculoskeletal system represent a huge complex receptor - a peripheral section of the skin-kinesthetic analyzer. The receptor surface of the skin is huge (1.4-2.1 m2).
Afferent stimulation of the skin-kinesthetic analyzer is carried out along fibers that differ in the degree of myelination and, therefore, in the speed of impulse conduction.
Fibers that conduct mainly deep pain and temperature sensitivity (very little tactile), after entering the spinal cord, pass to the opposite side of the lateral and anterior columns, slightly above the entry point. Their crossing occurs over a large area of the spinal cord, after which they rise to the thalamus opticus, from where the next neuron begins, directing its processes to the cerebral cortex.
Rice. 2. Block diagram of the pathways of tactile sensitivity
Theories of skin sensitivity are numerous and largely contradictory. One of the most common is the idea of the presence of specific receptors for 4 main types of skin sensitivity: tactile, thermal, cold and pain. According to this theory, the different nature of skin sensations is based on differences in the spatial and temporal distribution of impulses in afferent fibers excited by different types of skin stimulation. The results of studies of the electrical activity of single nerve endings and fibers indicate that many of them perceive only mechanical or temperature stimuli.
Mechanisms of excitation of skin receptors. A mechanical stimulus leads to deformation of the receptor membrane. As a result, the electrical resistance of the membrane decreases and its permeability to Na+ increases. An ionic current begins to flow through the receptor membrane, leading to the generation of a receptor potential. When the receptor potential increases to a critical level of depolarization, impulses are generated in the receptor, propagating along the fiber to the central nervous system.
Receptive field. The set of points in the periphery from which peripheral stimuli influence a given sensory cell in the central nervous system is called the receptive field.
In one receptive field there are receptors that send nerve impulses to other central neurons, i.e. individual receptive fields overlap. Overlapping receptive fields increases the resolution of reception and recognition of stimulus localization.
The relationship between stimulus intensity and response. There is a quantitative relationship between stimulus intensity and response in the form of the frequency of action potentials occurring. The same dependence describes the sensitivity of the sensory neuron in the central nervous system. The only difference is that the receptor responds to the amplitude of the stimulus, and the central sensory neuron responds to the frequency of action potentials coming to it from the receptor.
For central sensory neurons, it is not so much the absolute threshold S0 of the stimulus that is important, but the differential one, i.e. difference threshold. The differential threshold is understood as the minimum change in a given stimulus parameter (spatial, temporal, and others) that causes a measurable change in the firing rate of a sensory neuron. It usually depends most strongly on the strength of the stimulus. In other words, the higher the stimulus intensity, the higher the differential threshold, i.e. the worse the differences between stimuli are recognized.
For example, for pressure on the skin in a limited range of certain intensities, the differential threshold is equal to a pressure increase of 3%. This means that two stimuli, the intensities of which differ in absolute value by 3% or more, will be recognized. If their intensities differ by less than 3%, then the stimuli will be perceived as identical. Therefore, if after a load of 100 g we put a load of 110 g on our hand, then we will be able to feel this difference. But if you first put 500 g, and then 510 g, then in this case the difference of 10 grams will not be recognized, since it is less than 3% (i.e. less than 15 g) of the value of the original load.
Adaptation of sensation. Adaptation of sensation is understood as a decrease in subjective sensitivity to a stimulus against the background of its continuous action. Based on the speed of adaptation during prolonged exposure to a stimulus, most skin receptors are divided into rapidly and slowly adapting. The tactile receptors located in the hair follicles, as well as the lamellar bodies, adapt most quickly. Adaptation of skin mechanoreceptors leads to the fact that we stop feeling the constant pressure of clothing or get used to wearing contact lenses on the cornea of the eyes.
Properties of tactile perception. The sensation of touch and pressure on the skin is quite accurately localized, that is, a person relates to a specific area of the skin surface. This localization is developed and consolidated in ontogenesis with the participation of vision and proprioception. Absolute tactile sensitivity varies significantly in different parts of the skin: from 50 mg to 10 g. Spatial discrimination on the skin surface, i.e., a person’s ability to separately perceive touch on two adjacent points of the skin, also differs greatly in different parts of the skin. On the mucous membrane of the tongue, the threshold of spatial difference is 0.5 mm, and on the skin of the back - more than 60 mm. These differences are mainly due to the different sizes of cutaneous receptive fields (from 0.5 mm2 to 3 cm2) and the degree of their overlap.
Temperature reception. The human body temperature fluctuates within relatively narrow limits, so information about the ambient temperature, necessary for the functioning of thermoregulation mechanisms, is especially important. Thermoreceptors are located in the skin, cornea, mucous membranes, and also in the central nervous system (hypothalamus). They are divided into two types: cold and thermal (there are much fewer of them and they lie deeper in the skin than cold ones). The most thermoreceptors are in the skin of the face and neck. The histological type of thermoreceptors is not fully understood; it is believed that they may be unmyelinated endings of the dendrites of afferent neurons.
Thermoreceptors can be divided into specific and nonspecific. The former are excited only by temperature influences, the latter also respond to mechanical stimulation. The receptive fields of most thermoreceptors are local. Thermoreceptors respond to temperature changes by increasing the frequency of generated impulses, which last steadily throughout the duration of the stimulus. The increase in the frequency of impulses is proportional to the change in temperature, and constant impulses for thermal receptors are observed in the temperature range from 20 to 50 °C, and for cold ones - from 10 to 41 °C. The differential sensitivity of thermoreceptors is high: it is enough to change the temperature by 0.2 °C to cause long-term changes in their impulses.
Under some conditions, cold receptors can also be stimulated by heat (above 45 °C). This explains the acute sensation of cold when quickly immersed in a hot bath. An important factor that determines the steady-state activity of thermoreceptors, the central structures associated with them, and human sensations is the absolute value of temperature. At the same time, the initial intensity of temperature sensations depends on the difference in skin temperature and the temperature of the active stimulus, its area and place of application. So, if the hand was held in water at a temperature of 27 °C, then at the first moment when the hand is transferred to water heated to 25 °C, it seems cold, but after a few seconds a true assessment of the absolute temperature of the water becomes possible.
Rice. 4. Block diagram of temperature sensitivity pathways
conditioned reflex skin sensitivity
Peripheral nervous mechanisms of sensation, including pain, are based on complex interactions of various nervous structures. The nociceptive (pain) impulse arising in the receptors of the skin zones is carried out along the axons of the first neuron (peripheral neuron), located in the cells of the intervertebral nodes. The axons of the first neuron in the dorsal root region enter the spinal cord and end in the dorsal horn cells. One important fact should be noted that on the neurons of the dorsal horns of the spinal cord, as well as on the thalamic nuclei (Durinyan R.A., 1964), afferent fibers of skin sensitivity and pain afferent fibers coming from internal organs are converted. It is important, however, that both somatic and autonomic afferent fibers do not end chaotically, but have a clear somatotopic organization. These data make it possible to understand the origin of referred pain and areas of increased skin sensitivity according to Guesde in the pathology of internal organs. The second neuron, the central one, is located in the posterior horn area. Its axons, crossing in the anterior commissure, move to the periphery of the lateral column and, as part of the spinothalamic fascicle, reach the optic thalamus. In the region of the lateral and central nuclei of the visual thalamus, where the fibers of the second neuron end, there is a third neuron (also central), connecting to the nuclear zone of the cerebral cortex in the region of the posterior central and parietal gyri. Some of the fibers of the second neuron end in the cells of the reticular formation of the brain stem, from where the fibers of the third neuron go to the visual thalamus.
In the process of phylo- and ontogenetic development, the skin from the protective covering of the body became a perfect sensory organ (Petrovsky B.V. and Efuni S.N., 1967; Gorev V.P., 1967; Esakov A.I. and Dmitrieva T.M. , 1971, etc.). The skin analyzer is a particularly convenient model for studying the irradiation, concentration and induction of nervous processes (Pshonik A.T., 1939, etc.). Since ancient times, threshold reactions have been important in understanding the mechanisms of brain activity, making it possible to study the state of the receptor apparatus and central structures.
Conclusion
The physiology of higher nervous activity studies the vital processes of the human body, which are based on reflex activity, which allows the body to adapt to changing environmental conditions, adapt to them and, thereby, survive - i.e. maintain your life and health, which means not only physical, but mental and social well-being.
The physiology of higher nervous activity is the basic academic science for the development of such practical disciplines as psychology, pedagogy, medicine, occupational hygiene, sports, training, nutrition, etc. The physiology of higher nervous activity and the properties of nervous processes determines and explains age-related and individual differences in human behavior in constantly changing environmental conditions.
Literature
1.Anatomy and physiology of children and adolescents (with age-related characteristics) / Ed. Sapina M. R. - M., 2011
2.Kazin E. M. Fundamentals of individual human health: a textbook for universities - M.: Vlados, 2012
.Medvedev V.I. Psychophysiological problems of activity optimization - M.: Publishing Center "Academy", 2009
.Smirnov V. M. Neurophysiology and higher nervous activity of children and adolescents - M., 2011
.Human physiology / Ed. V. M. Pokrovsky - M., 2008
Tutorial
Moscow, 2007
Introduction……………………………………………………
1.1. Receptors........................................................
1.2. Basic principles of encoding and transmission of sensory information ……………………………
1.2.1. Coding of signal characteristics at the receptor level……………………………………
1.2.2. Basic principles of sensory signal transmission to the central nervous system………………………..
1.3. Perception of sensory information……….
2. Visual sensory system...................................
2.1. Organ of vision........................................................
2.1.1. The membranes of the eye.............................................
2.1.2. Inner nucleus of the eye......................
2.1.3. Anatomy and physiology of the retina.....
2.2. Conducting department of the visual sensory system.................................................... ......................
2.3. Cortical visual sensory system
2.4. Eye movements……………………………………
3. Auditory sensory system....................................
3.1. Hearing organ……………………………………………………………
3.1.1. Outer and middle ear…………………
3.1.2. Inner ear…………………………. 3.2. Conducting section of the auditory sensory system…………………
3.3. Cortical part of the auditory sensory system.
4. Vestibular sensory system.................................
5. Somatic sensitivity………………………..
5. 1. Cutaneous sensory system.................................
5.2. Muscular sensory system........................
6. Sensory systems with chemical sensitivity receptors (chemoreceptors)
6.1. Olfactory sensory system......................
6.2. Taste sensory system.........................
6.3. Internal reception (visceroreception) .......
Bibliography …………………………………………..
Introduction
Physiology is the science of the life activity (functions) of the whole organism and its individual parts - cells, tissues, organs, functional systems. When studying life processes, physiology uses data from many other sciences - anatomy, cytology, histology, biochemistry. Physiology is an experimental science that uses many techniques to study the functioning of the body. Modern physiology actively uses physical and chemical research methods.
The course “Physiology of Higher Nervous Activity and Sensory Systems” can be divided into two relatively independent sections – “Physiology of Higher Nervous Activity (HNA)” and “Physiology of Sensory Systems”. The physiology of higher nervous activity studies the mechanisms of higher nervous activity - activity aimed at adapting to constantly changing environmental conditions. The physiology of sensory systems (analyzers) studies the ways in which the nervous system perceives and analyzes stimuli acting on the body from both its external and internal environment. Both sections are the most important components of the entire complex of neurosciences.
This manual examines the general principles and patterns of the structure of sensory systems and their operation, as well as the structure and operation of each sensory system separately.
1. General principles of organization of sensory systems
Sensor system (analyzer)- a complex complex of nervous formations that perceive and analyze stimuli from the external and internal environment of the body. The concept of “analyzer” was introduced by I.P. Pavlov, who considered each of them as a single multi-level system, including peripheral and central sections. Pavlov identified three sections in each analyzer: peripheral (receptor), conductive (sensory nerves and ganglia, as well as nuclei and pathways in the central nervous system) and cortical (the area of the cerebral cortex where information about the stimulus comes most quickly). It has now been found that at each level of the analyzer, incoming information is analyzed and processed.
To understand further material, let us briefly recall the main types of electrical potentials in cells. You can read more about them in any textbook on the physiology of the central nervous system or in a manual on the physiology of the central nervous system published by MELI (see list of references).
The potential difference between the external and internal environment of the cell is usually called the membrane potential (MP). In almost all cells of the body, the inner surface of the cytoplasmic membrane is negatively charged compared to its outer surface, i.e. MP is negative. In most cells of the body, MP is constant; it does not change its value throughout life.
However, in the cells of excitable tissues (nervous, muscle, glandular) MP changes under various influences on the cell. Therefore, in the absence of influences, it is called the resting potential (RP). It is customary to say about the cytoplasmic membrane (or about the entire cell) in this state that it is polarized. Electrical phenomena in cells are associated with the presence of ion channels - protein molecules embedded in the cytoplasmic membrane. Under certain influences, channels in such molecules can open, which allow various ions to pass through, which leads to a shift in the PP.
During synaptic transmission on the postsynaptic membrane, depending on the type of synapse, postsynaptic potentials (PSPs) are generated (formed) - excitatory (EPSP) or inhibitory (IPSP). The EPSP represents a small decrease in absolute value (depolarization) and the IPSP a small increase (hyperpolarization) of the resting potential. The magnitude of postsynaptic potentials depends on the amount of transmitter released into the synaptic cleft from the presynaptic terminal. Such potentials are local, i.e., arising on the postsynaptic membrane, they do not spread across the neuron membrane.
The basic unit of information transmission in the nervous system is the nerve impulse or action potential (AP). In order for a cell to form an AP, a certain level of depolarization (threshold level) is required. This level is reached as a result of the summation of EPSPs. PD arises according to the “all or nothing” law, i.e. at a subthreshold level of depolarization, the AP is not generated (nothing), after reaching the threshold level, whatever the magnitude of the depolarization, the amplitude of the AP is the same (everything). After the occurrence of the AP, it spreads along the membrane, reaching the presynaptic terminal, where it causes the release of the transmitter into the synaptic cleft and the appearance of PSP on the postsynaptic membrane.
The most peripheral section of the analyzer is receptor transfers the energy of the stimulus into a nervous process. Receptors of sensory systems should be distinguished from synaptic, hormonal and other molecular receptors (i.e. membrane receptors). In sensory systems, a receptor is a sensitive cell or a sensitive process of a cell. Under the influence of a stimulus, the properties of ion channels built into the receptor membrane change. This, as a rule, leads to the entry of positively charged ions into the receptor and depolarization of the membrane - an upward shift in the membrane potential. Arises receptor potential, in many respects similar to EPSP (excitatory postsynaptic potential). Just like EPSP, the receptor potential is local, i.e. does not spread across the membrane from its point of origin, and is gradual, i.e. varies in size depending on the strength of the stimulus. Just like the EPSP, the receptor potential is capable of triggering an action potential.
In addition to receptors, the peripheral nervous system contains sensory ganglia (spinal and cranial) and nerves that conduct sensory information to the central nervous system (Fig. 1).
The central nervous system contains pathways and nuclei (sensory centers), as well as the highest section of the analyzer - a section of the cerebral cortex, where information from the corresponding receptors is projected. In the nuclei, not only the switching of nerve impulses going to the cerebral cortex occurs, but also the processing of sensory information.
IN cortical section analyzer (in the corresponding projection zone of the cortex), sensory information is formalized into sensation. When the cerebral cortex is destroyed, the resulting irritation is not perceived by consciousness, although it can be processed and used by the underlying areas of the central nervous system (at an unconscious level).
Around some receptors there is a complex of auxiliary formations, which, on the one hand, protect the receptors from external inadequate influences, and on the other hand, provide optimal conditions for their functioning. In combination with receptors, these formations are called sense organs. Traditionally, humans have five senses: vision, hearing, touch, smell and taste. However, the number of stimuli we perceive is noticeably greater.
The fact is that the term “sense organ” arose in psychology in accordance with the sensations realized by a person. However, in the process of development of physiology, it became clear that there are a number of stimuli that are not perceived (or not always perceived) by humans as sensations, but are absolutely necessary for the normal functioning of the body.
In this regard, it is necessary to introduce the concept of “modality”, usually used in physiology in relation to stimuli and receptors. Modality– this is a qualitative characteristic of the stimulus, as well as the sensation that occurs when a certain sensory system is activated. Such modalities are visual, auditory, gustatory, olfactory and a number of modalities whose receptors are located in the skin. The term modality can also be applied to stimuli that cause mostly unconscious changes in the body. Such stimuli are visceral (from internal organs), proprioceptive (from muscle, tendon and joint receptors), and vestibular.
Receptors
Due to the large number of perceived signals and sensations, the receptors present in the human body are very diverse. In addition, for a number of modalities there is more than one type of receptor. There are several classifications of receptors, the most commonly used of which are given below.
All receptors are divided into two large groups - exteroceptors And interoreceptors. The first includes receptors that perceive stimuli from the external environment (auditory, visual, tactile, olfactory, taste), the second - from the internal. Interoreceptors, in turn, are divided into proprioceptors or proprioceptors (receptors of muscles, tendons and joints), transmitting information about the state of the musculoskeletal system, vestibuloreceptors, informing about the position of the body in space, and visceroceptors located in internal organs (for example, pressure receptors in blood vessels).
Based on the type of perceived energy (which is then converted into the energy of nerve impulses), mechanoreceptors, chemoreceptors, photoreceptors, and thermoreceptors are distinguished. Mechanoreceptors include some of the skin receptors that perceive touch, pressure and vibration, auditory and vestibular receptors, proprioceptors, and stretch receptors in the walls of internal organs. Chemoreceptors are olfactory and taste receptors, as well as a number of visceroceptors located in the vessels, gastrointestinal tract, central nervous system, etc. A special type of chemoreceptors are nociceptors, specific pain receptors. Photoreceptors are the rods and cones of the retina. Thermoreceptors combine receptors of the skin and internal organs, as well as special thermoneurons located in the central nervous system.
Finally, receptors are divided according to the method of transmitting information to the central nervous system into primary sensers(primary) and secondary sensers(secondary). Primary receptors are part of nerve (sensory) cells. In this case, part of the cell (dendrite) forms the actual receptor, which perceives the stimulus and generates a receptor potential. The latter is capable of triggering an action potential, which is carried out in the central nervous system by the same sensory neuron. Such receptors are cutaneous and olfactory.
Most of the remaining receptors are secondary. In this case, a special receptor cell generates a receptor potential, but cannot convert it into an action potential and transmit it to the central nervous system, since it is not a neuron and does not have processes. However, it forms a synapse with the dendrite of the sensitive (sensory) nerve cell. When a receptor potential occurs, the receptor cell releases a mediator that excites the sensory neuron, which causes an action potential in it, which is then transmitted to the central nervous system (Fig. 2).
One of the basic functions of living systems is the ability to adapt. Adaptation– the process of adaptation of the body to changing environmental conditions. It can manifest itself at different levels of the organization. For example, a change in behavior is an adaptation at the level of the whole organism, an increase in oxidative processes during intense muscular work is an adaptation at the level of the respiratory system, etc.
Many receptors are also capable of adaptation. Most often it manifests itself in the form of addiction to the stimulus, i.e. to a decrease in receptor sensitivity. In this case, the receptors actively respond only to the beginning of stimulation, but after a short time they stop responding to it or respond much weaker. Such receptors ( phasic or quickly adaptable) generate a potential again either when the stimulus ceases or when its parameters change. For example, Pacinian corpuscles (tactile receptors) can completely stop generating potentials 1 second after the onset of constant pressure, but respond immediately after the stimulus is removed. Thanks to adaptation, new stimuli are masked to a much lesser extent by constantly acting signals, which facilitates the functioning of attention systems. However, a number of receptors ( tonic or slow to adapt) continues to respond throughout the duration of the stimulus (Fig. 3). Such receptors are, for example, chemoreceptors and auditory receptors. In this case, adaptation is also possible, but it is already a function of the central nervous system.
TEST QUESTIONS FOR THE EXAM
PHYSIOLOGY OF VNI AND SENSORY SYSTEMS
History of the development of views on higher nervous activity. Subject and tasks of the physiology of higher nervous activity. Methods for studying behavior and the brain.
Fundamentals of the theory of reflex activity.
General signs and types of conditioned reflexes. Conditions for the development of conditioned reflexes. Conditioned reflexes to simple and complex stimuli. Conditioned reflexes of higher orders.
Functional basis of temporary connection closure. Dominant and conditioned reflex.
Inhibition of conditioned reflexes.
Unconditioned reflexes and their classification. Instincts. Orienting reflex.
Movement of nervous processes along the cerebral cortex. Dynamic stereotype.
Features of human higher nervous activity. The role of the hemispheres in the functions of the first and second signaling systems.
Development of speech in ontogenesis.
Types of higher nervous activity of animals and humans according to I.P. Pavlova.
Typological personality variants of adults and children.
The role of genotype and environment in the formation of GNI type and character.
The concept of functional states and their indicators.
Functional role of sleep. Mechanisms of sleep. Dreams, hypnosis.
Stress. Definition, stages of development.
Features of GNI in early and adolescent children.
Features of the GNI of a mature and elderly person.
Functional blocks of the brain.
The concept of a functional system.
Functional system of behavioral act.
Methods for obtaining experimental neuroses. Relationship between neurotic disorders and psychological characteristics.
Disorders of human higher nervous activity.
Concept of the sensory system. Structural and functional organization of analyzers. Properties of analyzers.
Visual analyzer.
Hearing analyzer.
Vestibular, motor analyzers.
Skin and internal analyzers.
Taste and olfactory analyzers.
Pain analyzer.
Forms of learning.
1. History of the development of views on higher nervous activity. Subject and tasks of the physiology of higher nervous activity. Methods for studying behavior and the brain.
The successes of the natural sciences have long created the prerequisites for revealing the nature of mental phenomena. However, in science for a long time religious and mystical ideas about the disembodied “soul” commanding the body dominated. Therefore, the great French scientist Rene Descartes (1596–1650), having proclaimed the principle of reflex (Descartes' arc) - reflected action as a method of brain activity, stopped halfway, not daring to extend it to the manifestation of the mental sphere. Such a bold step was taken 200 years later by the “father of Russian physiology” Ivan Mikhailovich Sechenov (1829–1905).
In 1863 I.M. Sechenov published a work entitled “Reflexes of the Brain.” In it, he provided convincing evidence of the reflex nature of mental activity, pointing out that not a single impression, not a single thought arises on its own, that the reason is the action of some cause - a physiological stimulus. He wrote that a wide variety of experiences, feelings, thoughts ultimately lead, as a rule, to some kind of response.
According to I.M. Sechenov, brain reflexes include three parts. The first, initial, link is excitation in the senses caused by external influences. The second, central link is the processes of excitation and inhibition occurring in the brain. On their basis, mental phenomena arise (sensations, ideas, feelings, etc.). The third, final link is human movements and actions, i.e. his behavior. All these links are interconnected and conditioned.
“Brain reflexes” were far ahead of the development of science during Sechenov’s time. Therefore, in some respects, his teaching remained a brilliant hypothesis and was not completed.
The successor of the ideas of I.M. Sechenov became another genius of Russian science - Ivan Petrovich Pavlov (1849–1936). He developed a scientific method with which he was able to penetrate the secrets of the brain of animals and humans. He created the doctrine of unconditioned and conditioned reflexes. Research by I.P. Pavlov in the field of blood circulation and digestion paved the way for the transition to the physiological study of the most complex function of the body - mental activity.
The subject of GND physiology is an objective study of the material substrate of the mental activity of the brain and the use of this knowledge to solve practical problems of maintaining human health and high performance, and managing behavior.
Methods of VND PHYSIOLOGY.
The objective study of conditioned reflexes made it possible to develop additional methods for studying and localizing the processes of higher nervous activity. Of these, the following methods are most commonly used.
The ability to form conditioned reflexes to different forms of stimuli.
Ontogenetic study of conditioned reflexes.By studying the complex behavior of animals of different ages, it is possible to establish what in this behavior is acquired and what is innate.Phylogenetic study of conditioned reflexes.By comparing conditioned reflexes in animals at different levels of development, it is possible to establish in what directions the evolution of higher nervous activity is taking place.
Ecological study of conditioned reflexes.Studying the living conditions of an animal can be a good technique for revealing the origin of the characteristics of its higher nervous activity.
Use of electrical indicators of conditioned reflex reactivity.The activity of nerve cells in the brain is accompanied by the emergence of electrical potentials in them, from which, to a certain extent, one can judge the distribution paths and properties of nervous processes - links of conditioned reflex acts.
Direct irritation of the nerve structures of the brain. This method allows you to interfere with the natural order of the conditioned reflex and study the work of its individual links.
Pharmacological effects on conditioned reflexes.Different substances have different effects on the activity of nerve cells. This allows us to study the dependence of conditioned reflexes on changes in their activity.
Creation of an experimental pathology of conditioned reflex activity. Controlled physical destruction of individual parts of the brain makes it possible to study their role in the formation and maintenance of conditioned reflexes.
Conditional process modeling- reflex activity. The results of mathematical analysis provide grounds for judging the patterns of formation of conditioned connections and allow, in a model experiment, to predict the possibility of the formation of a conditioned reflex with a particular order of combinations of conditioned and unconditioned stimuli.
Comparison of mental and physiological manifestations of VED processes. Such comparisons are used in the study of higher functions of the human brain. Appropriate techniques were used to study the neurophysiological processes underlying the phenomena of attention, learning, memory, etc.
2. Fundamentals of the theory of reflex activity.
The main structural and functional unit of the nervous system is the nerve cell with all its processes - the neuron, and the main mechanism of activity of the nervous system is the reflex. A reflex is the reaction of nerve centers in response to irritation of receptors. I. P. Pavlov defines a reflex as “a nervous connection between agents of the external environment perceived by animal (and human) receptors with certain activities of the body.” This definition affirms, firstly, the position about the unity of the organism and the external environment, and secondly, the position about the reflective function of the reflex - that “the first reason for every action of animals and humans lies outside it” (I.M. Sechenov) .
The concept of reflex activity covers lower and higher nervous activity. The anatomical substrate of lower nervous activity is: the midbrain, hindbrain (cerebellum, pons), medulla oblongata and spinal cord. It is mainly in charge of the relationship and integration of parts of the body with each other. These forms of reflex activity are partially covered in the previous chapters, where we discussed the autonomic reflex regulation of the digestive organs, cardiac and vascular activity, urination, metabolic processes, etc. In subsequent chapters, the description of lower nervous activity will be supplemented by somatic reflexes, thanks to which perception of stimuli from the external world and the implementation of movements in animals and humans.
The anatomical substrate of higher nervous activity is the cerebral cortex of the hungry brain and the subcortex closest to it (striatum, visual hillocks, subtubercular region). Higher nervous activity consists of: 1) innate complex forms of behavior called instincts or complex unconditioned reflexes; 2) individual higher nervous activity acquired in the life of each individual - conditioned reflexes.
The most complex unconditioned reflexes serve complex forms of body activity: finding food (food instinct), eliminating harmful things (defensive instinct), procreation (sexual and parental instincts) and other complex forms of innate nervous activity. These complex reflexes are caused by certain, very limited in number of stimuli, ensure the existence of a person only in early childhood, with parental care, and are not sufficient to determine the independent existence of animals and humans. Acquired reflex reactions - conditioned reflexes - arise “after birth, in the individual lives of animals and humans, depending on the external environment, and constitute a fund of individual reflex reactions that is constantly changing under the influence of experience. Conditioned reflexes adapt the instinctive activity of the body to the constantly changing conditions of the external environment and provide an ever-expanding and limitless opportunity for a person to adapt to the outside world and navigate in it. The concept of conditioned reflexes also includes forms of higher nervous activity that are specifically inherent in humans. According to I.P. Pavlov, they constitute specifically human, higher thinking, which creates first universal human empiricism, and finally science - a tool for man’s highest orientation in the world around him and in himself. According to I.P. Pavlov, the human brain, which created and is creating natural science, thus itself becomes the object of this natural science. These provisions were brilliantly foreseen by I.M. Sechenov in his work, which played a significant role: “Reflexes of the Brain” (1863). Sechenov put forward the thesis that all forms of human nervous activity and his thinking are reflexes: “Does a child laugh at the sight of a toy, does Garibaldi smile when he is persecuted for excessive love for his homeland, does a girl tremble at the first thought of love, does she create Newton wrote the laws of the world and wrote them on paper - everywhere the final act is muscular movement.” Substantiating his positions with the facts of contemporary physiology, in particular the laws of nervous activity discovered by him (central inhibition, summation), I.M. Sechenov argued that human thought is a reflex, but only a reflex with a truncated, inhibited end.
The experimental substantiation of the brilliant foresight of I.M. Sechenov was given by I.P. Pavlov in his doctrine of conditioned reflexes, and in. in particular in the provisions on the second, specifically human signaling system. The second signaling system, which in comparison with animals constitutes an addition to the first signaling system common to animals and humans, is human speech, human verbal activity. It introduced a new principle into the work of the cerebral hemispheres - it made it possible to abstract from immediate reality through a broad generalization of the first signals of reality, which we experience as sensations and ideas about specific objects and phenomena of the external world. The success of a person’s cognitive activity and his thinking is consolidated in speech and thereby provides the opportunity for a wide exchange of experience.
3. General signs and types of conditioned reflexes. Conditions for the development of conditioned reflexes. Conditioned reflexes to simple and complex stimuli. Conditioned reflexes of higher orders.
One of the main elementary acts of higher nervous activity is the conditioned reflex. The biological significance of conditioned reflexes lies in a sharp expansion in the number of signal stimuli that are significant for the body, which ensures an incomparably higher level of adaptive behavior.
The conditioned reflex mechanism underlies the formation of any acquired skill, the basis of the learning process. The structural and functional basis of the conditioned reflex is the cortex and subcortical formations of the brain.
The essence of the conditioned reflex activity of the body comes down to the transformation of an indifferent stimulus into a signal, meaningful one, due to the repeated reinforcement of the irritation with an unconditioned stimulus. Due to the reinforcement of a conditioned stimulus by an unconditioned stimulus, a previously indifferent stimulus is associated in the life of the organism with a biologically important event and thereby signals the occurrence of this event. In this case, any innervated organ can act as an effector link in the reflex arc of a conditioned reflex. There is no organ in the human or animal body whose functioning could not change under the influence of a conditioned reflex. Any function of the body as a whole or of its individual physiological systems can be modified (strengthened or suppressed) as a result of the formation of a corresponding conditioned reflex.
The physiological mechanism underlying the conditioned reflex is schematically presented in. In the zone of the cortical representation of the conditioned stimulus and the cortical (or subcortical) representation of the unconditioned stimulus, two foci of excitation are formed. The focus of excitation caused by an unconditional stimulus of the external or internal environment of the body, as a stronger (dominant) one, attracts to itself excitation from the focus of weaker excitation caused by the conditioned stimulus. After several repeated presentations of the conditioned and unconditioned stimuli, a stable path of excitation movement is “trodden” between these two zones: from the focus caused by the conditioned stimulus to the focus caused by the unconditioned stimulus. As a result, the isolated presentation of only the conditioned stimulus now leads to the response caused by the previously unconditioned stimulus.
The main cellular elements of the central mechanism for the formation of a conditioned reflex are intercalary and associative neurons of the cerebral cortex.
For the formation of a conditioned reflex, the following rules must be observed: 1) an indifferent stimulus (which must become a conditioned, signal) must have sufficient strength to excite certain receptors; 2) it is necessary that the indifferent stimulus be reinforced by an unconditioned stimulus, and the indifferent stimulus must either slightly precede or be presented simultaneously with the unconditioned one; 3) it is necessary that the stimulus used as a conditional stimulus be weaker than the unconditional one. To develop a conditioned reflex, it is also necessary to have a normal physiological state of the cortical and subcortical structures that form the central representation of the corresponding conditioned and unconditioned stimuli, the absence of strong extraneous stimuli, and the absence of significant pathological processes in the body.
If the specified conditions are met, a conditioned reflex can be developed to almost any stimulus.
I. P. Pavlov, the author of the doctrine of conditioned reflexes as the basis of higher nervous activity, initially assumed that the conditioned reflex is formed at the level of the cortex - subcortical formations (a temporary connection is made between the cortical neurons in the zone of representation of the indifferent conditioned stimulus and the subcortical nerve cells that make up the central representation unconditional stimulus). In later works, I. P. Pavlov explained the formation of a conditioned reflex connection by the formation of a connection at the level of the cortical zones of the representation of conditioned and unconditioned stimuli.
Subsequent neurophysiological studies led to the development, experimental and theoretical substantiation of several different hypotheses about the formation of a conditioned reflex (Fig. 15.2). Data from modern neurophysiology indicate the possibility of different levels of closure, the formation of a conditioned reflex connection (cortex - cortex, cortex - subcortical formations, subcortical formations - subcortical formations) with a dominant role in this process of cortical structures. Obviously, the physiological mechanism for the formation of a conditioned reflex is a complex dynamic organization of cortical and subcortical structures of the brain (L. G. Voronin, E. A. Asratyan, P. K. Anokhin, A. B. Kogan).
Despite certain individual differences, conditioned reflexes are characterized by the following general properties (features):
1. All conditioned reflexes represent one of the forms of adaptive reactions of the body to changing environmental conditions.
2. Conditioned reflexes belong to the category of reflex reactions acquired during individual life and are distinguished by individual specificity.
3. All types of conditioned reflex activity are of a warning signal nature.
4. Conditioned reflex reactions are formed on the basis of unconditioned reflexes; Without reinforcement, conditioned reflexes are weakened and suppressed over time.
4. Functional basis of temporary connection closure. Dominant and conditioned reflex.
I.P. Pavlov believed that the closure of temporary connections occurs in the cerebral cortex between the point that perceives the conditioned stimulus and the cortical representation of the unconditioned reflex. Each conditioned signal enters the cortical end of the analyzer, into the projection zone corresponding to the stimulus modality. Each unconditioned stimulus, the center of which is located in the subcortical structures, has its own representation in the cerebral cortex.
E.A. Asratyan, studying the unconditioned reflexes of normal and decorticated animals, came to the conclusion that the central part of the arc of the unconditioned reflex is not unilinear, does not pass through any one level of the brain, but has a multi-level structure, i.e. the central part of the arc of the unconditioned reflex consists of many branches that pass through various levels of the central nervous system, spinal cord, medulla oblongata, stem sections, etc. (Fig. 18). The highest part of the arc passes through the cerebral cortex, is the cortical representation of this unconditioned reflex and personifies the corticolization of the corresponding function. Further E.A. Asratyan suggested that if signal and reinforcing stimuli cause their own unconditioned reflexes, then they constitute the neurosubstrate of the conditioned reflex. Indeed, a conditioned stimulus is not absolutely indifferent, since it itself causes a certain unconditioned reflex reaction - an indicative one, and with significant strength this “indifferent” stimulus causes unconditioned defensive, visceral and somatic reactions. The arc of the indicative (unconditioned) reflex also has a multi-level structure with its own cortical representation in the form of a cortical “branch” of the reflex arc (see Fig. 18). Speaking about reinforcement, about unconditioned stimuli, it should be borne in mind that it is not they as such that participate in the closure mechanism, but the unconditioned reflexes caused by these factors and the corresponding neurophysiological and neurochemical processes at all levels of the central nervous system. Consequently, when an indifferent (light) stimulus is combined with an unconditioned reflex (food), reinforcing reflex, a temporary connection is formed between the cortical (and subcortical) branches of two unconditioned reflexes (indicative and reinforcing), i.e. the formation of a conditioned reflex is synthesis two (or several) differentunconditioned reflexes(E.A. Asratyan).
During the formation of a conditioned reflex, a functional restructuring occurs in the cortical projections of signal and reinforcing stimuli. Gradually, the signal stimulus begins to evoke a previously unusual conditioned reaction, while at the same time its “own” unconditional reflex reaction changes. It turned out to be logical that as the signal stimulus is combined with reinforcement, on the one hand, there is a decrease in the threshold (sensitization) of the conditioned response, and on the other hand, the threshold of the “own” unconditional reaction increases, i.e. the reaction caused by the conditioned stimulus before learning .
The manifestations of the “own” unconditional reaction and the developed conditioned reaction often demonstrate a reciprocal relationship with each other: when the “own” reaction is well expressed, the conditioned reaction does not manifest itself and vice versa.
Thus, the “own” effector expression of the conditioned stimulus fades away during the learning process (as a result of internal inhibition), while at the same time, in the efferent part of the arc of the reinforcing stimulus, excitability increases and the conditioned stimulus becomes effective for triggering an effector reaction that was previously unusual for it.
5. Inhibition of conditioned reflexes.
The functioning of the conditioned reflex mechanism is based on two main nervous processes: excitation and inhibition. At the same time, as the conditioned reflex becomes established and strengthened, the role of the inhibitory process increases.
Depending on the nature of the physiological mechanism underlying the inhibitory effect on the conditioned reflex activity of the body, unconditioned (external and beyond) and conditioned (internal) inhibition of conditioned reflexes are distinguished.
External inhibition of a conditioned reflex occurs under the influence of another extraneous conditioned or unconditioned stimulus. However, the main reason for the suppression of the conditioned reflex is not. depends on the inhibited reflex itself and does not require special development. External inhibition occurs when the corresponding signal is first presented.
Transcendental inhibition of the conditioned reflex develops either when the strength of the stimulus is excessively high, or when the functional state of the central nervous system is low, at the level of which ordinary threshold stimuli acquire the character of excessive, strong ones. Extreme inhibition has a protective value.
The biological meaning of unconditional external inhibition of conditioned reflexes comes down to ensuring a reaction to the main, most important for the body at a given moment in time, stimulus while simultaneously inhibiting, suppressing the reaction to a secondary stimulus, which in this case is a conditioned stimulus.
Conditioned (internal) inhibition of a conditioned reflex is conditional in nature and requires special development. Since the development of the inhibitory effect is associated with the neurophysiological mechanism of formation of the conditioned reflex, such inhibition belongs to the category of internal inhibition, and the manifestation of this type of inhibition is associated with certain conditions (for example, repeated application of a conditioned stimulus without reinforcement), such inhibition is also conditional.
The biological meaning of internal inhibition of conditioned reflexes is that changed environmental conditions (cessation of reinforcement of a conditioned stimulus by an unconditioned one) require a corresponding adaptive change in conditioned reflex behavior. The conditioned reflex is suppressed, suppressed, because it ceases to be a signal foreshadowing the appearance of an unconditioned stimulus.
There are four types of internal inhibition: extinction, differentiation, conditioned inhibition, delay.
If a conditioned stimulus is presented without reinforcement by an unconditioned one, then some time after the isolated application of the conditioned stimulus, the reaction to it fades away. This inhibition of the conditioned reflex is called extinction (extinction). The extinction of a conditioned reflex is a temporary inhibition, suppression of a reflex reaction. It does not mean the destruction or disappearance of this reflex reaction. After some time, a new presentation of a conditioned stimulus without reinforcement by an unconditioned one initially again leads to the manifestation of a conditioned reflex reaction.
If in an animal or person with a developed conditioned reflex to a certain frequency of a sound stimulus (for example, the sound of a metronome with a frequency of 50 per second), stimuli that are similar in meaning (the sound of a metronome with a frequency of 45 or 55 per second) are not reinforced with an unconditioned stimulus, then a conditioned reflex reaction to the latter it is inhibited, suppressed (an initially conditioned reaction is also observed to these frequencies of sound stimulation). This type of internal (conditioned) inhibition is called differential inhibition (differentiation). Differential inhibition underlies many forms of learning associated with the development of fine skills.
If a conditioned stimulus to which a conditioned reflex is formed is used in combination with some other stimulus and their combination is not reinforced by an unconditioned stimulus, inhibition of the conditioned reflex caused by this stimulus occurs. This type of conditioned inhibition is called conditioned inhibition.
Delayed inhibition occurs when the reinforcement of a conditioned signal with an unconditioned stimulus is carried out with a large delay (2-3 minutes) in relation to the moment of presentation of the conditioned stimulus.
6. Unconditioned reflexes and their classification. Instincts. Orienting reflex.
The question of the classification of unconditioned reflexes still remains open, although the main types of these reactions are well known. Let us dwell on some particularly important unconditioned human reflexes.
1. Food reflexes. For example, salivation when food enters the oral cavity or the sucking reflex in a newborn baby.
2. Defensive reflexes. Reflexes that protect the body from various adverse effects, an example of which may be the reflex of withdrawing the hand when a finger is painfully irritated.
3. Orienting reflexes. Any new unexpected stimulus attracts the person’s attention.
4. Gaming reflexes. This type of unconditioned reflexes is widely found in various representatives of the animal kingdom and also has adaptive significance. Example: puppies playing. They hunt each other, sneak up and attack their “enemy”. Consequently, during the game the animal creates models of possible life situations and carries out a kind of “preparation” for various life surprises.
While maintaining its biological foundations, children's play acquires new qualitative features - it becomes an active tool for learning about the world and, like any other human activity, acquires a social character. Play is the very first preparation for future work and creative activity.
The child's play activity appears from 3-5 months of postnatal development and underlies the development of his ideas about the structure of the body and the subsequent isolation of himself from the surrounding reality. At 7-8 months, play activities acquire an “imitative or educational” character and contribute to the development of speech, improvement of the child’s emotional sphere and enrichment of his ideas about the surrounding reality. From the age of one and a half years, the child’s play becomes more and more complicated; the mother and other people close to the child are introduced into play situations, and thus the foundations are created for the formation of interpersonal, social relationships.
In conclusion, it should also be noted that sexual and parental unconditioned reflexes associated with the birth and feeding of offspring, reflexes that ensure movement and balance of the body in space, and reflexes that maintain homeostasis of the body.
Instincts. A more complex, unconditional reflex activity is instincts, the biological nature of which remains unclear in its details. In a simplified form, instincts can be represented as a complex interconnected series of simple innate reflexes.
7. Movement of nervous processes along the cerebral cortex. Dynamic stereotype.
Nervous processes- excitation and inhibition - never remain motionless, are not limited to the point of the central nervous system in which they arose. Having started in a certain place, they spread from there to other parts of the nervous system. This phenomenon, as already noted, is called irradiation.
The process opposite to irradiation is the concentration of nervous processes, or their concentration (after the initial irradiation) in a more limited place.
Both nervous processes radiate and concentrate: both excitation and inhibition.
The irradiation of excitation along the cerebral cortex plays an important role in the formation of a conditioned reflex, which, as already mentioned, is always associated with the spread of excitation from one part of the brain to another. The fact of primary generalization of the conditioned reflex also shows that the nervous process initially involves a significant number of cells in the cerebral cortex. Only later is the reaction to unreinforced stimuli inhibited, and the process of excitation is concentrated, concentrated in a relatively small group of cells associated with reinforcement by an unconditioned stimulus.
The process of irradiation of inhibition and its subsequent concentration was demonstrated in the laboratories of I. P. Pavlov in the following experiments.
Several devices were attached to the dog's skin - kasalok, located in a row from the neck to the hip. The irritation of the skin by the graze was reinforced by food, so that soon the action of each graze began to cause a conditioned reflex - the release of saliva. Then the action of one (lowest) tangent was stopped being reinforced with food, as a result of which its action ceased to cause a salivary reflex; Inhibition developed at a point in the cortex corresponding to this area of the skin. If, 1 minute after using this lower tangent, which had now become a “brake”, the skin was irritated by a neighboring tangent, which had previously caused a significant salivary reaction, then it turned out that skin irritation with this tangent now almost did not cause saliva secretion, while skin irritation a far-distant tangent still gave a normal salivary reaction. After 3 minutes, the braking extended to the next, further located tangent. This means that the process of inhibition radiated through the cerebral cortex, gradually spreading to more and more distant areas.
In a similar way, one can trace the concentration of inhibition. If you continue the experiment and try the action of the second and third tangents after longer periods of time after the action of the “braking” tangent, then you can see how first the action of the far-distant tangent is released from inhibition, and then those that are closer to the “brake” tangent. This means that the process, which initially spread to increasingly distant points of the cortex, gradually concentrates in the original inhibitory point.
Irradiation and concentration- the main forms of movement of nervous processes along the cerebral cortex. Thanks to the irradiation of nervous processes, a large number of cells of the cerebral cortex are involved in a vital reaction, and this makes it possible to form connections between the most different parts of the cerebral cortex. Thanks to the concentration of nervous processes, which occurs much more slowly than irradiation and represents considerable labor for the nervous system, it becomes possible to develop subtle and perfect forms of adaptation of the animal to changing environmental conditions.
The irradiation and concentration of excitation and inhibition depend on a number of conditions and, above all, on the strength, stimuli and the nervous processes they cause. With weak and very strong excitation and inhibition, significant irradiation of these processes is observed; with average strength, the concentration of excitation or inhibition at the point of application of stimulation.
Irradiation and concentration depend further on the general condition of the cerebral cortex. In a weakened or tired cortex, the irradiation of nervous processes becomes especially wide and diffuse; This explains, for example, the disordered flow of thoughts in a half-asleep or tired state.
Irradiation and concentration also depend on the balance of the processes of excitation and inhibition. If excitation processes predominate over inhibition processes, their concentration becomes especially difficult.
It is characteristic that the ability to concentrate nervous processes changes with age. In a small child, in whom the processes of active internal inhibition are still weak, the concentration of nervous processes during the formation of temporary connections is still very difficult, and the processes in the cerebral cortex are of a very irradiated nature. As development progresses, the movement of nervous processes becomes more and more perfect, and both of its forms - irradiation and concentration of nervous processes - are balanced.
The law of mutual induction of nervous processes is important in the activity of the nervous system, according to which each of the nervous processes - excitation and inhibition - causes or enhances the opposite process. Excitation arising in a certain area of the cerebral cortex causes an inhibition process (negative induction) in the areas located around it. The inhibition that occurs at a certain point causes the opposite process of excitation (positive induction) in the surrounding areas.
Similar phenomena of mutual induction can be observed in the same point of the cerebral cortex (if we trace the reaction of this point in successive periods of time). If a certain signal, which caused a conditioned reaction of significant strength, is presented again after a very short period of time after it was already presented, its action will be temporarily inhibited. This happens because the previous excitation caused after itself - by virtue of the law of induction - the process of inhibition. On the contrary, the inhibitory state of a certain part of the cortex, due to sequential induction, can cause a further increase in its active state. This type of induction is called sequential induction (or induction in time) in contrast to the simultaneous induction (or induction in space) described above.
These inductive relationships between excitation and inhibition underlie the concentration of neural processes. Thanks to them, an extremely subtle and clear distinction between excited and inhibitory points is possible, characterizing the active state of the cerebral cortex.
8. Features of human higher nervous activity. The role of the hemispheres in the functions of the first and second signaling systems.
The higher nervous activity of humans differs significantly from the higher nervous activity of animals. In a person, in the process of his social and labor activity, a fundamentally new signaling system arises and reaches a high level of development.
Higher nervous activity (HNA) is the activity of the main parts of the central nervous system, ensuring the adaptation of animals and humans to the environment. The basis of higher nervous activity is reflexes (unconditioned and conditioned). The emergence of new conditioned reflexes during the life of an organism, allowing it to respond expediently to external stimuli and thereby adapt to constantly changing environmental conditions. Attenuation or disappearance of previously developed reflexes due to inhibition when the environment changes.
The principles and patterns of higher nervous activity are common to both animals and humans. However, the higher nervous activity of humans differs significantly from the higher nervous activity of animals. In a person, in the process of his social and labor activity, a fundamentally new signaling system arises and reaches a high level of development.
The first signal system of reality is the system of our immediate sensations, perceptions, impressions of specific objects and phenomena of the surrounding world. The word (speech) is the second signaling system (signal of signals). It arose and developed on the basis of the first signaling system and is significant only in close connection with it.
Thanks to the second signaling system (the word), humans form temporary connections more quickly than animals, because the word carries the socially developed meaning of the object. Temporary human nervous connections are more stable and remain without reinforcement for many years.
Human mental activity is inextricably linked with the second signaling system. Thinking is the highest level of human cognition, the process of reflection in the brain of the surrounding real world, based on two fundamentally different psychophysiological mechanisms: the formation and continuous replenishment of the stock of concepts, ideas and the derivation of new judgments and conclusions.
A feature of the human psyche is the awareness of many processes of his inner life.
Unlike animals, who perceive events according to their biological significance, man perceives the world around him in concepts that have developed in the historical and individual experience of his social existence. This perception has an active character, expressed primarily by selective attention.
9. Development of speech in ontogenesis.
Language development occurs as the brain matures and new and increasingly complex temporal connections are formed. In an infant, the first conditioned reflexes are unstable and appear from the second, sometimes third month of life. Conditioned food reflexes to taste and smell stimuli are formed first, then to vestibular (swaying) and later to sound and visual. An infant is characterized by weakness in the processes of excitation and inhibition. He easily develops protective inhibition. This is indicated by the almost continuous sleep of the newborn (about 20 hours).
Conditioned reflexes to verbal stimuli appear only in the second half of the year of life. When adults communicate with a child, the word is usually combined with other direct stimuli. As a result, it becomes one of the components of the complex. For example, to the words “Where is mom?” the child reacts by turning his head towards the mother only in combination with other stimuli: kinesthetic (from body position), visual (familiar surroundings, the face of the person asking the question), auditory (voice, intonation). It is necessary to change one of the components of the complex, and the reaction to the word disappears. Gradually, the word begins to acquire a leading meaning, displacing other components of the complex. First, the kinesthetic component drops out, then visual and sound stimuli lose their significance. And just one word causes a reaction.
The presentation of a certain object while simultaneously naming it leads to the fact that the word begins to replace the object it denotes. This ability appears in a child towards the end of the first year of life or the beginning of the second. However, the word first replaces only a specifican object, for example a given doll, and not a doll in general. that is, the word appears at this stage of development asfirst order integrator.
Turning a word intosecond order integratoror in "signaling" occurs at the end of the second year of life. To do this, it is necessary that at least 15 different conditional connections (a bundle of connections) be developed for it. The child must learn to operate with various objects denoted by one word. If the number of conditional connections developed is smaller, then the word remains a symbol that only replaces a specific object.
Between 3 and 4 years of life the words appear -third order integrators.The child begins to understand words such as “toy”, “flowers”, “animals”. By the fifth year of life, the child develops more complex concepts. Thus, he applies the word “thing” to toys, dishes, furniture, etc.
The development of the second signaling system occurs in close connection with the first. In the process of ontogenesis, several phases of development of the joint activity of two signaling systems are distinguished.
Initially, the child’s conditioned reflexes are carried out at the level of the first signal system. that is, the direct stimulus comes into contact with immediate vegetative and somatic reactions. According to the terminology of A.G. Ivanov-Smolensky, these are connections of the H-H type (“immediate stimulus - immediate reaction”). In the second half of the year, the child begins to respond to verbal stimuli with immediate vegetative and somatic reactions. Thus, conditional connections of the C-H type (“verbal stimulus - immediate reaction”) are added. By the end of the first year of life (after 8 months), the child begins to imitate the speech of an adult in the same way as primates do, with the help of individual sounds denoting something outside or some own state. Then the child begins to pronounce words. At first they are also not associated with any events in the outside world. At the same time, at the age of 1.5-2 years, one word often denotes not only an object, but also actions and experiences associated with it. Later, differentiation of words denoting objects, actions, and feelings occurs. Thus, a new type of H-C connections is added (“immediate stimulus - verbal reaction”). In the second year of life, the child’s vocabulary increases to 200 or more words. He begins to combine words into simple speech chains, and then build sentences. By the end of the third year, the vocabulary reaches 500-700 words. Verbal reactions are caused not only by direct stimuli, but also by words. The child learns to speak. Thus, a new type of S-C connections arises (“verbal stimulus - verbal reaction”).
With the development of speech and the formation of the generalizing effect of a word, the integrative activity of the brain becomes more complicated in a child aged 2-3 years: conditioned reflexes arise to the relationships between sizes, weight, distance, and color of objects. Children aged 3-4 years develop various motor stereotypes. However, among conditioned reflexes, direct temporary connections predominate. Feedbacks arise later and the power relations between them level out by 5-6 years of life.
10. Types of higher nervous activity of animals and humans according to I.P. Pavlova.
Based on the properties of nervous processes, I.P. Pavlov managed to divide animals into certain groups, and this classification coincided with the speculative classification of types of people (temperaments), given by Hippocrates. The classification of GNI types was based on the properties of nervous processes: strength, balance and mobility. Based on the criterion of the strength of nervous processes, strong and weak types are distinguished. In the weak type, the processes of excitation and inhibition are weak, so the mobility and balance of nervous processes cannot be characterized accurately enough.
The strong type of nervous system is divided into balanced and unbalanced. A group is distinguished that is characterized by unbalanced processes of excitation and inhibition with a predominance of excitation over inhibition (uncontrolled type), when the main property is imbalance. For a balanced type, in which the processes of excitation and inhibition are balanced, the speed of change in the processes of excitation and inhibition becomes important. Depending on this indicator, mobile and inert types of VND are distinguished. Experiments carried out in the laboratories of I.P. Pavlov made it possible to create the following classification of types of VND:
Weak (melancholic).
Strong, unbalanced with a predominance of excitation processes (choleric).
Strong, balanced, agile (sanguine).
Strong, balanced, inert (phlegmatic).
Types of VNI are common to animals and humans. It is possible to identify special typological features inherent only to humans. According to I.P. Pavlov, they are based on the degree of development of the first and second signaling systems.First signaling system- these are visual, auditory and other sensory signals from which images of the external world are built.
The perception of direct signals from objects and phenomena of the surrounding world and signals from the internal environment of the body, coming from visual, auditory, tactile and other receptors, constitutes the first signaling system that animals and humans have. Separate elements of a more complex signaling system begin to appear in social species of animals (highly organized mammals and birds), which use sounds (signal codes) to warn of danger, that a given territory is occupied, etc.
But only a person develops in the process of work activity and social lifesecond signaling system- verbal, in which the word as a conditioned stimulus, a sign that has no real physical content, but is a symbol of objects and phenomena of the material world, becomes a strong stimulus. This signaling system consists of the perception of words - heard, spoken (aloud or silently) and visible (when reading and writing). The same phenomenon, object in different languages is denoted by words that have different sounds and spellings, and abstract concepts are created from these verbal (verbal) signals.
Stimuli of the second signaling system reflect the surrounding reality with the help of generalizing, abstract concepts expressed in words. A person can operate not only with images, but also with thoughts associated with them, meaningful images containing semantic (semantic) information. With the help of a word, a transition is made from the sensory image of the first signaling system to the concept, representation of the second signaling system. The ability to operate with abstract concepts expressed in words, serving as the basis for mental activity.
Taking into account the relationship between the first and second signaling systems in a particular individual, I.P. Pavlov identified specific human types of GNI depending on the predominance of the first or second signaling system in the perception of reality. People with a predominance of the functions of cortical projections responsible for primary signal stimuli were classified by I.P. Pavlov as an artistic type (in representatives of this type the imaginative type of thinking predominates). These are people who are characterized by brightness of visual and auditory perception of events in the surrounding world (artists and musicians).
If the second signaling system turns out to be stronger, then such people are classified as the thinking type. Representatives of this type are dominated by the logical type of thinking, the ability to construct abstract concepts (scientists, philosophers). In cases where the first and second signaling systems create nervous processes of equal strength, then such people belong to the average (mixed type), which is the majority of people. But there is another extremely rare typological variant, which includes very rare people who have particularly strong development of both the first and second signaling systems. These people are capable of both artistic and scientific creativity; I.P. Pavlov included Leonardo da Vinci among such brilliant personalities.
11. Typological personality options for adults and children.
Typological features of the child’s GNI. N.I. Krasnogorsky, studying the child’s GNI on the basis of strength, balance, mobility of nervous processes, relationships between the cortex and subcortical formations, and the relationship between signaling systems, identified 4 types of nervous activity in childhood.
1. Strong, balanced, optimally excitable, fast type. Characterized by the rapid formation of strong conditioned reflexes. Children of this type have well-developed speech with a rich vocabulary.
2. Strong, balanced, slow type. In children of this type, conditional connections are formed more slowly and their strength is less. Children of this type quickly learn to speak, but their speech is somewhat slower. They are active and persistent when performing complex tasks.
Strong, unbalanced, highly excitable, unrestrained type. Conditioned reflexes in such children quickly fade away. Children of this type are characterized by high emotional excitability and hot temper. Their speech is fast with occasional shouts.
4. Weak type with reduced excitability. Conditioned reflexes are formed slowly, unstable, speech is often slow. Children of this type cannot tolerate strong and prolonged irritation and get tired easily.
Significant differences in the basic properties of nervous processes in children belonging to different types determine their different functional capabilities in the process of learning and upbringing, but the plasticity of the cells of the cerebral cortex, their adaptability to changing environmental conditions is the morphofunctional basis for the transformation of the GNI type. Since the plasticity of nervous structures is especially great during the period of their intensive development, pedagogical influences that correct typological features are especially important to apply in childhood.
12. The role of genotype and environment in the formation of GNI type and character.
The relationship between strength, balance and mobility of the basic nervous processes determines the typology of the individual’s higher nervous activity. The systematization of the types of higher nervous activity is based on an assessment of the three main features of the processes of excitation and inhibition: strength, balance and mobility, which are the result of inherited and acquired individual qualities of the nervous system. A type as a set of innate and acquired properties of the nervous system that determine the nature of the interaction between the organism and the environment is manifested in the peculiarities of the functioning of the physiological systems of the body and, above all, the nervous system itself, its higher “floors” that provide higher nervous activity.
Types of higher nervous activity are formed on the basis of both genotype and phenotype. The genotype is formed in the process of evolution under the influence of natural selection, ensuring the development of individuals most adapted to the environment. Under the influence of environmental conditions actually operating throughout an individual’s life, the genotype forms the phenotype of the organism.
The influence of hereditary factors on behavioral characteristics has been well studied in animals. Thus, as a result of selecting and dividing the most active and passive rats according to their motor behavior and selectively crossing them within each group, after several generations, it was possible to develop two pure lines: “active” and “passive” rats, whose behavior differs in the level of motor activity. The basis of this division is the difference between animals according to genotype.
The hereditary nature of the property of mobility of the nervous system was studied by V.K. Fedorov, who also composed separate groups of rats: with high, medium and low mobility. Then the property of mobility was studied in the offspring of each group of animals. It turned out that the offspring of the “mobile” group more often showed this quality (50%) than the offspring of other groups. In these experiments, the indicator of mobility was the alteration of the signal meaning of a pair of stimuli.
To study the hereditary factor in the formation of individual differences, the twin method is important. It is known that identical twins have identical genotype (genetic information). Therefore, in pairs of identical twins, differences in temperament, if they are genetically determined, should be less than among fraternal twins, and even more so among non-relatives. Of course, this is only true if the pairs of twins live in the same conditions. The twin method shows that motor activity, complex movements (traversing a labyrinth, inserting a needle into a hole), especially subtle movements of the hands, are hereditarily determined.
13. The concept of functional states and their indicators.
The relationship between the functional state (FS) and the effectiveness of the work performed is usually described in the form of a dome-shaped curve. This introduces the conceptoptimal functional state,in which a person achieves the highest results. Therefore, FS management is one of the important reserves that can be used to increase the efficiency of human activity in production, at school, at a university and in other areas of social practice. Optimization of physical activity is an indispensable condition for the formation of a healthy lifestyle.
Most often, FS is defined asbackground activity of the central nervous system,the conditions under which this or that activity is carried out.
However, today, despite the obvious practical significance of the PS problem, methods for diagnosing and optimizing PS remain insufficiently studied. To a large extent, this situation is due to the lack of development of the theory of FS and the lack of a clear conceptual apparatus. This also applies to the very concept of FS.
The study of the modulating systems of the brain: the reticular formation with its activating and inactivating sections, as well as the limbic system, on which motivational arousal depends, gives grounds to distinguish them into a special functional system that has several levels of response: physiological, behavioral and psychological (subjective). The expression of the activity of this functional system is the FS.A functional state is a psychophysiological phenomenon with its own patterns, which are embedded in the architecture of a special functional system.This view of PS emphasizes the importance of studying one’s own mechanisms of PS regulation. Only on the basis of knowledge about the real processes of FS management can one create adequate methods for diagnosing FS, as those that best meet its basic laws.
The definition of FS through behavioral reactions leads to the identification of FS with the concept of level of wakefulness. The proposal to separate the concept of “level of wakefulness” from the concept of “level of activity” of nerve centers (functional state) was first expressed by V. Blok.Level of wakefulnesshe considers it as a behavioral manifestation of various levels of functional state.
The idea that the level of activation of nerve centers determines the level of wakefulness formed the basis of G. Moruzzi’s scheme. According to his ideas, various forms of instinctive behavior, including sleep, can be placed on a scale of levels of wakefulness. Each type of instinctive behavior corresponds to a certain level of reticular activation.
The relationship between the level of wakefulness and physical activity was studied experimentally by E.H. Sokolov and N.H. Danilova. In the scheme summarizing the results obtained and the authors’ ideas about the relationship between functional states, levels of wakefulness and instinctive behavior (unconditioned reflexes) with the effectiveness of task execution, the classification of instinctive behavior proposed by J. Moruzzi is supplemented with indicative behavior. Unconditioned reflexes: defensive, food, sexual, orientation, transition to sleep, sleep - are located on a scale of wakefulness levels and each of them corresponds to a certain level of functional state. In this schemethe functional state is isolated as an independent phenomenon.
Recently, thefunctions of modulating systemsand, consequently, the mechanisms of regulation of PS. At the same time, their greater significance for behavior was revealed than previously thought. The view of FS only as a factor that worsens or improves the performance of activities has been replaced by the idea of its more fundamental role in behavior.
14. Functional role of sleep. Mechanisms of sleep. Dreams, hypnosis.
Sleep is a vital, periodically occurring special functional state characterized by specific electrophysiological, somatic and vegetative manifestations.
It is known that the periodic alternation of natural sleep and wakefulness belongs to the so-called circadian rhythms and is largely determined by daily changes in illumination. A person spends about a third of his life sleeping, which has led to a long-standing and keen interest among researchers in this condition.
According to the definition of I. P. Pavlov and many of his followers, natural sleep is a diffuse inhibition of cortical and subcortical structures, cessation of contact with the outside world, extinction of afferent and efferent activity, shutdown of conditioned and unconditioned reflexes during sleep, as well as the development of general and particular relaxation. Modern physiological studies have not confirmed the presence of diffuse inhibition. Thus, microelectrode studies revealed a high degree of neuronal activity during sleep in almost all parts of the cerebral cortex. From the analysis of the pattern of these discharges, it was concluded that the state of natural sleep represents a different organization of brain activity, different from brain activity in the waking state.
The following main stages of sleep are distinguished:
Stage I - drowsiness, the process of falling into sleep. During night sleep, this stage is usually short-lived (1-7 minutes). Sometimes you can observe slow movements of the eyeballs (SMG), while fast movements of the eyeballs (REM) are completely absent;
stage II is characterized by the appearance on the EEG of so-called sleep spindles (12-18 per second) and vertex potentials, biphasic waves with an amplitude of about 200 μV against a general background of electrical activity with an amplitude of 50-75 μV, as well as K-complexes (vertex potential with subsequent “sleepy spindle”). This stage is the longest of all; it can take up about 50% of the entire night's sleep. No eye movements are observed;
Stage III is characterized by the presence of K-complexes and rhythmic activity (5-9 per second) and the appearance of slow or delta waves (0.5-4 per second) with an amplitude above 75 μV. The total duration of delta waves in this stage occupies from 20 to 50% of the entire III stage. There are no eye movements. Quite often this stage of sleep is called delta sleep.
Stage IV - the stage of “rapid” or “paradoxical” sleep is characterized by the presence of desynchronized mixed activity on the EEG: fast low-amplitude rhythms (in these manifestations it resembles stage I and active wakefulness - beta rhythm), which can alternate with low-amplitude slow and short bursts of alpha rhythm, sawtooth discharges, REM with closed eyelids.
Night sleep usually consists of 4-5 cycles, each of which begins with the first stages of “slow” sleep and ends with “rapid” sleep. The duration of the cycle in a healthy adult is relatively stable and amounts to 90-100 minutes. In the first two cycles, “slow” sleep predominates, in the last two cycles, “fast” sleep predominates, and “delta” sleep is sharply reduced and may even be absent.
The physiological significance of dreams lies in the fact that in dreams the mechanism of imaginative thinking is used to solve problems that could not be solved in wakefulness with the help of logical thinking. A striking example is the famous case of D.I. Mendeleev, who “saw” the structure of his famous periodic table of elements in a dream.
Dreams are a mechanism of a kind of psychological defense - reconciliation of unresolved conflicts in wakefulness, relieving tension and anxiety.
Hypnosis comes from the Greek hypnos meaning sleep. However, perhaps this is the only thing that unites these two concepts. Hypnosis in its essence differs sharply from the state of natural sleep.
Hypnosis is a special state of a person, induced artificially, through suggestion, and characterized by selectivity of response, increased susceptibility to the psychological influence of the hypnotizer and decreased susceptibility to other influences.
The following stages of hypnosis are distinguished:
1) the hypnoid stage is accompanied by muscle and mental relaxation, blinking and closing the eyes;
2) the stage of light trance, which is characterized by catalepsy of the limbs, i.e. the limbs can be in an unusual position for a long time;
3) the middle trance stage, during which amnesia and personality changes occur; simple hypnotic suggestions are possible;
4) the stage of deep trance is characterized by complete somnambulism and fantastic suggestions.
15. Stress. Definition, stages of development.
The author of the concept of stress, Hans Selye, distinguishes “stress” from “distress” 1 . His concept of stress is identical to a change in the functional state that corresponds to the task being solved by the body. Even in a state of complete relaxation, a sleeping person experiences some stress. Distress is stress that is unpleasant and harms the body.
Nowadays the word “stress” is more often understood in the narrow sense of the word. i.e. stress - This is the tension that occurs when threatening or unpleasant factors appear in a life situation.It is now customary to talk about stress as a special functional state with which the body reacts to extreme impacts that pose a threat to a person’s physical well-being, existence or mental status. Thus, stress arises as a reaction of the body, covering a complex of changes at the behavioral, vegetative, humoral, biochemical levels, as well as at the mental level, including subjective emotional experiences.
Stress is characterized by dynamics and has a logic of its development.
Biological function of stress- adaptation. It is designed to protect the body from threatening, destructive influences of various kinds: physical, mental. Therefore, the appearance of stress means that a person engages in a certain type of activity aimed at counteracting the dangerous influences to which he is exposed.
Influences that cause stress are called stressors.There are physiological and psychological stressors.Physiological stressorshave a direct effect on body tissue. These include painful effects, cold, high temperature, excessive physical activity, etc.Psychological stressors- these are stimuli that signal the biological or social significance of events. These are signals of threat, danger, anxiety, resentment, and the need to solve a difficult problem.
According to two types of stressors, they distinguishphysiological stress and psychological.The latter is divided into informational and emotional.
According to G. Selye,Stage I of stress (anxiety)consists of mobilizing the body’s adaptive capabilities, in which resistance to stress falls below normal. It is expressed in the reactions of the adrenal glands, the immune system and the gastrointestinal tract, already described as the “stress triad”. If the stressor is severe (severe burns, extreme heat or cold), death may occur due to limited reserves.
Stage II of stress- stage of resistance.If the action is compatible with the possibilities of adaptation, then the resistance phase in the body stabilizes. At the same time, signs of anxiety practically disappear, and the level of resistance rises significantly above normal. Stage III - exhaustion phase. As a result of prolonged exposure to a stress stimulus, despite increased resistance to stress, adaptive energy reserves are gradually depleted. Then the signs of an anxiety reaction reappear, but now they are irreversible and the individual dies.
Extreme situations that cause stress are divided into short-term and long-term. With short-term stress, ready-made response programs are updated, and with long-term stress, adaptive restructuring of functional systems is required, sometimes extremely severe and unfavorable for human health.
16. Features of GNI in early and adolescent children.
The lower and higher nervous activity of the child is formed as a result of the morphofunctional maturation of the entire nervous system. The nervous system, and with it the higher nervous activity in children and adolescents, reaches the level of an adult by about 20 years of age. The entire complex process of human GNI development is determined both by heredity and by many other biological and social environmental factors. The latter acquire leading importance in the postnatal period, so the family and educational institutions bear the main responsibility for the development of a person’s intellectual capabilities.
GNI of a child from birth to 7 years. A child is born with a set of unconditioned reflexes, the reflex arcs of which begin to form in the 3rd month of intrauterine development. Then the first sucking and breathing movements appear in the fetus, and active fetal movement is observed in the 4-5th month. By the time of birth, the child has formed most of the innate reflexes, which ensure the normal functioning of the vegetative sphere.
The possibility of simple food conditioned reactions arises already on the 1st-2nd day, and by the end of the first month of development, conditioned reflexes are formed from the motor analyzer and vestibular apparatus.
From the 2nd month of life, auditory, visual and tactile reflexes are formed, and by the 5th month of development, the child develops all the main types of conditioned inhibition. Child training is of great importance in improving conditioned reflex activity. The earlier training begins, that is, the development of conditioned reflexes, the faster their formation subsequently occurs.
By the end of the 1st year of development, the child is relatively good at distinguishing the taste of food, smells, shape and color of objects, and distinguishes voices and faces. Movements improve significantly, and some children begin to walk. The child tries to pronounce individual words, and he develops conditioned reflexes to verbal stimuli. Consequently, already at the end of the first year, the development of the second signaling system is in full swing and its joint activity with the first is being formed.
In the 2nd year of child development, all types of conditioned reflex activity are improved, and the formation of the second signaling system continues, vocabulary increases significantly; irritants or their complexes begin to cause verbal reactions. Already in a two-year-old child, words acquire signal meaning.
The 2nd and 3rd years of life are distinguished by lively orientation and research activities. This age of the child is characterized by the “objective” nature of thinking, i.e., the decisive importance of muscle sensations. This feature is largely associated with the morphological maturation of the brain, since many motor cortical zones and zones of musculocutaneous sensitivity already reach a fairly high functional usefulness by the age of 1-2 years. The main factor stimulating the maturation of these cortical zones is muscle contractions and high motor activity of the child.
The period up to 3 years is also characterized by the ease of formation of conditioned reflexes to a wide variety of stimuli. A notable feature of a 2-3 year old child is the ease of developing dynamic stereotypes - sequential chains of conditioned reflex acts, carried out in a strictly defined order, fixed in time. A dynamic stereotype is a consequence of a complex systemic reaction of the body to a complex of conditioned stimuli (conditioned reflex for time - eating, sleep time, etc.).
The age from 3 to 5 years is characterized by further development of speech and improvement of nervous processes (their strength, mobility and balance increase), the processes of internal inhibition acquire dominant importance, but delayed inhibition and conditioned inhibition are developed with difficulty.
By the age of 5-7 years, the role of the signal system of words increases even more and children begin to speak freely. This is due to the fact that only by the seven years of postnatal development the material substrate of the second signaling system, the cerebral cortex, functionally matures.
GNI for children from 7 to 18 years old. Junior school age (from 7 to 12 years) is a period of relatively “quiet” development of GNI. The strength of the processes of inhibition and excitation, their mobility, balance and mutual induction, as well as a decrease in the strength of external inhibition, provide opportunities for extensive learning of the child. But only when learning to write and read does the word become the object of the child’s consciousness, increasingly moving away from the images, objects and actions associated with it. A slight deterioration in GNI processes is observed only in the 1st grade in connection with the processes of adaptation to school.
The teenage period (from 11-12 to 15-17 years) is of particular importance for teachers. At this time, the balance of nervous processes is disturbed, excitation becomes more powerful, the increase in the mobility of nervous processes slows down, and the differentiation of conditioned stimuli significantly worsens. The activity of the cortex is weakened, and at the same time the second signaling system. All functional changes lead to mental imbalance and conflict in the adolescent.
Senior school age (15-18 years) coincides with the final morphofunctional maturation of all body systems. The role of cortical processes in the regulation of mental activity and the functions of the second signaling system is increasing. All properties of nervous processes reach the level of an adult, i.e., the GNI of older schoolchildren becomes orderly and harmonious. Thus, for the normal development of VNI at each individual stage of ontogenesis, it is necessary to create optimal conditions.
17. Features of the GNI of a mature and elderly person.
Age-related features of brain activity in humans during adulthood have been studied relatively little. The most systematic studies concernstudying the typological properties of the nervous system.
Teplov's research shows that there is a very large variability of typological features that are difficult to fit into four classical types. It has also been established that, along with the general type of the nervous system, there are “partial” (or partial) types that characterize the functional properties of a particular catalyst. So, for example, with a generally strong, balanced type of nervous system, a predominance of excitation can be detected in samples addressed to the auditory analyzer.
Zyryanova studied age-related characteristics of the properties of nervous processes in healthy adults of four groups: 1) 18-21 years old; 2) 22-24 years; 3) 25-28 years old and 4) 29-33 years old. For all groups, the author found that in women there is no correspondence in the level of excitability in auditory and visual motor reactions, while in men the correlations of these reactions reach a statistically significant level. Women are characterized by a high rate of closing positive connections, men by a high rate of development of differentiations. The correlation between indicators of the level of excitability (“sensitivity”) and the strength of nervous processes in the group of women turned out to be slightly higher than in the group of men at all ages studied, and the stability of these parameters in women appears earlier - already at 18-24 years old, while in men - 25-33 years old.
Quite a large number of studies are devoted to studyinginteraction of signaling systems in an adult.The great influence of verbal influences on orienting and motor conditioned reflexes has been shown. If a direct stimulus is given a signal value with the help of verbal instructions, this leads to a decrease in thresholds and a shortening of the latent periods of the components of the orienting reflex, which indicates an increase in the excitability of the corresponding parts of the central nervous system. Interestingly, a number of American psychologists are currently turning to conditioned reflex techniques to determine the functional level of brain activity.
8. An elderly person
Pavlov was keenly interested in the problem of changes in higher nervous activity in humans during aging, comparing data from individual clinical observations, sometimes from introspection, with results obtained on animals. He believed that with the onset of old age, the basic nervous processes weaken, especially the inhibitory ones, as well as their mobility decreases, and inertia of the process develops. Pavlov explained the weakening of the inhibition process as characteristic of old age in senile talkativeness and fantasticness.
One of the first manifestations of aging is the weakening of memory for current events, according to Pavlov’s observations, depending on a change in the mobility of the irritable process towards its inertia. Pavlov considered senile absent-mindedness to be a consequence of pronounced negative induction. Taking into account the data of self-observation, he wrote: “The further, the more I lose the ability, busy with one thing, to conduct another regularly. Obviously, concentrated stimulation of a certain point, with a general decrease in the excitability of the hemispheres, induces such inhibition of the remaining parts of the hemispheres that the conditioned stimuli of old, firmly fixed reflexes are now below the threshold of excitability.” Regarding the sequence of changes in the properties of nervous processes, he pointed out: “Based on our material, we can say that with aging, the inhibitory process first weakens, and then the mobility of the nervous process suffers, and inertia increases.
In elderly people, blinking conditioned reflexes are inhibited with relatively greater preservation of speech reactions. In old age, the opposite relationship took place. The systematic use of verbal and direct stimuli with a rest of 1-2 days contributed to the improvement of the functions of both signaling systems.
During the aging process, not only a disruption of the complex response was observed, but also a change in the properties of nervous processes. In people aged 60-90 years, conditioned motor reflexes were developed with electrocutaneous reinforcement.
When converting the signal values of an associated pair of conditioned stimuli into reverse ones, a particular difficulty was revealed in converting a positive conditioned reflex into an inhibitory one. All this speaks of inertia and weakening of the irritable process in old age.
A study of the mobility of the nervous processes of the speech system showed that during the experiment, the lengthening of the latent periods (up to 2 - 6 seconds) of verbal reactions was often accompanied by repeated responses. Objectively recorded movements of the lower jaw did not stop immediately after the verbal response, as in younger subjects, but continued for several seconds after it, which indicates the inertia of the irritative process in the speech motor analyzer.
In a number of elderly people studied, interest in the surrounding reality prevails over other unconditioned reflexes, and speech activity retains leading importance. Autonomic disorders in elderly people in the form of vascular unresponsiveness, changes in breathing that take on a wave-like character, apparently depend on the weakening of the regulatory function of the cerebral cortex.
18. Functional blocks of the brain.
General structural and functional model of the brain- concept brain How materialsubstratepsyche, developed A.R. Luriabased on the study of mental disorders in various local lesionscentral nervous system. According to this model, the brain can be divided into three main blocks, which have their own structure and role in mental functioning:
Energy
Reception, processing and storage of exteroceptive information
Programming, regulation and control of conscious mental activity
Each individual mental function is ensured by the coordinated work of all three blocks, with normal development. The blocks are combined into so-called functional systems, which represent a complex dynamic, highly differentiated complex of links located at different levels of the nervous system and taking part in solving various adaptive problems.
1st block: energy
Function energy blockconsists of regulating general changes in brain activation (tone brain level wakefulness ) and local selective activation changes necessary for the implementationhigher mental functions.
The energy block includes:
reticular formationbrain stem
nonspecific structuresmidbrain
diencephalic regions
limbic system
mediobasal sectionsbark frontal and temporal lobes
If a disease process causes a failure in the normal operation of the 1st block, then the consequence will be a decrease intonecerebral cortex. The person becomes unstableattention, pathologically increased exhaustion and drowsiness appear.Thinkingloses the selective, arbitrary character that it has innormal . The emotional life of a person changes, he either becomes indifferent or pathologically anxious.
2nd block: reception, processing, storage of exteroceptive information
Reception, processing and storage blockexteroceptive information includes the central parts of the mainanalyzers - visual, auditory And skin-kinesthetic. Their cortical zones are located in the temporal, parietal and occipital lobes of the brain. Formally, the central parts can also be included here.gustatory And olfactory modality, however, in the cerebral cortex they are represented insignificantly compared to the main sensory systems.
This block is based on the primary projection zones of the cerebral cortex, which perform the task of stimulus identification. The main function of the primary projection zones is the subtle identification of the properties of the external and internal environment at the level of sensation.
Violations of the second block: within the temporal lobe - hearing may be significantly affected; damage to the parietal lobes - impaired skin sensitivity,touch(it is difficult for the patient to recognize an object by touch, the sense of normal body position is disrupted, which entails a loss of clarity of movements); lesions in the occipital region and adjacent areas of the cerebral cortex - the process of receiving and processing visual information worsens. Modal specificity is a distinctive feature of the work of the brain systems of the 2nd block.
3rd block: programming, regulation and control
Programming, regulation and control unitover the course of conscious mental activity, according to the conceptA. R. Luria, is engaged in the formation of action plans. Localized in the anterior parts of the cerebral hemispheres, located in front of the anterior central gyrus (motor, premotor, prefrontal parts of the cerebral cortex), mainly infrontal lobes.
Lesions in this part of the brain lead to disorders of the musculoskeletal system, movements lose their smoothness, and motor skills disintegrate. At the same time, information processing and speech do not undergo changes. With complex deep damage to the frontal cortex, relative preservation of motor functions is possible, but a person’s actions cease to obey given programs. Purposeful behavior is replaced by inert, stereotypical or impulsive reactions to individual impressions.
19. The concept of a functional system.
Functional systems theory, proposed by P.K. Anokhin, postulates a fundamentally new approach to physiological phenomena. It changes traditional “organ” thinking and opens up a picture of the holistic integrative functions of the body.
Having emerged on the basis of I.P. Pavlov’s theory of conditioned reflexes, the theory of functional systems was its creative development. At the same time, in the process of developing the theory of functional systems itself, it went beyond the framework of the classical reflex theory and took shape into an independent principle of organization of physiological functions. Functional systems have a cyclic dynamic organization different from the reflex arc, all the activities of the constituent components of which are aimed at providing various adaptive results useful for the body and for its interaction with the environment and its own kind. Any functional system, according to the ideas of P.K. Anokhin, has a fundamentally similar organization and includes the following general peripheral and central nodal mechanisms, which are universal for different functional systems:
A useful adaptive result as a leading link in a functional system;
Result receptors;
Reverse afferentation coming from the result receptors to the central formations of the functional system;
Central architectonics, representing the selective unification by a functional system of nervous elements of various levels;
Executive somatic, autonomic and endocrine components, including organized goal-directed behavior.
From a general theoretical point of view, functional systems are self-regulating organizations that dynamically and selectively unite the central nervous system and peripheral organs and tissues on the basis of nervous and humoral regulation to achieve adaptive results useful for the system and the organism as a whole. Adaptive results that are useful for the body are, first of all, homeostatic indicators that provide various aspects of metabolic processes, as well as the results of behavioral activity located outside the body that satisfy various biological (metabolic) needs of the body, the needs of zoosocial communities, and the social and spiritual needs of humans.
Functional systems are built primarily by the current needs of living beings. They are constantly formed by metabolic processes. In addition, the functional systems of the body can develop under the influence of special environmental factors. In humans, these are primarily factors of the social environment. Memory mechanisms can also be the cause of the formation of functional systems, especially at the behavioral and mental levels.
The combined activity of many functional systems in their interaction determines the complex processes of homeostasis of the organism and its interaction with the environment.
Functional systems thus represent units of integrative activity of the organism.
20. Functional system of behavioral act.
Functional system is a concept developedPC. Anokhinand appearing in his theory of constructionmovementas a unit of dynamic morphophysiological organization, the functioning of which is aimed at adapting the organism. This is achieved through mechanisms such as:
1. Afferentsynthesisincoming information;
2.
Decision-makingwith the simultaneous construction of an afferent model of the expected result - an acceptor of the results of the action;
3. Real implementation of the decision inaction;
4. Organization of reverse afferentation, due to which it becomes possible to compare the forecast and the results of the action.
The afferent synthesis stage ends with a transition to the decision-making stage, which determines the type and direction of behavior. In this case, a so-called acceptor of the result of an action is formed, which is an image of future events, a result, a program of action and an idea of the means of achieving the desired result. At the stage of efferent synthesis, a specific program of behavioral act is formed, which turns into action - that is, which side to run from, which paw to push and with what force. The result of the action received by the animal is compared in its parameters with the acceptor of the result of the action. If a coincidence occurs that satisfies the animal, the behavior in that direction ends; if not, the behavior resumes with the changes necessary to achieve the goal. For example, if a Scotch Terrier cannot reach the sausage lying on the table, the goal has not been achieved, it is necessary to change the strategy, he tries to jump, if this does not work, then he jumps onto a stool, from there onto the table and, satisfied, with the sausage in The mouth goes to a secluded place to deal with the prey.
Emotions play a major role in goal-directed behavior - both those associated with the emergence and intensification of needs, and those arising in the process of activity (reflecting the likelihood of achieving a goal or the results of comparing actual results with expected ones).
In contrast to the reflex theory, the theory of functional systems puts forward the following principles:
1. The behavior of living beings is determined not only by external stimuli, but also by internal needs, genetic and individual experience, and the action of environmental stimuli, which create the so-called pre-trigger integration of excitations, revealed by trigger stimuli.
2. The behavioral act unfolds ahead of the actual results of behavior, which allows you to compare what was actually achieved with what was planned, based on past experience, and adjust your behavior.
3. A purposeful behavioral act ends not with an action, but with a useful adaptive result that satisfies a dominant need.
21. Methods for obtaining experimental neuroses. Relationship between neurotic disorders and psychological characteristics.
In the laboratory of I.P. Pavlov, it was possible to induce experimental neuroses (functional disorders of the central nervous system) using overstrain of nervous processes, which was achieved by changing the nature, strength and duration of conditioned stimulation.
Neuroses can occur:1) when the excitation process is overstrained due to the use of a long-term intense stimulus; 2) when the inhibitory process is overstrained by, for example, prolonging the period of action of differentiating stimuli or developing subtle differentiations into very similar figures, tones, etc.; 3) when the mobility of nervous processes is overstrained, for example, by converting a positive stimulus into an inhibitory one with a very rapid change of stimuli or by simultaneously converting an inhibitory conditioned reflex into a positive one.
With neuroses, a breakdown of higher nervous activity occurs. It can be expressed in a sharp predominance of either an excitatory or inhibitory process. When excitation predominates, inhibitory conditioned reflexes are suppressed and motor excitation appears. When the inhibitory process predominates, positive conditioned reflexes are weakened, drowsiness occurs, and motor activity is limited. Neuroses are especially easily reproduced in animals with extreme types of nervous system: weak and unbalanced.
The essence of neurosis is a decrease in the performance of nerve cells. Often, with neuroses, transitional (phase) states develop: equalizing, paradoxical, ultraparadoxical phases. Phase states reflect violations of the law of force relations characteristic of normal nervous activity.
Normally, there is quantitative and qualitative adequacy of reflex reactions to the current stimulus, i.e. to a stimulus of weak, medium or strong strength, a correspondingly weak, medium or strong reaction occurs. In neurosis, an equalizing phase state is manifested by reactions of equal severity to stimuli of different strengths, a paradoxical state is manifested by the development of a strong reaction to a weak influence and weak reactions to strong influences, an ultraparadoxical state is manifested by the occurrence of a reaction to an inhibitory conditioned signal and the loss of a reaction to a positive conditioned signal.
With neuroses, inertia of nervous processes or their rapid exhaustion develops. Functional neuroses can lead to pathological changes in various organs. For example, skin lesions such as eczema, hair loss, disruption of the digestive tract, liver, kidneys, endocrine glands and even the occurrence of malignant neoplasms occur. Diseases that existed before the neurosis become aggravated.
22.Disturbances of human higher nervous activity.
The origin of many diseases of the nervous system turned out to be associated with functional disturbances of the normal properties of the basic nervous processes and higher nervous activity. The nature of these disorders was explained in the study of experimental neuroses that arise when the excitatory and inhibitory processes are overstrained or when they collide.
Overstrain of the excitatory process by the action of “super-strong” stimuli was clearly demonstrated in dogs kept at the Institute of Experimental Medicine that survived the 1924 flood in Leningrad. Even after the restoration of conditioned reflexes, they could not respond normally to strong stimuli, especially those associated with the shock they had experienced.
Neurotic disorders of higher nervous activity manifest themselves in a wide variety of forms, of which the most characteristic is the chronic development of these disorders in the form of chaotic conditioned reflexes or cyclical changes in their level, the emergence of phase states with equalizing and paradoxical phases, explosiveness and pathological inertia of nervous processes. A neurotic breakdown is easier to cause in a weak and unrestrained type of nervous system, and in the first case the excitatory process suffers more often, and in the second - the inhibitory process. Pictures of neurotic breakdowns in people are also explained in connection with the specific features of the typology of their higher nervous activity.
Experimental neuroses are accompanied by disorders of autonomic functions, which reflects the functional connection of the cerebral cortex and internal organs. Profound disturbances of higher nervous activity as a result of a “collision” of nervous processes have been described. At the same time, the acidity of the gastric juice increased, gastric atony occurred, the secretion of bile and pancreatic juice increased without a corresponding change in blood supply, a persistent increase in blood pressure was observed, and the activity of the kidneys and other systems was disrupted. The study of experimental neuroses in animals gave impetus to the development of such a direction in medicine as cortico-visceral pathology (K. M. Bykov, M. K. Petrova).
In the light of these ideas, many questions of the etiology and pathogenesis of peptic ulcer and hypertension, premature aging and some others are explained. To restore the normal state of higher nervous activity after developing neurosis, sometimes a long rest in a change of environment, as well as normal sleep, is sufficient. Pharmacological agents of selective action on excitatory and inhibitory processes (caffeine and bromine) are used depending on the state of the central nervous system and the nature of the neurotic breakdown.
I. P. Pavlov’s teaching on higher nervous activity made it possible to decipher many mechanisms of mental disorders and human behavior. The most important thing is that this teaching did not leave room for idealistic interpretations of the nature of psychic phenomena, ideas about the “soul”; it was the result that revealed the nature of the most complex and from time immemorial psychic phenomena that seemed mysterious. The teachings of I.P. Pavlov became the natural scientific basis of materialist psychology, pedagogy and Lenin’s theory of reflection.
23. The concept of the sensory system. Structural and functional organization of analyzers. Properties of analyzers.
Information about events occurring in the external environment and the state of internal organs comes to the central nervous system from specialized formations - receptors or special reception organs. Each receptor is only part of a system called an analyzer.
The analyzer is a system consisting of three sections, functionally and anatomically connected to each other: the receptor, the conductive section and the central section in the brain. The highest department of any analyzer is the cortical department, which has a nucleus and neurons scattered in various parts of the cortex. The simplest forms of stimulus analysis occur in receptors. Impulses from them enter the brain along the conduction pathway, where higher analysis of information occurs.
Reception organs are actually receptor nerve endings or receptor nerve cells enclosed in a capsule, sheath or special additional terminal formations. Types of receptors: contact and distant. Exteroceptors (external receptors): visual, auditory, tactile, gustatory, olfactory; Interoreceptors (internal): visceroreceptors, vestibuloreceptors, proprioceptors (muscles, tendons). According to the mechanism of action, they are distinguished: mechanoreceptors, photoreceptors, baroreceptors, chemoreceptors, thermoreceptors.
Receptors perceive information from the stimulus, encode it and transmit it in the form of impulses (sensory code). The receptor organ is capable of not only receiving, but also amplifying the signal due to its own internal energy - the energy of metabolic processes.
Most receptors are characterized by the property of becoming accustomed to a constantly acting stimulus. This property is called adaptation. With prolonged constant stimulation, adaptation manifests itself in a drop in the level of excitation, a decrease, and then the complete disappearance of the generator potential. Adaptation can be complete or incomplete, as well as fast or slow. However, the receptor retains the ability to respond to any change in stimulation parameters.
Thus, the selection of information is carried out at the level of the receptor, from where the information is sent in the form of a nerve impulse that is uniform in nature. Further processing and analysis of information is provided in the central nervous system. Here it is stored and used in the process of life to form the body's response. Human thinking and mental activity are ultimately a consequence of the ability of the central nervous system to operate with information presented and encoded in a complex mosaic of nerve impulses reproduced in various parts of the brain.
24. Visual analyzer.
The visual analyzer consists of the peripheral region, subcortical visual centers and the occipital region of the cerebral cortex, interconnected by pathways. The human eye has a spherical shape and is located in the orbit. It has optical and receptor systems. The optical system consists of the cornea, anterior chamber humor, lens and vitreous body. The receptor system consists of the retina, which converts the optical signal into bioelectric reactions and carries out the primary processing of visual information. The photoreceptor cells of the retina - cones and rods - have different sensitivity to light and color.
25. Hearing analyzer.
Perceiving periodic vibrations of air, the auditory analyzer transforms the mechanical energy of these vibrations into nervous excitation, which is subjectively reproduced as a sound sensation. The peripheral part of the auditory analyzer consists of the outer, middle and inner ear. The outer ear consists of the pinna, external auditory canal and eardrum. The middle ear contains a chain of interconnected bones: the malleus, the incus and the stapes. The stapes has a mass of 2.5 mg and is the smallest bone in the body. The inner ear is connected to the middle ear through the oval window and contains receptors for two analyzers - vestibular and auditory.
26. Vestibular, motor analyzers.
, spinal cord , cerebral cortex And cerebellum. Thanks to the vestibulo-ocular reflexes, gaze fixation is maintained during head movements.
27. Skin, internal analyzers.
Skin analyzer,a set of anatomical and physiological mechanisms that provide the perception, analysis and synthesis of mechanical, thermal, chemical and other irritations falling from the external environment onto the skin and some mucous membranes (oral and nasal cavity, genitals, etc.). Like othersanalyzers, K. a. consists of receptors, pathways that transmit information to the central nervous system (CNS), and higher nerve centers in the cerebral cortex. K. a. includes different types of skin sensitivity: tactile (touch and pressure), temperature (heat and cold) and pain (nociceptive). There are over 600 thousand touch and pressure receptors (mechanoreceptors) that perform the function of touch in human skin. The sensation of heat and cold occurs when thermoreceptors are irritated, of which there are about 300 thousand, including about 30 thousand thermal receptors.
The issue of independent pain reception has not yet been resolved: some recognize the presence in the skin of 4 types of receptors - heat, cold, touch and pain - with separate impulse transmission systems; others believe that the same receptors and conductors can be painful and non-painful, depending on the strength of irritation. Among the skin receptors there are free nerve endings, usually considered as pain receptors; tactile corpuscles of Meissner and Merkel, corpuscles of Golgi - Mazzoni and Vater - Pacini (pressure receptors), end flasks of Krause (cold receptors), corpuscles of Rufini (heat receptors), etc. These receptors, with the exception of pain ones, easily adapt to irritations, which is expressed in decreased sensitivity. Nerve fibers from skin receptors in the central nervous system differ in structure, thickness and speed of impulses: the thickest transmit mainly tactile sensitivity at a speed of 50-140 m/sec. Temperature sensitivity fibers are somewhat thinner, conduction speed is 15-30 m/sec, thin fibers lack a myelin sheath and conduct impulses at a speed of 0.6-2 m/sec. Sensitive pathways K. a. pass through the spinal cord and medulla oblongatavisual cusps, associated with the posterior central gyrus of the parietal region of the cerebral cortex, where nervous excitation turns intofeeling. From all sensory pathways going to the brain, branches extend intoreticular formationbrain stem. Under normal conditions, skin irritations are not perceived separately. Sensations are formed in the form of complex holistic reactions. Different parts of the central nervous system andautonomic nervous system. The nature (modality) and emotional coloring of the sensations that arise as a result of the activity of K. depend on their state and interaction.
28. Taste and olfactory analyzers.
OLfactory ANALYZER
In humans, the olfactory organs line the middle part of the superior turbinate and the corresponding areas of the mucous membrane of the nasal septum. A process, an axon, extends from the receptor cells, which transmits information about odors to the primary centers of smell - the olfactory bulbs. Prolonged exposure to any odor after some time causes a deterioration in its perception. In the bulb, the primary processing of information coming from receptor cells occurs and then, as part of the olfactory nerve, it is sent to the cortical formations.
TASTE ANALYZER
Taste budsare located in taste buds - round receptor cells grouped like lemon slices. Taste buds are located inpapillae of the tongue(leaf-shaped papillae of the tongue - on the lateral edges of the tongue, mushroom-shaped papillae of the tongue - on its back, gutter-shaped papillae of the tongue - on the border of the back and root of the tongue), as well as in the mucous membrane of the soft palate, epiglottis, pharynx and esophagus. All taste buds are built the same way. At the apex of the bud there is a taste pore into which microvilli of receptor cells protrude. These microvilli are locatedtaste buds; at least five types are known. The signal transduction mechanisms in taste buds are different for different taste sensations. Unlikebipolar cellsolfactory epitheliumtaste receptor cells are not neurons. From taste receptor cells, excitation is transmitted to the endingsfacial, glossopharyngeal And vagus nerve .
There are four so-called basic taste qualities: sweet, salty, sour and bitter. Individual afferent fibers in most cases respond to several taste substances, but taste fibers differ in sensitivity to these substances and can be divided into several groups. For example, in neurons that are predominantly sensitive to sucrose, sensitivity to table salt almost always comes in second place. The fact that individual afferent taste fibers are sensitive to a wide range of taste stimuli formed the basis of the theory of coding by spatial pattern of impulses (each taste sensation corresponds to a specific pattern of impulses in parallel afferent fibers).
The second theory suggests that each taste sensation corresponds to a specialized afferent fiber or group of fibers. Currently, these two hypotheses are no longer considered contradictory: gross and subtle differences in tastes are encoded in the body according to different principles. For example, to determine sweet taste, neurons that are predominantly sensitive to sucrose are sufficient, but the discrimination between sucrose and fructose is carried out based on the difference in impulses from neurons that are predominantly sensitive to sucrose, table salt and quinine. As for the intensity of sensation, it, as in other sensory systems, is determined by the quantitative characteristics of the impulse.
29. Pain analyzer.
Pain reception is of great importance for the body. Pain develops when tissue is damaged and is a warning mechanism. Pain receptors are free nerve endings scattered throughout the body. A number of tissues do not have numerous pain endings (periosteum, arterial walls, pericardium, etc.). However, extensive damage to such tissues results in intense aching pain. The bodies of the first neurons responsible for the perception of pain are located in the spinal ganglia. Their axons enter the spinal cord as part of the dorsal roots and extend within six segments, ending on the second neurons in the dorsal horns of the spinal cord. The axons of these neurons constitute the ascending fibers into the brain (hindbrain, thalamus).
SYMPTOMS OF IRRITATION
Symptoms of irritation are manifested by a variety of sensations, which patients themselves call tingling, aching, burning, pulling, pressing, tightening, shooting, twisting, sore, stabbing, electric shock, etc. Such sensations are not always perceived aspain. It is believed that the basis for the occurrence of symptoms of irritation is the generation of pathological discharges in structures with increased excitability, localized somewhere in the peripheral or central partssensory systems. The nature of the sensations depends on the frequency and other temporal characteristics of such discharges, their spatial distribution, as well as on the structures in which they occur. Symptoms of irritation - a manifestation of increased activity of structuressensory systems. Symptoms of irritation may occurparesthesia(a false sensation that occurs without external stimuli) anddysesthesia(a more general concept that also includes perverted perception of external stimuli).
30. Forms of learning.
Can be distinguished three main types of learning:development of reactive forms of behavior, development of operant behavior and cognitive learning.
Production of reactive forms of behavior comes down to the fact that the brain passively perceives external influences and this leads to changes in existing and the formation of new neural connections.
Habituation and sensitization lead to a change in the “alertness” reaction: in case of addiction it decreases, and in case of sensitization it increases. In imprinting, which occurs in some animal species, a permanent imprint is formed in the baby's brain when it perceives the first moving object. Concerningconditioned reflexes,then they are produced when an unconditioned stimulus (stimulus) is associated with an indifferent stimulus; in this case, the latter begins to cause a reflex reaction on its own, and is now called a conditioned stimulus.
Learning operant forms of behavior occurs when an individual makes some kind of impact on the environment, and depending on the results of such actions, this behavior is reinforced or discarded.
Method learning trial and error consists in the fact that the individual repeats actions whose results give him satisfaction and discards other behavioral reactions. Learning byreaction formation isa sort of systematic application of trial and error; the individual is led to form a final behavioral response by reinforcing each action that brings him closer to the desired end result.
Reinforcements a stimulus (or event) is called, the presentation or elimination of which increases the likelihood of repetition of a given behavioral reaction. Reinforcement is called positive or negative depending on whether it consists of the presentation or, conversely, the removal of a certain stimulus. Atprimary reinforcementsome physiological need is directly satisfied, and secondary reinforcers provide satisfaction because they are associated with primary (or other secondary) factors.
Reinforcement (positive or negative) increases the likelihood of repetition of the behavioral reaction; against, punishment - this is an unpleasant event, each time caused by a given behavior, and therefore it leads to disappearance such behavior. Fading consists of the gradual cessation of a behavioral response if it is not followed by an unconditioned stimulus or reinforcer.
At differentiationreactions to those stimuli that are not accompanied by an unconditioned stimulus, or non-reinforced reactions, are inhibited, and only those that are reinforced are retained; on the contrary, when generalization a behavioral response is caused by any stimulus similar to the conditioned one (or the response occurs in any situations similar to the one in which the reinforcement occurred).
Learning by observationmay come down to simple imitation, or maybe vicar learning; in the latter case, the model’s behavior is reproduced depending on the consequences it had for it.
In cognitive forms of learning, an assessment of the situation occurs in which higher mental processes are involved; In this case, both past experience and analysis of available opportunities are used, and as a result, an optimal solution is formed.
Latent learning is a type of cognitive learning in which cognitive maps are formed in the brain, reflecting the meaning of various stimuli and the connections that exist between them. When mastering complexpsychomotor skillsCognitive strategies are developed that allow you to program actions.
When learning by insight the solution to a problem comes suddenly through the combination of experience accumulated by memory and information coming from outside. Learning by reasoning includes two stages: at the first of them, the available data and connections between them are taken into account, and at the second, hypotheses are formed, which are subsequently tested, and as a result a solution is found. In concept learning, the subject discovers similarities between different objects, living beings, situations, or ideas and forms an abstract concept that can be extended to other objects with similar features.
Learning is closely related to maturation body. Maturation is a process programmed in genes in which all individuals of a given species, having gone through a series of similar sequential stages, reach a certain level of maturity. This level may be different for different organs and functions.Critical periods -These are periods in the development of an individual during which certain types of learning are more easily accomplished.
When assessing effectiveness learning should take into account in each specific case a number of perceptual and emotional factors, as well as the state of consciousness of the subject. Therefore, such an assessment rarely reflects its actual capabilities. In addition, the quality of learning and its results are closely related to the subject’s previous experience; the transfer of these experiences can either facilitate or slow down the development of new knowledge or skills.
- cribs Types of sensory systems. Principles of information coding in sensory systems.
Somatic sensory system.
Principles of organization of motor systems.
The role of the motor cortex in the...- 94.89 KB
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16 lectures on 79 pages
The subject and tasks of physiology, its connections with other disciplines. A brief history of the development of physiology as a science. Methods of physiology. General plan of the structure of the nervous system and its physiological significance. Basic physiological concepts.
The concept of excitable tissues. Excitation. Excitability. Conductivity...
