Higher nervous activity of a person. Higher nervous activity. "Unconditioned reflexes"

HIGHER NERVOUS PERFORMANCE

Life at every step shows the immeasurable superiority of the mind of people over the primitive thinking abilities of animals. The huge gap between the mental life of man and animals has long served as a reason for attempts to present human consciousness as a supernatural phenomenon, inaccessible to objective study. However, the advances in psychology and physiology of higher nervous activity provide more and more opportunities for a natural-scientific explanation of the work of the brain of a thinking person.

The higher nervous activity of man included many achievements in the biological evolution of conditioned reflexes in animals and, in addition, acquired a system of completely new, purely human psychological activity, operating with abstract concepts expressed by speech and forming more and more complex verbal conditioned connections. The spoken word, and then the written word, united people in joint work, helped to accumulate knowledge and reach that high level of culture on which modern man stands.

Biological prerequisites for the emergence and development of higher functions of the human brain

The study of the natural history of the origin of man from the animal kingdom deprives the soil of mystical speculations about his "divine creation." An outstanding victory of science in this dispute was Charles Darwin's book "The Descent of Man" (1871), bold for that time. He has accumulated and systematized numerous convincing facts showing the genetic commonality of the structure of bodies and functions of human organs and his anthropoid ancestors.

What in the life of anthropoids turned their evolution in this direction? The way of life in trees, apparently, was largely due to the development of limbs capable of grasping branches and fruits with the help of fingers, which felt the objects encountered. This allowed the monkeys to manipulate them based on their needs. When, during the retreat of the forests, they descended to the ground, they could no longer return to the four-legged mode of movement. Only the hind limbs, having become supporting ones, underwent some reverse development and turned into legs, while the front ones improved their manipulative functions even more intensively. The "four-armed" monkey has become the bipedal ancestor of man with arms. The emergence and development of the hand was the most important biological prerequisite for the development of higher brain functions. "This was a decisive step in the transition from monkey to man."

Hand actions ushered in new forms of effective adaptive behavior that used broken branches, stones, and a variety of objects to forage for food and fight enemies. The tasks of controlling the complex, precisely coordinated movements of many muscles that carried out the actions of the hands caused an extraordinary development of the brain structures responsible for motor functions. The signals about this activity and the information obtained in the study of objects that fell into the hands were so important that the structures of the corresponding sensory kinesthetic functions, as well as the associative functions that organize behavior, formed on their basis, were also predominantly developed.

The herd lifestyle of individuals who have learned to operate with their hands has become another important biological prerequisite for the development of higher brain functions. On the basis of the high perfection of sensorimotor coordination when manipulating objects that have fallen into the hands and the formation of multiple forward and backward connections during the interaction of individuals, complex forms of analytic-synthetic brain activity have arisen. Imitative reflexes, which are enhanced by upbringing and condition the emergence of conditions for the development of various types of joint activity, have acquired particular importance. This was facilitated by the properties of the higher nervous activity of anthropoids described in detail in the previous chapter - the speed of formation of conditioned connections, the subtlety of differentiations, the ease of developing adequate responses to traces and signal complexes, solving complex behavioral problems, etc. The development of research and associative activity and the ability to form a rich fund of memory that determines behavior in different situations has acquired particular importance.

The change in the appearance of the anthropoid that rose to its feet especially affected the shape of its head and the size of the cerebral section of the skull. The extreme complication, mainly of sensorimotor mechanisms, led to the rapid development of the anterior parts of the brain and the proliferation of its frontal lobes, which changed the shape of the skull and caused it to protrude above the orbits. In primitive people, the face has already acquired the features characteristic of modern man.

Conditioned reflexes of the child

The development of the physiological activity of the child's brain reflects the history of the formation of human thought. The infant's behavior at first appears to consist of the usual feeding, defensive, and other animal reflexes. However, already at this time in the child, one can find the rudiments of a specially human system of nervous activity, which later manifests itself in speech.

Conditioned reflexes in a newborn baby. A large number of experiments were carried out to clarify the question of when the child's brain acquires the ability to form conditioned reflexes. Attempts to develop conditioned reflexes in an unborn fetus have led to conflicting results.

In experiments with premature babies born at 1–2 months ahead of time, it was possible to develop defensive conditioned reflexes of closing their eyes to the metronomic signal, accompanied by blowing over the face (N.I. Kasatkin, 1948). These reflexes were developed during the second month of postnatal life. However, the state of the higher nervous activity of premature babies largely depends on the timing of prematurity, the conditions of intrauterine development, and a number of other reasons. Special studies have shown that the ability to develop conditioned reflexes in premature babies is in a certain ratio with the degree of development of an orienting reflex in them and the formation of its behavioral and autonomic components. Visual food conditioned reflexes in premature babies 1–1.5 months are formed by the 22–39th day of postnatal life, and in premature babies 3 months - by the 59–75th day.

Attempts to develop food and defense conditioned reflexes in newborns in the first days of life also led to contradictory results, which, apparently, reflects the uneven maturation of the nervous mechanisms of the cerebral hemispheres of the human brain. Only from about one week of age, the child's ability to form conditioned reflexes becomes undoubted. By this time, the first natural conditioned reflexes can also be observed in him.

Development of early conditioned reflexes in children. Some mothers claim that the baby recognizes them as early as one or two weeks old, reaches out and sucks when they pick him up. However, in reality, the child does not yet differentiate the people around him. Whoever picks him up in his normal feeding position, the baby will respond with the same motor response. The fact is that a baby at about one week of age develops a natural conditioned food reflex to the feeding position. The signal here is a complex of mainly skin and proprioceptive stimuli, reinforcement - feeding (VM Bekhterev, NM Shchelovanov, 1925).

Perhaps, even earlier, a natural conditioned reflex is formed at the time of feeding. So, with the exact observance of the correct intervals between feedings, already in five-day-old babies, it is possible to observe the awakening and the appearance of sucking movements a few minutes before each feeding period. According to other observations, if a constant feeding time is observed, then already in 8-9-day-old children there is an increase in the number of leukocytes in the blood before each feeding; development of a conditioned reaction of digestive leukocytosis.

Already during the first month of life, children can develop a variety of artificial conditioned reflexes. So, if before each feeding of 2-3-week-old babies, 15 seconds before giving the breast, sound or light signals are turned on, then after a few days, turning on only one signal can cause sucking movements. The age at which a particular reflex was formed depended on the type of signal stimulation applied.

Reflexes formed at an early age are specialized depending on specific life circumstances, complicating and clarifying the child's behavior. For example, the sight of the mother becomes a habitual signal of feeding, and the white coat of a painful doctor triggers a violent defense reaction. The child reaches for a bottle of milk and, crying, turns away from the spoon, in which he receives the bitter medicine.

Development of inhibition of early conditioned reflexes in children. It takes a long time for the child to really begin to recognize his mother. Only at the age of 3-4 months is he able to clearly differentiate the stimuli of the complex signal of receiving food. By this time, the reaction to the cutaneous and proprioceptive members of the signaling complex will fade away, and the food reflex specializes in its visual component.

A clear differentiation of artificial visual and auditory conditioned stimuli also occurs at 3-4 months of age. Prior to this, attempts to develop differentiations lead to very vague results. Lag inhibition was developed only when the children were 5 months old, and then with great difficulty.

Thus, the child's brain reveals the first signs of the ability to develop different types of internal inhibition in approximately the following terms: differentiation - at 1.5–2 months, extinguishing - at 2–2.5 months, to develop a conditioned brake - at 2.5–2.5 months. 3 months and lag inhibition - in 5 months.

Everyday life gives many examples of the specialization and refinement of the child's natural conditioned reflexes by means of various types of internal inhibition. The simplest case is the development of differentiation of visual stimuli with the specialization of the conditioned food reflex to the appearance of the mother. The development of a conditional brake turns out to be more difficult.

For example, when the porridge cooked for a child is still hot, the mother first blows on it, and then scoops up and feeds the child. In the first days of feeding, the child, seeing a saucer of porridge (a positive food stimulus), immediately opens his mouth and continuously reaches for the saucer. But after a few days, it is enough for the mother to blow on the saucer (an additional agent) for the food reaction to temporarily stop (conditioned inhibition).

The combination of forms of inhibitory refinement of the reflex becomes more and more complex and varied with age.

Motor conditioned reflexes of the child. For the study of motor conditioned reflexes in children, special techniques have been developed (A.G. Ivanov-Smolensky, 1933). The most widely used was the development of conditioned reflexes for grasping an object with the hand or for performing a given movement. Such participation of the hand in the conditioned reflex is associated with the activity of complex mechanisms of the brain, the work of which psychology defines as arbitrary or volitional actions. They fall into various categories of adult actions. In fig. 101 shows a setup for developing simple conditioned grasping reflexes with food reinforcement.

Rice. 101. Installation for the study of conditioned grasping reflexes in children (according to A. Ivanov-Smolensky):

1 - signal bell, 2 - tube for feeding food reinforcement (candy), 3 - glazed part of the tube, 4 - the upper gate opened by the experimenter, 5 - the lower gate opened by the subject, 6 - recording of the conditioned reflex movement of grasping and squeezing a rubber bulb, 7 and 8 - marks of conditioned stimulus and food reinforcement

The child is first taught to use the apparatus. For this, the experimenter opens the upper pneumatic shutter of the inclined tube with the help of a pear, along which the candy begins to slide. When the candy enters the field of vision of the subject, the latter, seeing it through the glazed part of the tube, must grab the rubber bulb and open the lower gate. Then the candy will fall out on the saucer, from where the child can take and eat it.

After such a conditioned reflex of opening the shutter is developed to obtain a candy, it is used as a reinforcing reflex for the formation of conditioned reflexes to visual, auditory and any other signals.

Another peculiar form of the child's motor conditioned reflexes are those that are developed on reinforcement by orientational-research reactions. Orientation reflexes are very pronounced in children. If, for example, you turn on the bell and then show moving pictures on the side screen, then soon, just after hearing the bell, the child turns to the side of the screen.

The study of motor reflexes has shown that these more mobile manifestations of the child's mental activity are subject to the general laws of the development of excitation and inhibition, movement and induction of nervous processes, according to which the higher parts of the brain work. In these reflexes, even more than in salivary ones, there is an extraordinary progress in the development of even the general properties of nervous processes in children in comparison with the most highly developed animals, and the presence of such forms of higher nervous activity that do not occur at all in animals.

For example, the experimenter has formed a conditioned grasping reflex in the child and wants to develop the differentiation of signal tones. He turns on an unsupported tone, and the child, instead of moving his hand, reacts with the words: "Uncle, do not buzz badly, give me some candy." Having failed to reach the goal with the biological grasping reflex, the child turned to a purely human signaling device - the word.

Mastering speech is a turning point in a child's life. Thus, although the motor conditioned reflexes of children are carried out according to the general laws of higher nervous activity, one can also find in them such manifestations that constitute an exceptional feature of a person, primarily speech reactions.

The second signaling system of the human brain

While the child's brain carried out even very complex food, defensive, orienting and other conditioned reflexes, its work did not yet go beyond the boundaries of the general laws of adaptive biological activity common with animals. But very soon this form of behavior is obscured by the manifestations of a fundamentally new reflex mechanism, characteristic only of a person, which finds its fullest expression in oral and written speech.

Human "increase" in nervous activity. The fundamental feature of the mental activity of the human brain, which distinguishes it from all animals, is the presence of consciousness in a person. Human consciousness is characterized by the formation of generalized and abstract complexes of conditioned stimuli - concepts expressed in words.

Human consciousness arose as a result of the fact that the biological struggle for existence and the "consumer" form of animal behavior were replaced by the social way of life and the creative labor activity of people. Therefore, the psychic perception of natural stimuli by animals as the sum of direct food, defensive, etc. signals have been replaced in humans by a holistic perception of the world around them in terms created by history and the needs of human society. Therefore, such a sharp border has been laid between the exclusively objective, concrete thinking of animals and the always abstractive, idea-creating consciousness of man.

Thanks to consciousness, a person can in his mind compare, try, come to new conclusions and, having drawn up a certain plan, be guided by it in actions. Animals are not capable of premeditated activities according to a plan. Although “the bee, by building its wax cells, puts some people-architects to shame. But even the worst architect differs from the best bee from the very beginning in that, before building a cell of wax, he has already built it in his head. "

Human consciousness is most clearly manifested in speech. Speech arose as a means of communication between people who, during joint work, “appeared need to say something each other". With words, people express thoughts, convey knowledge, and encourage one or another to take action. A person thinks in words, without even saying them. It is impossible to imagine the mental life of a person without the use of speech - oral, written, mental. No animal is able to exchange thoughts through conversation, this is a purely human ability.

So, the higher nervous activity of animals is exhausted by conditioned reflexes to specific signals of food, danger, etc., in the higher nervous activity of man, in addition, conditioned reflexes appear to generalizing concepts expressed in words. The first category of reflexes is biological in nature, the second is social.

There are various assumptions about the origin of the verbal conditioned reflexes that distinguish humans from animals. Previously, it was believed that they are formed by "stringing" a signal into a signal like conditioned reflexes of the second, third, fourth, etc. order. It was believed that this is how conditional chains of bonds arise, which lengthen more and more with age.

It was assumed, for example, that a small child first forms a simple conditioned reflex - connects the type of food with food. Then he begins to speak and associates words with the food that denote its name. Then he learns from adults that groceries need to be bought, and associates the concept of earnings with them.

Many concepts and motivations of a person were explained as developing from a natural food conditioned reflex. Other chains of connections, according to this view, appear on the basis of protective reflexes. For example, a prohibition, backed up by punishment in childhood, forms the concept of "no" and the associated norms of human behavior.

However, such an idea, like all others that connect the emergence of verbal reflexes with biological factors, contradicts what is known about the nature of speech: obviously, speech arose not from animal instincts, but as a result of joint labor of people. That is why a person's consciousness, his thoughts and behavior are determined not by fear and hunger, but by the interests of human society.

Based on all the above considerations, I.P. Pavlov divided the conditioned reflexes of a person into two fundamentally different categories. Conditioned reflexes to specific signals constitute the first signaling system of brain activity, common for humans and animals, and verbal conditioned reflexes form the second signaling system of brain activity, peculiar only to people.

The difference in the properties of the activity of the first and second signaling systems. The characteristic features of the conditioned reflex mechanism of the first signal system are: 1) the concreteness of the signal (this or that phenomenon of the surrounding reality), 2) the unconditioned basis of reinforcement (nutritional, protective or sexual value), 3) the biological nature of the adaptation achieved (to the best nutrition, defense, reproduction). The same specific traits are also characteristic of the child's first signaling system.

Conditioned reflexes of the second signal system arise on the basis of a different physiological mechanism, different driving forces with the involvement of conceptual and moral categories. For example, hearing cries for help, a person rescues a drowning man. The verbal signal given by the drowning person caused complex second-signal conditioned reflexes in his savior. What are the characteristic features of the reflexes of the second signaling system?

1. In contrast to the concreteness of the signal in the reflexes of the first signaling system, the word is an abstract signal. It acts not by its sound, but by the concept contained in it. A drowning man could call for help in different words... They sounded differently, but the thought contained in them reached everyone who heard the call.

The fact that the word acts not by its sound shell, but by its inner content, has been convincingly proved by experiments with synonymous words. For example, if you develop a conditioned reflex in a person to withdraw his hand to the word “fire,” then we can say “flame,” and the subject will withdraw his hand. It is clear that it is not about sounds, but about the meaning of words. Nothing of the kind can be obtained in experiments with animals. There, the signal is a specific sound once and for all.

The word as an abstract stimulus causes the conditioned excitation of not one analytic point, but their complex complex with the participation of many analyzers.

2. While the reinforcements in the first signaling system are food, defense, sexual reflexes, in the reflexes of the second signaling system, concepts expressed in words are reinforced by what a person sees, hears, does himself and discusses with other people. Only in this way could a connection be formed between the call for help and immediate actions to save the drowning person, with actions that not only do not provide a direct biological benefit to the rescuer, but are even associated with a risk to his life. It is not for nothing that such moral actions are called real human ones.

3. Finally, while the conditioned reflexes of the first signaling system provide direct satisfaction of the biological needs of the individual, conscious human activity is aimed at ensuring the vital needs of each person through the benefit of people and all of humanity. Therefore, in the conscious actions of a person, first of all, the motives of social duty and mutual assistance appear.

For all the properties of activity, the driving forces of its formation and development, the second signaling system is fundamentally new. Signaling with the help of a word has opened up the possibilities of progress inaccessible to animals. The word allowed each person to use the life experience of all mankind and, at the same time, to make every achievement of his own, to accumulate and multiply knowledge, to pass it on in the form of ready-made concepts to the younger generations. Writing has further expanded the possibilities of the word, facilitated the continuity of culture and helped humanity reach the modern heights of science, technology, art and social relations.

Formation of the word as a "signal of signals". Important information about the formation of a verbal stimulus as a synthetic "signal of signals" can be obtained from the study of the process of mastering speech by a child. Speech function is not innate, it is acquired through learning when a child communicates with speaking people.

Cases are described when babies, carried away by wild animals, remained alive and grew up, for example, in a wolf pack. Such children, when found, were wordless, they did not understand those around them, their second signaling system did not function.

Learning to speak begins with the fact that, usually in the second half of the first year of life, a child begins to develop various reactions to complex stimuli, of which the word is a member. For example, a child is told: "make goodies", take his handles, make the appropriate movement, while others clap their hands at the same time. Similarly, the child is taught to the question: "where is mom?" or "where is daddy?" look back at the mother or father, at the words "show your eyes" or "show your ears" indicate the named parts of the body, etc. Initially, the role of the word in such signaling complexes is comparatively insignificant. The determining members of the complex are statokinetic components (position of the child), visual (environment, people around), sound (intonation, timbre of the voice). This is clearly seen from the observations, the results of which are presented in table. eighteen.

Table 18. The value of various members of the complex stimulus for the reaction of an 8-month-old child (according to MM Koltsova)

When all the statokinetic, visual and sound members of the complex stimulus are present, which became the signal of movement towards the father, the reaction occurs. But if at least one of them falls out, there is no reaction. As you can see from the table. 18, this happens if you change the position of the child (put him in the crib), the environment (move from the bedroom to the dining room) or the intonation of the voice (angry tone). The verbal member of the complex in these cases is not able to provide its irritating effect.

However, further practice of verbal designation of the reaction gradually increases the role of the word among other members of the complex stimulus, the meaning of which gradually decreases. So, already 2 weeks after the experience presented in the table, the child correctly reacted to the question: where is dad? not only being in the arms of the mother, but also lying in the crib. After some time, the setting loses its meaning, the reaction occurs not only in the bedroom, but also in the dining room, and even on the street. Finally, by about the end of the first year, the final "liberation" of the word from other components of the complex occurs, and it begins to act as the main stimulus replacing the entire complex. From a pedagogical point of view, it is important to note that the speed of the process of the formation of the word as an independent and leading stimulus is extremely dependent on the conditions of upbringing, especially on the duration and frequency of conversational communication with adults.

A possible physiological mechanism for such a release of a verbal stimulus is the training of the strength and concentration of the nervous processes caused by them with negative induction on other members of the complex, which is facilitated by the constancy of the verbal component with endless variations of all other components in various situations of the child's life. Remaining a natural exponent of a whole complex of phenomena, the word carries out a certain degree of generalization and begins to turn from a simple sound stimulus into a speech signal.

The completion of such a transformation is determined by the accumulation a large number conditional connections that are consistently formed with a given word in a child, in particular during play and orientational activities.

In the formation of these connections, activity of the motor analyzer. So, the generalizing properties of a verbal stimulus turn out to be more pronounced and persistent when formed on given word a certain number of conditioned connections from the motor analyzer than with the formation of the same number of conditioned connections from the visual analyzer. Hence the great role of different forms motor, in particular game and orientational, activity. In turn, the word organizes the child's motor activity.

The role of the motor analyzer increases to an extraordinary degree when the child begins to speak himself. Each spoken word receives its expression in a certain combination of kinetic signals from the phonation apparatus, which have the same constancy that distinguished the word heard among all other members of the complex stimulus. At an older age, mastery of writing adds stereotypes of kinetic cues from the movements of the writing hand and visual cues from reading. It is the synthesis of all these signals that leads to the formation of a word - a concept, a “signal of signals”, a working mechanism of the activity of the second signaling system of the human brain.

Basic properties of reflexes of the second signaling system. The features of the conditioned reflexes of the second signal system are clearly seen in comparison with the reflexes of the first signal system, which have reached high perfection in humans. Their study, especially with verbal instructions, reveals the joint activity of these systems.

For special studies of the properties of second-signal activity, methods were developed involving the use of verbal stimuli (A.G. Ivanov-Smolensky, 1934). Of these, the most widely used was the method of developing conditioned reflexes based on speech reinforcement. For example, the experimenter gives the subject a rubber balloon connected to a pressure gauge, turns on the signal (bell, light bulb) and tells him to "press the balloon." When a connection is formed between the signal and the word, the subject performs this movement without waiting for an order. Along with the described, other conditioned reflexes of performing various movements in response to light, sound and speech signals are used without warning or with preliminary verbal instruction. Protective blinking, food swallowing and various vegetative salivary, cardiovascular, sweating, photochemical and other reflexes are also used. Their technique is described in detail in a special manual (S.M. Galperin, A.E. Tatarsky, 1973).

When studying the reflexes of the second signaling system, the following most characteristic properties appeared.

1. Continuous synthesis, expanding the content of verbal signals (the excitation of the analyzer complex, expressing a certain concept, continuously radiates). It extends the signaling meaning of this concept to all adjacent, i.e. generalizes these concepts more and more, distracting more and more from specific details.

This generalization was clearly evident in the following experiment. The student had a positive conditioned salivary reflex to the word “good” with differentiation of the word “bad”. After that, phrases containing the word "good", for example, "the pioneers had a good rest," evoked a conditioned reflex, and the content of the word "bad" turned out to be inhibitory. Then they experienced the action of phrases in which the words "good" and "bad" were replaced by similar ones in meaning, for example, "the pioneer is doing great" or "the student responds poorly." A distinct conditioned reaction occurred to the first phrase, but there was no reflex to the second. Finally, statements were used that spoke of good or bad only in their most general meaning. The results of this experiment are presented in table. 19.

Table 19. Conditioned salivary reflexes to verbal stimulation in a 13-year-old boy (according to V.D. Volkova)

Combination number // Conditional verbal stimulus // Salivation, drops / 30 s // Note

50 // Good // 18 // Backed Up

12 // Bad // 1 // Not backed up

51 // Good // 16 // Backed Up

1 // Leningrad is a wonderful city // 15 // "

1 // The student did not pass the exam // 2 // Not supported

52 // Good // 15 // Backed Up

1 // Brother offends sister // 1 // Not supported

1 // My brother is seriously ill // 2 // ""

1 // The enemy army was defeated and destroyed // 24 // Backed up

1 // The student passed the exam mediocre // 10 // "

From table. It can be seen that, according to objective indicators of the magnitude of conditioned reflexes, verbal signals "good" or "bad" continuously expanded their content up to the most general concepts of school duties "the student did not pass the exams" and the patriotic consciousness "the enemy army was defeated and destroyed."

2. Simultaneous formation and restructuring of time signals of the system. While the temporary connections of the first signaling system are developed only gradually as a result of a number of combinations, the temporary connections of verbal conditioned reflexes are formed immediately in one step. For example, you can explain to a visitor how to find the house he needs, and a person who has never been in this city will come straight to their destination (how much "trial and error" will the animal make until it finds the right path in the maze?).

Also, verbal cancellation of the conditioned reflex occurs simultaneously. A person, having read the announcement on the door of the dining room “closed for repairs,” will stop going there (how many days will the dog feeding there be running to the backyard of the dining room in vain until the complete extinction of its conditioned food reflex finally comes?).

All the main acts of conditioned reflex activity are simultaneously carried out in the second signaling system, for example, the development of differentiations (“cross the street at a green traffic light and do not cross at a red one”), delays (“turn on the TV, wait until the image appears”) and etc. The strength of such instantly formed connections and the ease of their conditional renewal underlies memory.

3. Display in the second signaling system of temporary connections formed in the first, and vice versa. The following observations can serve as an example.

A conditioned motor reflex to the sound of a bell was developed in children. After that, in one of the experiments, instead of turning on the bell, the experimenter uttered the word “bell”. The subject responded to this word with the same reaction as to the sound of the bell. The same effect was produced by the inscription "call" when presented to the subject.

Consequently, when the human brain forms a conditioned reflex even to a specific signal of the first system, then the response is simultaneously associated with its verbal designation, i.e. the signal of the second system. This happens as a result of the fact that each specific signal is included as one of the members in the synthetic word complex.

Selective irradiation of conditioned excitation within the verbal complex from each of its members manifests itself in the form of "transfer" of connections from the first signaling system to the second. So, both differentiations and complex relationships of stimuli can be "transferred" up to a complete picture of a stereotype. On the contrary, the "transfer" of connections from the second signaling system to the first is found in the fact that conditioned reactions developed to verbal stimuli are reproduced according to the signals of specific phenomena, which are indicated by the given word.

The interaction of signaling systems improves with age. Thus, the verbal report of children about the acting specific conditioned stimuli becomes full-fledged only starting from the age of 7-8.

4. The abstraction of a concept expressed by a word is inversely related to the strength of its connection with specific stimuli of reality. This property is revealed, for example, in the following experiment.

The child developed a conditioned salivary reflex to a word denoting the name of a certain bird. The magnitude of the reflex was 7–8 drops of saliva. When the generalizing word "birds" was tested, it turned out that it has a conditioned effect even stronger than the primary verbal stimulus. It produced 10 drops of saliva. However, an even broader generalization, expressed by the word “fly,” turned out to be a less strong conditioned stimulus for the salivary reflex, the magnitude of which dropped to 4–5 drops. Finally, the greatest degree of generalization of living things by the word "live" resulted in only 1 drop of saliva.

Consequently, the more abstract the concept, the wider the scope of its generalization, the further it stands from reality, the weaker the connection of its verbal signal with the specific signal of the main conditioned reaction.

5. Higher fatigue and susceptibility to external influences of the reflexes of the second signal system in comparison with the first. This naturally follows from the phylogenetic youth and the high sensitivity of the reflexes of the second signaling system. Therefore, for example, intense mental work is reflected primarily in the state of verbal reflexes, while in reflexes to specific stimuli, no signs of fatigue are yet manifested.

At the beginning and at the end of the school day, the schoolchildren studied conditioned motor reflexes to sound and to the word "bell" pronounced by the experimenter. It turned out that the conditioned reflex to the sound of the bell, i.e. carried out on a specific signal did not detect any changes during the school day. At the same time, the reflex to the word "call", i.e. carried out by means of the second signaling system, has undergone significant changes. The latent period of the conditioned reaction lengthened, and its magnitude decreased.

The higher sensitivity of the reflexes of the second signaling system to chemical influences manifested itself, for example, in a known sequence of phenomena drunkenness... At first, the ability to make conscious, reasonable judgments is lost, i.e. the activity of the second signal system suffers, and only later do the reflexes of the first signal system begin to be disturbed.

Localization of the central mechanisms of speech activity and the pairing of the work of the hemispheres. Although the activity of the second signaling system, which generalizes and abstracts in the form of concepts, complexes of different modal signals, covers all the basic mechanisms of the brain (sensory, motor and associative), the performance of various acts of speech function is associated with certain structures of the higher parts of the human brain. These structures, named centers of speech, were identified in clinical observations and designated by the names of the researchers who described them (Fig. 102). So, the motor center of Broca's speech, the defeat of which causes a disorder of the movements that carry out oral speech, is located at the base of the inferior frontal gyrus. Auditory Center for Wernicke's Speech, if damaged, the ability to understand the meaning of the words heard is lost, occupies the posterior third of the superior temporal gyrus. Optical speech center, the pathology of which makes it impossible for a person to recognize what is written is located in the angular gyrus.

Rice. 102. The location of some special parts of the verbal signal analyzer in the human cerebral cortex:

1 - speech movements (Broca's center), 2 - speech articulation, 3 - hand movements when writing, 4 - analysis of speech sounds, 5 - oral verbal signals (Wernicke center), 6 - written verbal signals, 7 - visual analysis

The predominant localization of "speech centers" in the left hemisphere is associated in the evolution of the human brain with the leading role of its right hand... Thus, along with the paired work of the cerebral hemispheres in many types of its activity, there is also some inequality in relation to the implementation of its higher functions, mainly by the left hemisphere. On this basis, it is assumed that left hemisphere performs the main functions of the second signaling system. Observations of patients undergoing unilateral therapeutic electroshock were cited as evidence.

When the activity of the left hemisphere was inhibited in this way, speech, understanding of words, the ability to read text, to solve logical problems were sharply impaired, but the ability to recognize surrounding objects, to understand the meaning of everyday sounds, for example, a bell to open a door, placing plates on the table, spoons, etc. forks for cooking, etc., as well as the emotional perception of music. When the right hemisphere was subjected to electric shock, the understanding of everyday signal sounds and the emotional perception of music were impaired, but all manifestations of speech and writing remained.

In favor of the opinion about the separation of the functions of the left and right hemispheres, the results of a study of the reactions of the electroencephalogram to verbal and non-verbal appeals to a person are cited. In the first case, the desynchronization reaction was more pronounced with the leads on the left side, in the second - on the right. Studies of ECoG, focal EPs, and impulse responses of neurons in cats have shown that when a conditioned reflex is formed, activity is first synchronized in symmetrical parts of the hemispheres, then its predominance is recorded in the hemisphere, contralateral to the reinforcement side (the first manifestations of concentrated in this hemisphere (strong conditioned reflex).

Human typology. To diagnose human typology, the method of studying conditioned motor reflexes formed on verbal reinforcement is widely used. Typological differences can also be found in changes in the electrical activity of the brain under the action of intermittent stimuli of increasing intensity (Fig. 103). Here, the strength, balance and mobility of nervous processes are reflected in the most tolerable force of the stimulus, the excess of which leads to an extreme suppression of electrical activity, in the degree of change in activity and the rapidity of development of these changes. Typological features are also revealed when testing ready-made speech-motor reflexes that have developed during life, for example, in the strength relations of a conditioned stimulus (volume of an order) and a reflex (magnitude of a response movement) (Fig. 104).

Rice. 103. Installation for the study of changes in the basic electrical activity of the brain under the action of intermittent stimuli of increasing intensity (according to the method of M.N. Livanov):

1 - metal screen of the cockpit for the test subject, 2 - illuminator with lamp (4) and shutter (3), rotating motor (5), 6 - rheostat of a stepwise increase in the intensity of light stimulation, 7 - the inclusion of light irritation transmitted by the cord (8) key (9) for marking on the electroencephalogram, 10 -reduction of brain potentials

Rice. 104. Individual differences in the flow of ready-made speech-motor reflexes when the strength of the verbal signal changes (the amount of movement performed by order is recorded). A B C- reactions in different subjects with greater (A) or less (V) by the power of nervous processes: I-V- the degree of loudness of the order from a very quiet (I) to deafeningly loud (V)

Typological differences also appear in everyday behavior. So, descriptions of the life of famous writers gave grounds to attribute I.S. Turgenev to the sagviniks, I.A. Krylova to phlegmatic people, A.S. Pushkin to choleric people, and N.V. Gogol to the melancholic. The presence in a person of two signaling systems, jointly carrying out his mental activity, complicated the typology of people. In addition to differences in the general types of the nervous system, there are individual characteristics of the degree of participation of verbal and specific signals in the complex analytical and synthetic work of the human brain. They are expressed in the volume of use of the first and second signaling systems and determine special types of human higher nervous activity. These differences are only of a relative nature, since in every impression, movement of thought and action of a person, both systems participate with the leading role of the conscious, verbal.

According to the ratio of the activity of the first and second signaling systems, there are different types of people. Extreme cases of such typological relations I.P. Pavlov called it mental and artistic. The thinking type is characterized by a sharp dominance of the second signaling system over the first and, therefore, a strong tendency towards abstract thinking. People with a thinking type perceive their surroundings not so much in the form of direct vivid pictures of life, but in the form of verbal, generalized definitions of it. The artistic type is characterized by a lesser than usual predominance of the second signal system over the first and, therefore, a tendency towards concrete thinking. These are people who vividly and vividly perceive their surroundings in images, sounds, colors, touches and smells. A vivid manifestation of the artistic type of thinking of I.P. Pavlov considered the work of L. Tolstoy. However, as a rule, people have a mixed (medium) type of nervous activity. Later functional studies (OM Teplov, 1956) revealed the connection between the state of nervous processes and the personality characteristics of a person; it was also shown that high sensitivity can compensate for the weakness of the human nervous system and ensure the usefulness of its activity. Research in the field of human typology is complicated by the fact that it is necessary to distinguish between general and particular properties of his nervous system (V.D. Nebylitsyn, 1976). Private properties can manifest to varying degrees, for example, different sensory systems of the brain, causing the comparative severity of visual, auditory, or other components of perception. General properties characterize the activity of the integrative mechanisms of the brain that determine the personality of a person at all levels of its manifestation, carried out mainly by the anterior regions of the cortex in interaction with the subcortical structures. Electrophysiological studies have shown that the activity of these particular parts of the brain is characteristic of the subjects who found high levels of motor and mental activity.

Neurophysiological mechanisms of human thinking

The study of how the brain "makes a thought" has only recently become a subject of physiology. Therefore, information on the neurophysiological mechanism of the activity of the second signaling system is still extremely limited. At the current level of knowledge, in order to characterize the features of this activity, it is necessary to study not so much its physiological mechanism as the localization and conditions for the formation of the conditioned connections that arise in this case. At the present time, so far scattered information has been accumulated about the nervous processes that are played out in the structures of the human brain during his mental activity. Some results were obtained when clarifying general issues reflection of human thinking processes in electrical indicators of the activity of the nervous mechanisms of the brain, as well as in the study of the processes of perception, decision-making and the formation of concepts. However, there are still unclear and controversial issues, starting with the value of electrical indicators for determining nervous processes and ending with the problem of human intelligence.

Electrical indicators of the main processes of human brain activity. The human brain, like that of animals, generates electrical potentials of the background rhythm, responds with evoked potentials to afferent stimuli, develops infraslow potentials, and detects the impulses of individual neurons. According to these indicators, one can, to some extent, judge the course of nervous processes in the higher parts of the brain, evaluate the comparative participation of its structures in the formation and implementation of acts of higher nervous activity.