The first theoretical concept of the reflex arc belongs to. Founder of reflex theory Rene Descartes

So, Sechenov was the first to formulate the reflex theory. Its main provisions are as follows:

A reflex is a unique universal form of interaction between an organism and its environment, based on evolutionary biology. Sechenov identified two types of reflexes:

Constant, congenital, which are carried out by the lower parts nervous system(“pure” reflexes).

Changeable, acquired in individual life, which he considered both physiological and mental phenomena.

The activity of nerve centers is represented as a continuous dynamics of the processes of excitation and inhibition.

Brain centers can delay or enhance spinal cord reflexes.

Sechenov introduces the concept of the “physiological state of the nerve center,” which is directly related to biological needs. The state of the center represents the nervous substrate of need.

The concept of “reflex association” is introduced, which underlies the learning of humans and animals.

However, Sechenov did not have enough experimental confirmation of his “brilliant guesses.” Pavlov experimentally confirmed and supplemented Sechenov’s ideas. He supported Sechenov's ideas scientific concept conditioned reflex, introduced it into the strict framework of laboratory experiment. We can highlight the following most important achievements of Pavlovian theory:

A laboratory method for objectively studying the adaptive activity of humans and animals (the method of conditioned reflexes) has been created.

The adaptive-evolutionary meaning of conditioned reflexes for the animal world is emphasized.

An attempt was made to localize the process of temporary connection closure in the cortex cerebral hemispheres.

I noted the presence of b.p. in the cortex. braking process.

The doctrine of analyzers is clearly formulated (3 blocks in the structure of any sensory system).

Formulated the idea of ​​the cortex as a mosaic of processes of excitation and inhibition.

At the end of his life he put forward the principle of systemic functioning of the brain.

So, the basic principles of the Pavlov-Sechenov reflex theory are as follows:

The principle of determinism (causality). This principle means that any reflex reaction is causally determined, that is, there is no action without a reason. Every activity of the body, every act of nervous activity is caused by a certain influence from the external or internal environment.

The principle of structure. According to this principle, each reflex reaction is carried out using certain brain structures. There are no processes in the brain that do not have a material basis. Each physiological act of nervous activity is associated with some structure.

The principle of analysis and synthesis of stimuli. The nervous system constantly analyzes (distinguishes) with the help of receptors all external and internal stimuli acting on the body, and on the basis of this analysis forms a holistic response - synthesis. In the brain, these processes of analysis and synthesis occur continuously and constantly. As a result, the body extracts the information it needs from the environment, processes it, records it in memory and forms response actions in accordance with circumstances and needs.

Another important concept in the physiology of VND is the concept of nervism - this is a concept that recognizes the leading role of the nervous system in regulating the functions of all organs and tissues of the body. A great contribution to the development of the concept of nervism was made by I.M. Sechenov and especially Botkin S.P. (1832-1889). Botkin considered various diseases as consequences of disturbances of normal nervous regulation (clinical nervism).

Lecture 1

SUBJECT, TASKS, basic concepts and methodological principles of VND PHYSIOLOGY

Plan

Prerequisites for the emergence of I.P. Pavlov’s teaching on the physiology of VNI.. 1

Basic principles of reflex theory. 2

Subject, tasks and basic concepts of the physiology of GNI.. 3

Current state of the physiology of higher nervous activity. 4

The place of GNI physiology among the natural and human sciences. 5

Methods for studying higher nervous activity. 5

Prerequisites for the emergence of I.P. Pavlov’s teaching on the physiology of GNI

the creation of the materialistic doctrine of GNI is associated with the name of I.P. Pavlov. His research in the field of blood circulation and digestion paved the way for the transition to the study of complex function body - mental activity.

The formation of I.P. Pavlov’s physiological views was greatly influenced by the ideas developed by the founder of Russian medicine S.P. Botkin. Considering the human body in relation to the external environment, presenting the body’s activity as reflex, Botkin emphasized the leading role of the nervous system in regulating the functions of the body, maintaining its integrity and adaptation to the environment.

In the development of GNI issues, I.P. Pavlov’s ideological inspirer was I.M. Sechenov. For the first time in the history of natural science, he expressed the idea that consciousness is only a reflection of real reality and knowledge surrounding a person environment is possible only with the help of the senses, the products of which are the original source of all mental activity. I.M. Sechenov wrote that all acts of conscious and unconscious life, according to the method of origin, are reflexes.

According to I.M. Sechenov, a thought is a “mental reflex with a delayed ending,” and a “mental reflex with an enhanced ending” is what is usually called an emotion. Thanks to the “mental element,” an integral part of the reflex process, the body can actively adapt to the environment, self-regulate, exhibiting a wide variety of behavioral reactions.

The progress of the psyche, according to Sechenov, is due to the improvement of the nervous organization of the brain, its phylo- and ontogenetic development and is carried out according to the principle of complication of the associative process. I.M. Sechenov connects four categories of mental activity with the activity of the cerebral hemispheres: instincts as an internal urge, meaningful feeling, meaningful movement and coordination of two latest categories into meaningful action or behavior.

The discovery of one of the fundamental mechanisms of brain activity - central inhibition, as well as experimental facts allowed I.M. Sechenov to postulate the existence of three main mechanisms that form the integral activity of the brain. This:

1. the activity of analyzers that ensure the transformation of environmental influences into nervous signals, their processing and transmission to the executive organs;

2. mechanisms of central inhibition;

3. the activity of special “reinforcement stations” of reflex acts.

Developing Sechenov's ideas, Pavlov discovered a completely special class of manifestations of the brain - conditioned reflexes. It is in these reflexes that the individual experience of higher living beings is consolidated and realized, from elementary behavioral acts to a grandiose system of specifically human speech signals.

Basic principles of reflex theory

The essence of Pavlovian teaching is not the unilateral influence of the environment on the body, but active interaction. Active interaction between the body and the environment is carried out according to the reflex principle. Balancing the body with the external environment is carried out thanks to the unconditional reflex activity of the nervous system. Unconditioned reflexes are excited by both internal and external agents, which determines the perfection of balancing. Since the external environment, despite its extreme diversity, is at the same time in constant fluctuation, unconditioned reflexes are not enough. There is a need to supplement them with conditioned reflexes.

Conditioned reflexes are a universal adaptive mechanism that provides plastic forms of behavior. The basis of the adaptive variability of the organism is the coordination of functions, carried out with the help of reflex, in turn, strictly coordinated activity of the brain.

Thus, a reflex is not a once and for all given, super-rigid act, but an integral self-regulating system. The flexibility of the reflex manifests itself where there is a discrepancy between the action and the cause that caused it. Inadequate reflex ratio external factors is that the determinants of the reflex are not only current external influences, but also the internal state of the body. One of the most important mechanisms for the internal determination of the reflex activity of the body is needs and associated motivational behavior.

I.P. Pavlov formulated three principles of reflex theory.

1. The principle of determinism (principle of causality), according to which any reflex reaction is causally determined. “There is no action without a reason.” Every activity of the body, every act of nervous activity is caused by a specific cause, influence from the external world or the internal environment of the body. The appropriateness of the reaction is determined by the specificity of the stimulus, the sensitivity of the body to stimuli.

2. The principle of structure the essence of which is that each reflex reaction is carried out with the help of certain structures, and the more structural elements are involved in the implementation of this reaction, the more perfect it is. There are no processes in the brain that do not have a material basis; every physiological act of nervous activity is confined to the structure.

3. The principle of unity of the processes of analysis and synthesis as part of a reflex reaction (the nervous system analyzes, i.e. distinguishes, with the help of receptors, all acting external and internal stimuli and, based on this analysis, forms a holistic response - synthesis). The brain continuously analyzes and synthesizes both incoming information and responses. As a result, the body extracts from the environment useful information, processes it, records it in memory and forms response actions in accordance with circumstances and needs.

Subject, tasks and basic concepts of the physiology of GNI

Physiology of higher nervous activity is the science of the brain mechanisms of behavior and psyche, which are based on the reflex theory.

Subject Physiology of GNI 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, controlling behavior and increasing the productivity of animals.

Main tasks physiology of GNI are:

· disclosure of the patterns of brain function;

· knowledge of the internal mechanisms of higher mental functions.

The central concepts in the physiology of VND are the unconditioned and conditioned reflex.

Unconditioned reflex- this is an innate species-specific reaction of the body, reflexively arising in response to the specific influence of a stimulus, a biologically significant stimulus (pain, food, cold, etc.), adequate for a given type of activity. Unconditioned reflexes are associated with vital biological needs and are carried out within a stable reflex pathway.

Conditioned reflex is an individually acquired reaction of the body to a previously indifferent stimulus, reproducing an unconditioned reflex. The conditioned reflex is based on the formation of new or modification of existing neural connections that occur under the influence of changes in the external and internal environment. These are temporary connections that are inhibited when reinforcement is canceled or the situation changes.

In the process of animal evolution and the phylogenetic development of brain structures, the ratio of innate and acquired reactions naturally changes: in the behavior of invertebrates and lower animals, innate forms of activity predominate over acquired ones, and in more developed animals individually acquired forms of behavior begin to dominate, which continuously develop, become more complex and improve. Based on this, I.P. Pavlov introduces a separation of the concepts of higher nervous activity and lower nervous activity.

Higher nervous activity- this is the conditioned reflex activity of the leading parts of the brain (in humans and animals - the cerebral hemispheres and forebrain), providing adequate and the most perfect behavioral reactions.

Lower nervous activity- this is the activity of the lower parts of the brain and spinal cord, which are mainly in charge of the relationships and integration of parts of the body with each other.

The rapid development of physiology and biology, discoveries in psychophysics and psychophysiology also stimulated the development of an anatomical and morphological model of the reflex, which filled the rather speculative concepts of Descartes and Hartley with real content.

In the works of the psychophysiologist and doctor I. Prochazka, the “general sensory” was discovered - the area of ​​​​the brain where the nerves originate, the irritation of which causes a transition from sensation to the body’s motor response to an external impulse, i.e. from sensory (sensory, centripetal) nerves to motor (motor, centrifugal). More low levels The innervations of behavior that he wrote about are related to the work not of the brain, but of the spinal cord, which is involved in the organization of elementary forms of behavior, a kind of automatisms, which, however, do not act purely mechanically, but according to the biological needs of the body.

The study of the reflex system was continued in the works of the English anatomist and physiologist C. Bell and the French scientist F. Magendie, who identified fibers running from the roots through the spinal cord to the fibers that activate the muscular apparatus. Thus, the model of the reflex was defined as a kind of automaton, consisting of three blocks: centripetal, central and centrifugal. This anatomical and morphological model of the central nervous system was called the Bell-Magendie law. This law describes the pattern of distribution of nerve fibers in the roots of the spinal cord: sensory fibers enter the spinal cord as part of the dorsal roots, and motor fibers enter the anterior roots.

Research by I.M. Sechenov systematized previous concepts, transforming the reflex system in accordance with experimental data of physiology. In the structure of the analyzer, he identified three parts - centripetal, i.e. sensing receptor central part, processing information, and centrifugal, transmitting signals to the muscle. An important point for the modern understanding of the reflex, the image put forward by Sechenov is a signal that not only “triggers” the reflex, but also regulates its course. In other words, it is not the external stimulus, but its reflection in the sense organ that is the signal that triggers the reflex act. In this case, the signal (i.e., the image of an object or situation), which allows one to distinguish the properties of objects in the external environment, directs and corrects the course of the reflex, optimizing its course.

In the central part, several information processing centers are distinguished, the main of which are: the center of inhibition (volitional regulation), information storage (memory), warning (thinking) and signal amplification (emotions).

Having put forward the principle of “coordinating movement with feeling,” Sechenov fundamentally revised the role of muscle efforts in the reflex act. His idea that the muscular sense contains a system of signals about the spatiotemporal parameters of the external world has been proven by a significant number of works by modern psychologists and physiologists. Thus, a muscle is not only an organ of movement, but also an organ of cognition, since objective actions are external analogues of certain mental operations (analysis, synthesis, classification, etc.), helping the formation of internal, actually mental operations.

Sechenov’s thoughts about feedback (i.e., signals from muscles to sensory organs) for self-regulation of behavior were developed by N.A. Bernstein, who studied the mechanisms of movement construction.

Bernstein showed that the automatic execution by muscles of commands sent by nerve centers cannot form the basis of a complex movement, since it is continuously corrected during execution. This occurs due to the fact that there is a cyclic connection between the muscle and the center. From the centers, signals are sent to the periphery in advance (Bernstein called them sensory corrections), which reflect the final result, according to the changing situation.

That is, the body, while working, solves a motor problem. In this case, there are five different levels of movement construction. Each level has its own, in its language, “afferent syntheses.” This means that in the nerve centers there is, as it were, encoded information that carries information in advance about the external world, in the space of which one or another class of movements is to be performed - “advanced reflection”. Thanks to this, the body is able to anticipate and predict the conditions in which it will have to act in the future, and not just store information about the past and respond to stimuli that affect its nervous system at the moment.

The organism encounters the world already having a supply of projects for possible movements. The creation of these projects reveals the activity of the body, the ability to be creative, to create something new, to build, as Bernstein wrote, a model of the “required result.” Thus, the reflex model was finally formulated, while the most important reason for the activity was not direct action stimulus to the organs of its perception, but the preparation of a model of a possible future action.

In addition to the structure of the reflex act, scientists were also interested in the ways of its transformation, changes under the influence of training and education. The works of I.P. were of great importance for the psychological investigation of this problem. Pavlova and V.M. Bekhterev.

Having studied the patterns of the dynamics of nervous processes (inhibition, irradiation, concentration, etc.) that determine the external manifestations of behavior, scientists have identified two levels of reflex behavior - unconditioned (simple) and conditioned (or combined) reflexes. Having a biological basis, a conditioned reflex is formed on the basis of an innate, unconditional (a certain need, for example, for food, protection from harmful influences, etc.), and the body constantly learns to distinguish and differentiate signals. If the signal leads to success, i.e. is reinforced, a connection is formed between it and the body’s response, which becomes stronger with repetition. This is how a conditioned reflex arises and is reinforced.

The orienting reflex discovered by Pavlov, or, as he called it, the “What is it?” reflex was also of great importance. It lies in the fact that the body continually asks this question to the world around it, trying to find out the meaning of the situation in which it finds itself and in the best way to “calculate” what is of the greatest value to it. The orienting reflex not only helps adapt to an unfamiliar environment, but is also the biological basis of any cognitive motivation, stimulating interest in unfamiliar, new stimuli.

By studying the biological mechanisms of reflex activity, Bekhterev proved that the flexibility and plasticity of the nervous system makes it possible to change reflexes of any degree of complexity in the desired direction. That is, in the behavior of living beings, inherited reflexes play a minimal role, while the leading one belongs to acquired, conditioned ones.

REFLECTOR THEORY(lat. reflexus turned back, reflected) is one of the main theoretical concepts of physiology and medicine, in accordance with the cut, the body’s reactions are reflexes, i.e. responses to influences from the environment or internal environment of the body, mediated through the central nervous system.

Biol. the importance of reflex mechanisms lies in regulating the work of organs and coordinating their functional interaction in order to ensure the constancy of the internal environment of the body (see Homeostasis), maintaining its integrity and the ability to adapt to changing environmental conditions. The reflex activity of the nervous system ensures the functional unity of individual body systems, as well as the complex, variable and adaptive nature of the body’s interaction with the environment (see Adaptation, Reflex, Self-regulation of physiological functions).

Methodologically, R. t. can be considered as a special case philosophical category reflection, understood as the property of material bodies to reproduce the features of objects interacting with them; R. t. generalizes materialistic ideas about the functions of the nervous system and the origin of the human psyche as the highest form of reflection (see Nervism, Nervous system, Psyche).

R. t. was created in the process of centuries-old searches for a solution to the problem of soul and body, mental and physiological.

R. Descartes is usually considered the founder of R. t., although already in the works of ancient scientists one can find the beginnings of ideas about the brain as a central regulator of body functions. The merit of R. Descartes is the creation of a general concept of reflex (reflected) activity of the nervous system. In his views on mechanisms, the so-called. involuntary movements, he proceeded from the teachings of W. Harvey on the movement of blood through vessels and the ideas of A. Vesalius, who believed that nerves perform the same function in relation to the brain as vessels do in relation to the heart. R. Descartes believed that external irritation releases the so-called in the nerves. animal spirits, which move to the brain, and from there to the muscles, changing their configuration and thereby causing their contraction. He emphasized that animal spirits have a material nature. Creating the theory of nervous activity, R. Descartes sought a compromise between the automaticity of reflex reactions and the complexity of real behavior, which determined the dualistic nature of the concept.

Having extended the idea of ​​causality to the study of the nature of motor acts, R. Descartes at the same time believed that the principle of reflex, introduced by him into physiology, can only be used to explain simpler (involuntary) reactions, i.e., manifestations of the sphere of life activity in which he Following Aristotle, he was assigned to physics. R. Descartes associated more complex voluntary reactions with the action of a higher immaterial substance, or soul, belonging to the sphere of metaphysics, existing only in humans and comprehended through introspection or reflection.

Starting from the second half of the 17th century. Significant contributions to the development of rheumatism were made by such naturalists as J. Swammerdam, T. Willis, J. Lamette, A. Haller, R. Whytt, I. Prohaska, and others. Objective physiol. concepts (“stimulus”, “excitability”, “sensory and motor nerve fibers”, “nerve centers”, “excitement”, “influence of the nerve”, “adequacy of the reaction to the stimulus”, etc.), which are also used by modern researchers have proven the reflex nature of the regulation of the activity of various organs (reaction of the pupil to light, contraction of the muscles of the inner ear to sound, etc.) and made an important conclusion that all acts, both voluntary and involuntary, are carried out using the same muscles, and the process of contraction itself is physiological. nature is the same for both. The factual material accumulated by this time made it possible to clarify physiol. features of the reflex act: a strict and constant relationship between the place of stimulation and the nature of the motor response, the adequacy of the response to the strength of the applied stimulus, the need for participation in the reflex process of a certain nerve center, in which the transition of excitation from the sensory nerve to the motor nerve occurs.

An important step in the development of radio technology was made at the beginning of the 19th century. C. Bell and F. Magendie. They found that the dorsal roots of the spinal cord consist of sensory, and the anterior roots of motor nerve fibers. Thus, speculative conclusions about the reflex pathway received a specific anatomical embodiment. C. Bell also put forward the idea of ​​the important role of feedback from the muscles to the brain for the precise regulation of movements, which laid the foundation for the idea of ​​chain reflexes (see Chain reflex). M. Flourens, based on experiments with the removal of the cerebellum and cerebral hemispheres of pigeons, came to the conclusion about the coordinating role of brain centers. Hall (M. Hall) was the first to use the term “nervous arch.” The works of M. Gall and I. Müller, as well as the scientific discussion between them, were of great importance for the development of R. t. Gall conducted subtle analytical studies of various reflexes. He developed a system of wedges, concepts based on the idea of ​​the existence of a three-term reflex arc(he also introduced this term), and used them to explain the mechanisms of paralysis, paresis and other disorders of the nervous system. I. Muller studied the integral mechanisms of the reflex. He pointed out that reflexes such as coughing, vomiting and sneezing are of a generalized nature, although they are often caused by strictly local irritations. He explained the coordination of reflex activity by the intervention of consciousness, associated with the brain and having a fundamentally different organization. I. Muller made a significant contribution to the study of the nature of sensations. On the issue of the role of sensations in reflex activity, a scientific controversy arose between Gall and I. Muller. Gall, in particular, believed that in reflex movements the excitation of the receptor is not accompanied by sensation, which he considered a sign of a volitional act that does not have reflex nature. I. Müller disputed this statement, arguing that involuntary generalized reflexes are naturally associated with sensation. Essentially, it was a dispute about the mechanisms of integrative manifestations of brain activity, the role of the psyche in the implementation of nervous acts, which received a new impetus in connection with the work of E. Pfluger, who showed that quite complex coordination of movements can be observed in a headless frog.

Despite great successes in the study of the nervous system, largely related to the development of the idea of ​​the reflex, until the mid-19th century. researchers could not approach the explanation of the most complex manifestations of nervous activity from the position of determinism (see). Research continued to be carried out within the framework of a subtle analysis of elementary reflex reactions, the explanation of the nature and laws of integrative nervous acts was carried out from the standpoint of mechanism or dualism.

The decisive step in the development of R. t. was made by I. M. Sechenov. For the first time in the history of science, I. M. Sechenov refused idealistic ideas his predecessors and provided systematic evidence that the brain, in its most complex manifestations, works on the principle of a reflex. Thus, the line that until then had separated seemingly completely different spheres - the physiological and mental spheres - was overcome. I.M. Sechenov’s discovery of the phenomena of central inhibition (1862) showed that a reflex act does not necessarily have to end in movement. In 1863, I.M. Sechenov published the book “Reflexes of the Brain”, in which he made the fundamental conclusion that “all acts of conscious and unconscious life, according to the method of origin, are reflexes,” i.e., he extended the reflex mechanism to area of ​​mental activity. I. M. Sechenov used a harmonious and consistent system of evidence. The main arguments of I.M. Sechenov are as follows. All manifestations mental life are caused directly or indirectly by external influences and are ultimately realized through movements, which makes them similar to reflexes. The complex temporal and force relationships between external stimulus, mental act and movement are explained by the presence of reflexes with a strengthened and delayed end. The main argument of his opponents, that the explanation of mental activity from the standpoint of a reflex is too much of a simplification, was refuted by I.M. Sechenov with the idea of ​​\u200b\u200bthe development of the psyche in the process of phylo- and ontogenesis. I.M. Sechenov showed that by observing the development of a child, one can trace how his undifferentiated reactions turn into ordered and highly specialized (including speech), and the immediate response is replaced by a delayed response or the child learns to suppress it. Thus, mental processes unfold in time and space, which unites mental processes with physiological ones.

Although the ideas of I.M. Sechenov attracted everyone's attention, strong objections were voiced against explaining the origin of the psyche from the standpoint of materialism. I.M. Sechenov entered into scientific polemics with his opponents with unsurpassed skill. His main idea was developed in the works “Who and How to Develop Psychology” (1873), “Elements of Thought” (1878) and DR.

At the end of the 19th - beginning of the 20th centuries. Two main directions in the study of brain activity have emerged: the continuation of work on the study of the mechanisms of nervous activity and the development of experimental psychology. Among the works of the first direction, the works of Charles Sherrington deserve the most attention. This researcher made a significant contribution to the study of the mechanisms of integration of motor reflexes, discovered the law of positive and negative induction, formulated the position of a common final path, showing that the idea of ​​an isolated reflex arc is to a certain extent an abstraction. The same period dates back to the beginning of the use of electrophysiological methods in the study of the nervous system, which subsequently played an important role in the study of brain function.

Work in the field of experimental psychology was aimed at studying physiology. correlates of the psyche. Despite the fact that a large amount of factual material was accumulated in these studies, the creation of a general concept encountered great difficulties, largely due to the dualistic approach to solving the problem of the origin of the psyche, within the framework of which physiological and mental phenomena were considered to occur in parallel and to a certain extent independently of each other (the so-called problem of psychophysical parallelism).

The development of brain science required the development of new approaches to the study of the mechanisms of higher nervous acts.

The decisive success in this direction is associated with the name of I. P. Pavlov, who fundamentally created new method physiological, experimental study of the most complex manifestations of brain activity, which until then belonged to the mental sphere - the method of conditioned reflexes. I.P. Pavlov’s teaching about the conditioned reflex (q.v.) was the basis of the materialistic concept he created about higher nervous activity (q.v.).

I.P. Pavlov believed that c. n. d. is based on a few vitally important innate unconditioned reflexes (see), which represent a genetically fixed and hereditarily transmitted experience of adaptive activity. However unconditioned reflexes able to ensure the organism's adaptation to environmental conditions only if the environment is absolutely constant. On the basis of unconditioned reflexes, conditioned reflexes, which are reflexes of a higher rank, can be developed throughout life. Conditioned reflexes are not predetermined by the innate structure of nerve connections, but are developed during the individual life of the organism in higher departments brain The development of a conditioned reflex represents a restructuring of the relationships between nerve centers, thanks to which these relationships begin to reflect the real interaction between environmental factors, which creates the opportunity for a more perfect adaptation of the body to this environment.

The body's response to an external stimulus is determined, according to I.P. Pavlov, by the interaction of the processes of excitation (see) and inhibition (see). In this case, internal inhibition, unlike external inhibition, can be developed in the process of interaction of the organism with the environment, which allows for extremely accurate and specialized reactions.

IP Pavlov put forward three principles of reflex activity, which were fully applied to conditioned reflexes: the principle of determinism, the principle of analysis and synthesis, and the principle of matching dynamics to structure. The last position (i.e., the relationship of dynamics to structure) gave rise to a scientific discussion between I. P. Pavlov, on the one hand, and I. R. Tarkhanov and V. M. Bekhterev, on the other. The latter argued that conditioned reflexes can rightfully be classified as physiological rather than mental phenomena, provided they are localized in certain areas of the cerebral cortex. The experiments carried out by I.P. Pavlov with the extirpation of individual sections of the cortex, as a result of which the connection of reflexes of various sensory modalities with certain cortical areas was established, showed the correctness of his views.

Research by I. P. Pavlov in the field of n. d. made a huge contribution to world science. A doctrine was created about the functions of the cerebral cortex (see), the basic laws of its work, physiol. basics of types of higher nervous activity (see), experimental neuroses, pharmacotherapy of nervous processes; An attempt was made to explain the pathogenesis of nervous and mental diseases from the standpoint of the doctrine of conditioned reflexes.

The further development of R. t. is associated with the teaching of I. P. Pavlov about the second signal system, which is inherent only to humans. The activity of the second signaling system, according to I.P. Pavlov, creates the possibility of abstraction and represents the basis for generalizing collective experience and communication between people. At the same time, it retains all the basic properties of reflex activity and obeys its laws.

Teachings of P.P. Pavlov essentially predetermined the direction of further research into the mechanisms of higher nervous acts.

V. M. Bekhterev made a significant contribution to the development of radiological technology. He did a lot in studying the conductive pathways of the spinal cord and brain, described a number of previously unknown brain structures, showed the connection of the motor fields of the cerebral cortex with acquired (learned) movements, established the anatomical and physiological foundations of balance and orientation in space, developed a technique combination motor reflexes, used by him and his students in the treatment of a number of neuropsychiatric diseases.

An important role in clarifying physiol. the mechanisms of nervous activity were played by the works of N. E. Vvedensky and A. A. Ukhtomsky. H. E. Vvedensky was one of the first to show the rhythmic nature of nervous excitation and introduced the concept of lability (see) to describe the functional mobility of the nervous system, which allowed him to genetically link the processes of excitation and inhibition and establish important patterns of interaction between nerve centers. A. A. Ukhtomsky developed the doctrine of the dominant (see) and developed the concept of the assimilation of rhythm as one of the universal principles of nervous system activity. The works of these scientists had a significant impact on the formation of electrophy-aiol. method for studying the mechanisms of brain activity. The works of E. Adrian, J. Eccles, B. Katz, A. Hodgkin, P. G. Kostyuk and others also made a great contribution. Intensive study of brain function using electrophysiol. methods led to the discovery of functional patterns that showed the complexity of the interaction of brain structures in the process of holistic activity.

The current stage of development of R. t. is characterized by the further creative development of the teachings of I. P. Pavlov about century. n. etc., an organic combination of the achievements of general physiology of the nervous system with the conditioned reflex theory. Based on the study of neurophysiol. mechanisms of integral forms of purposeful activity P.K. Anokhin put forward the concept of a functional system as the basis of the brain organization of a behavioral act (see Functional systems). The functional system is a complex reflex act, including a number of stages: afferent synthesis (see), decision-making, acceptor of action results (see), etc. Fundamental integral part system is the presence of reverse afferentation from the results of the action to the nerve centers that organize it, due to the cut, in the event of a discrepancy between the expected and the real result, a restructuring of the structure of the nervous act is organized.

E. A. Asratyan conducted detailed studies of the brain mechanisms of classical and instrumental (motor) conditioned reflexes, developed and substantiated the idea of ​​the existence of a special class of causal conditioned reflexes that reflect and record cause-and-effect relationships between external events, described and studied in detail the feedback connections between centers of unconditioned and conditioned reflexes, the idea of ​​a conditioned reflex as a synthesis of two or more unconditioned reflexes, etc. was expressed. The doctrine of v. n. etc. was also developed in the works of P. S. Kupalov, N. Yu. Belenkov, M. M. Khananashvili, A. S. Batuev. The mechanisms of complex behavior were studied by I. S. Beritashvili. Ideas about the elementary rational activity of animals were developed by JI. V. Krushinsky. To extend the reflex and conditioned reflex principle to the regulation of activity internal organs important had works by K. M. Bykov and V. N. Chernigovsky devoted to the study of interoception (see). I. P. Pavlov’s idea about the trophic innervation of tissues received further creative development in the works of JI. A. Orbeli, A. D. Speransky, as well as V. A. Govyrin, G. N. Krzhanovsky and Ya. I. Azhipa. It served as the basis for the creation of methods for reflex stimulation of restoration processes in the organs and tissues of the body.

Important studies of the mechanisms of conditioned reflex activity were carried out by M. N. Livanov. The electroencephaloscope he created made it possible to simultaneously record electrical activity in up to one hundred areas of the brain. It was shown that the formation and reproduction of conditioned reflexes is based on spatial synchronization of the electrical activity of the corresponding areas of the cortex and subcortical formations, reflecting the process of equalizing the lability of these structures.

The role of the dominant mechanism in the formation of conditioned reflex activity, as well as the significance of slow fluctuations in the electrical activity of the brain in the organization of brain processes are described by V. S. Rusinov.

Modern achievements in the field of studying the function of subcortical structures of the brain can be considered as confirmation and development of I. P. Pavlov’s concept of cortico-subcortical relationships. An important contribution to the system of knowledge about the brain was made by the discovery of the functions of the so-called. reticular formation of the brain. The works of X. Megun and J. Moruzzi show the presence in the brain stem of centers that regulate the tone of both underlying and overlying parts of the brain. These centers include the reticular formation of the medulla oblongata and midbrain, which, together with the various nuclei of the thalamus and hypothalamus, forms an ascending activating system (see Reticular formation). This system is also called the nonspecific system of ascending projections. The nonspecific system receives impulses from fibers of various modalities, has a relatively diffuse projection in the cerebral cortex and largely determines its tone. Later it was shown that, in turn, the tone of the reticular formation is regulated by descending cortical influences.

Structural and functional features of brain activity are described by O. S. Adrianov. In particular, he studied brain projections in the primary and associative cortical zones, as well as nerve pathways connecting sections of the neocortex and limbic cortex with subcortical formations.

I. P. Pavlov’s idea of ​​reinforcement as a decisive factor in the formation of a conditioned reflex was confirmed by the discovery by Olds and Milner (J. Olds, P. Milner) of the so-called. reinforcing brain structures (see Self-irritation). It has been established that direct electrical stimulation of these brain formations, causing positive and negative emotional states, can serve as the basis for the development of conditioned reflexes.

A great contribution to the study of the neurophysiological mechanisms of emotions (see) and their role in reinforcing conditioned reflex activity was made by P. V. Simonov. Developing the idea of ​​I. P. Pavlov about a dynamic stereotype, P. V. Simonov created an information theory of emotions, in accordance with the cut of the sign and degree emotional stress determined by the strength of the need and the likelihood of its satisfaction. This probability, in turn, is determined by the difference between the information predicted to be necessary to satisfy the need and the information actually available to the subject. Important studies of the neurochemical foundations of brain activity were carried out by E. M. Kreps, H. Hyden, A. V. Valdman, R. I. Kruglikov, R. Yu. Ilyuchenko, I. P. Anokhina.

Physiol. mechanisms of motivation (see), as well as the role of emotional stress (see) in the pathogenesis of psychosomatic diseases have been studied in detail by K. V. Sudakov. Theory functional system P.K. Anokhin, as well as the principle of “quantization” of the body’s reactions, proposed by K.V. Sudakov, were applied by him to study physiol. reactions in the process of human production activity.

Research in. n. d. people confirmed, supplemented and expanded I. P. Pavlov’s ideas about the second signaling system (works of A. G. Ivanov-Smolensky, I. V. Strelchuk, M. M. Koltsova). Data on the physiology of the human brain have demonstrated the complexity of the localization of functions and the multiplicity of structures at different levels of the brain involved in ensuring its activity.

IP Pavlov considered the ultimate goal of his teaching to be knowledge of physiology. mechanisms of the psyche. He saw the path to solving this problem in the consistent study of objective manifestations and laws of brain activity. At the same time, I.P. Pavlov did not deny the uniqueness of the mental sphere as the highest form of manifestation of brain activity and the need scientific analysis subjective experiences. I. P. Pavlov said that science will transfer the obtained objective data, guided by the similarity or identity of external manifestations, sooner or later to our subjective world and thereby immediately and brightly illuminate our so mysterious nature, understand the mechanism and vital meaning of what what occupies a person more and more is his consciousness, the torment of his consciousness (I. P. Pavlov. Complete collected works, vol. III, book 1, 1951, p. 39).

The successes of physiology in recent decades, its progress along the path paved by I. P. Pavlov, have made it possible to pose the problem of studying the physiological foundations of mental activity. The problem of the relationship between the brain and the psyche is of considerable complexity; it has not only natural scientific, but also philosophical significance. Fundamental for understanding the nature of mental activity is the position of dialectical materialism about the reflective nature of the psyche, that mental activity, being a product of the brain, reflects not the brain processes themselves, but through the mediation of brain processes the external world, objective reality. At the same time, mental reflection is not a passive process, it is active. According to V.I. Lenin, “human consciousness not only reflects the objective world, but also creates it” (V.I. Lenin. Complete collection of works, vol. 29, p. 194). Ideas about the reflective nature of the psyche and its active, “creative” influence on the world directly connect the mental sphere with the principles of reflex and the basic ideas of R. t.

For a targeted study of the mechanisms of the psyche, it is necessary to know what is the qualitative difference between mental processes and simpler manifestations of brain activity. This difference is largely due to the phenomenon of human consciousness. Consciousness (see) is the highest form of reflection, in which the external world is perceived as something separate from the subject. Consciousness is closely related to speech (see) and arises in the process of communication between people.

Physiol. psychophysiology studies the mechanisms of the psyche. I.M. Sechenov and I.P. Pavlov can rightfully be considered the founders of this section of physiology, who created its theoretical basis and indicated ways to solve the problems facing it based on the development of the idea of ​​​​the reflex. Modern psychophysiology has a wide arsenal of methodological techniques. Along with the method of conditioned reflexes, recording of the electrical activity of the brain is widely used, including the method of evoked potentials and recording the activity of nerve cells, the study of cerebral blood flow, neurochemical changes, etc. Methods of modern psychology and psychophysics are also used, which make it possible to quantitatively assess the state of certain mental processes. Analysis of the obtained data is usually carried out using a computer.

Psychophysiology is also of great importance for solving a number of problems of interaction between man and technology, and human work in extreme conditions. It is also important for understanding the nature of mental illnesses, developing measures for their diagnosis and treatment. P.K. Anokhin, M.N. Livanov, V.S. Rusinov, N.P. Bekhtereva, R.A. Luria, A.M. Ivanitsky, E.N. Sokolov, E. A. Kostandov, K.K. Monakhov, etc. Abroad, significant contributions to this area of ​​science were made by W. Penfield, G. Jasper, W. Walter, K. Pribram, and others.

The study of hemispheric specialization and interhemispheric interaction was important for understanding the brain processes underlying mental activity. Sperry (R. W. Sperry) and Gazzaniga (M. Gazzaniga) examined brain functions in individuals who had undergone surgery to cut the corpus callosum for the treatment of epilepsy. Such patients were presented with an image of an object separately for the right and left eyes (the image was sent to the left or right hemisphere of the brain, respectively). Regardless of which eye the patient saw the image with, he could then select this object by touch from a number of others. However, if the image entered the right hemisphere, the person could not name the object and explain why he chose it. When information entered the left hemisphere, the subject could give a full verbal report of his actions. Further research has shown that the specialization of the hemispheres is also manifested in the fact that the left hemisphere is predominantly associated with abstract thinking and verbal-logical operations, and the right hemisphere with intuitive thinking, analysis of the shape of objects and spatial orientation. Mental activity is the result of coordinated work of both hemispheres.

Great contribution to the study of the morphofunctional organization of physiol. ensuring human mental activity was introduced by N. P. Bekhtereva et al. Their studies used diagnostic and therapeutic techniques for stimulating the human brain using chronically implanted electrodes, as well as analyzing the bioelectrical brain activity generated by these electrodes. New data were obtained on the role of subcortical structures of the human brain in various emotional reactions, memory phenomena, as well as on the principles of encoding semantic information in the impulse activity of neurons. Based on the research carried out, an important thesis was put forward about the provision of mental function by a system of links with varying degrees of rigidity. The rigid links of the system are a necessary element to ensure this mental function, while the flexible links are connected to the system only under certain conditions. The latter structures are also characterized by polyvalence and can take part in providing various mental functions.

With the improvement of stereotactic technique, allowing local electrical stimulation various entities human brain in a wedge, practice, new ways of treating various pathol have been outlined. processes. Thus, as a result of point electrical stimulation, it was possible to relieve phantom pain syndrome in patients, cause an improvement in the health status of patients with hyperkinesis, and relieve acute and chronic phobias.

Ideas about the very complex and multi-level nature of the brain processes that ensure mental activity, about the psyche as a result of brain integration, were also confirmed in the study of physiol. mechanisms of perception. In the studies of A. M. Ivanitsky, it was shown that perception (see) as a mental function is much more difficult process than the simple arrival of nerve impulses from receptors to the projection cortex. The construction of a subjective image is associated with the synthesis of all information about the stimulus, both coming from the senses and stored in memory. Activation of memory traces (see) occurs through the mechanism of a conditioned reflex. Based on past experience, the significance of the current stimulus is determined. Information about the significance of the stimulus then returns to the site of the primary projection of the stimulus, where it merges with traces of sensory excitation. This moment corresponds to the occurrence of sensation. Perception is based, therefore, on the complex interaction of the projection and associative cortex, as well as subcortical centers of emotions and motivations. Psychic reflection occurs at the junction of external and internal, present stimulus and memory. The idea of ​​the psyche as cerebral integration is also important for understanding the nature of mental illnesses, the pathogenesis of which, as studies have shown, is largely associated with disruption of the interaction between individual links of the system that provides mental function.

Summarizing modern ideas about the nature of the psyche, we can say that the difference between simpler reactions and reactions at the psychological level lies in the fact that in the first case only minimum required brain structures, and in the second, almost the entire brain is involved in processing incoming information, which is ensured by the complex interaction of its most important parts and the special organization of information flows in the brain. However, in both cases, the principle of reflex, i.e., reflected action, remains unchanged. Complication occurs ch. arr. in the central link of the reflex. Factors such as memory, emotion and personal motives are becoming increasingly important. This allows the body to build complex behavior, which is formed on the basis of all past experience, both individual and collective.

It should also be emphasized that in these perfect functions the reflex retains its significance not only as general principle integral reaction of the body, but also as an elementary unit of nervous action, on the synthesis of which any, even the most complex, behavior is based. The dialectical law of the transition from quantity to quality is fully manifested in the evolution of brain functions. Based on the increase in the number and complexity of the organization of elementary units, qualitative shifts occur, expressing themselves in more complex forms of reflecting reality and ensuring more perfect behavior.

R. t., summarizing modern ideas about the work of the brain, is the leading concept in the physiology of the nervous system. It is closely related to the materialistic understanding of the inextricable connection of the organism with the environment, on the one hand, and the active, creative influence of the organism on this environment, on the other. This determines the significance of R. t. as one of the fundamental theoretical generalizations modern biology and medicine.

Bibliography: Lenin V.I. Materialism and empirio-criticism, Complete. collection soch., 5th ed., vol. 18, M., 1968; Adrianov O. S. On the principles of organizing integrative brain activity, M., 1976, bibliogr.; Anokhin P.K. Biology and neurophysiology of the conditioned reflex, M., 1968, bibliogr.; aka, Selected works, Systemic mechanisms of higher nervous activity, M., 1979; Asratyan E. A. Essays on higher nervous activity, Yerevan, 1977; Bekhtereva N.P. Neurophysiological aspects of human mental activity, L., 1974, bibliogr.; aka, Healthy and sick human brain, L., 1980, bibliogr.; Vvedensky N. E. Excitation, inhibition and anesthesia, St. Petersburg, 1901; Ivanitsky A. M. Brain mechanisms for assessing signals, M., 1976, bibliogr.; K o s t yu k P. G. Structure and function of descending systems of the spinal cord, L., 1973; Livanov M. N. Spatial organization of brain processes, M., 1972, bibliogr.; Mechanisms of formation and inhibition of conditioned reflexes, ed. V. S. Rusinova et al., M., 1973; Pavlov I.P. Twenty years of experience in the objective study of higher nervous activity (behavior) of animals, M., 1973; Rusinov V. S. Dominanta, M., 1969; Sechenov I.M. Selected works, vol. 1, p. 7, M., 1952; Simonov P.V. Higher nervous activity of a person, Motivational and emotional aspects, M., 1975, bibliogr.; aka, Emotional Brain, M., 1981, bibliogr.; Sudakov K.V. Systemic mechanisms of emotional stress, M., 1981, bibliogr.; Ukhtomsky A. A. Dominant, M.-L., 1966, bibliogr.; Chernigovsky V. N. Intero-ceptors, M., 1960, bibliogr.; Sherry ng ton Ch. Integrative activity of the nervous system, trans. from English, Leningrad, 1969; E k l s J. Physiology of nerve cells, trans. from English, M., 1959; G a z-z a n i g a M. S. a. L e D o u x J. E. The integrated mind, N. Y. - L., 1978; M o r u z z i G. a. Magoun H. W. Brain stem reticular formation and activation of EEG, Electroenceph. clin. Neurophysiol., v. 1, p. 455, 1949; SperryR.W. A modified concept of consciousness, Psychol. Rev., v. 76, p. 532, 1969.

REFLECTOR THEORY OF BEHAVIOR. Reflex is the main form of activity of the nervous system. The simplest reflexes belong to the innate, or unconditioned; they are inherited and ensure the body's adaptation to constant environmental conditions. Unconditioned reflexes refer to specific characteristics of animal behavior. Already in a newborn child, the simplest unconditioned reactions are observed: sucking (food unconditioned reflex), blinking of the eyes (protective unconditioned reflex), reflex, “what is it?” (approximate unconditioned reflex).

More complex forms of innate behavior are called instincts.

In the conditions of the external world, which is constantly changing, in addition to unconditioned reflexes, each individual organism has its own, individual experience. The same unconditioned reflexes can be performed both in response to hereditarily given stimuli and to those signals that a given organism encounters only in its individual life. Such reflexes are called conditioned.

Conditioned reflexes are reactions acquired during the life of each person, with the help of which the body adapts to the changing influences of the environment. Conditioned reflexes are not inherited, but are acquired during the learning process. A conditioned reflex is formed when some external event coincides in time with one or another activity of the body or is reinforced by an unconditioned reflex.

Throughout life, many complex conditioned reflexes are produced that become part of our life experience. Motor conditioned reflexes that are produced by a person throughout life are called skills, or automated actions, with the help of which a person masters new motor skills and produces new forms of behavior.

Consequently, our behavior is determined by: 1) internal needs and 2) specific external conditions to which we constantly adapt with the help of unconditioned and conditioned reflexes. Consequently, our behavior is not only active and purposeful, but also subtly and precisely adapted to environmental conditions.

ADAPTIVE BEHAVIOR. For the normal existence of an organism in a changeable external environment, it is necessary to change its behavior in time and adapt to specific conditions.

The ability to manage one’s behavior, change it in time, and sometimes completely restrain one or another behavioral reaction is one of the “important features of a well-mannered person.

A distinction is made between unconditioned inhibition (when an unconditioned orienting reflex inhibits the corresponding behavior) and conditioned inhibition (when a gradual extinction of the conditioned reflex occurs as a result of its not being reinforced by an unconditioned stimulus). Those conditioned reflexes and skills that cease to be vitally important for a person or are not reinforced fade away. Instead, during the learning process, other forms of behavior are produced (conditioned reflexes), which better adapt the human body to environmental conditions.