Name the types of inhibition of conditioned reflexes and explain the reasons for their occurrence and the main differences. What is the significance of the inhibition of conditioned reflexes for the organism?

Explanation.

1. Types of inhibition of conditioned reflexes: external (unconditioned) inhibition and internal (conditioned) inhibition.

2. The reasons for their occurrence and the main differences:

External (unconditioned) inhibition - arises according to the principle of an unconditioned reflex - develops as a result of the action of a new external strong stimulus, which leads to the emergence of a new external relatively strong stimulus, which leads to the emergence of a new focus of excitation in the cortex and this focus causes inhibition of the old one.

Peculiarities:

Unconditional inhibition is an innate form of inhibition; it is inherent in all individuals of a given species;

It doesn't take time for it to occur;

It can develop in any part of the central nervous system.

Internal (conditioned) inhibition - is carried out according to the principle of a conditioned reflex.

Conditional inhibition occurs when the conditioned signal is not reinforced. In the cerebral cortex, a temporary reflex connection ceases to be carried out - a gradual extinction of the response is observed.

Peculiarities:

This is an individual reaction of the body acquired during life;

Requires certain conditions, for its implementation it is necessary to develop;

It develops in the neurons of the cerebral cortex.

An example of external inhibition: salivation to light stops with a sharp, sudden, strong sound.

An example of internal inhibition: salivation to light fades and disappears if it is not reinforced by feeding.

3. Significance for the organism of inhibition of conditioned reflexes:

inhibition of conditioned reflexes ensures that conditioned reflexes correspond to the conditions of existence and at the same time delays conditioned reflexes that have no or have lost their significance for life.

a more detailed analysis and synthesis of information is carried out - along with conditioned reflexes, they ensure the adaptation of the body to changing environmental conditions.

Provides (together with excitation) the normal activity of all organs and the body as a whole. It has a protective value (primarily for the nerve cells of the cerebral cortex), protecting the nervous system from overexcitation.

Note (not specified in the criteria).

External (unconditioned inhibition) - transcendental inhibition: the conditioned reflex obeys the law of the strength of stimulation (with an increase in the strength of the stimulus to a certain limit, the response increases). With a further increase in the strength of the stimulus, conditioned reflexes are inhibited. Mechanism: the conditioned reflex sharply increases the strength and exceeds the threshold of performance of the neurons of the cerebral cortex. As a result, in the brain section of the analyzer there is an outrageous inhibition. Meaning: Protects the neurons of the cerebral cortex from exhaustion.

Conditioned inhibition - differential value - accurate discrimination of close stimuli. Mechanism: differentiation of stimuli occurs in the neurons of the brain analyzer.

The nervous system functions due to the interaction of two processes - excitation and inhibition. Both are the form of activity of all neurons.

Excitation is a period of vigorous activity of the body. Outwardly, it can manifest itself in any way: for example, muscle contraction, salivation, students' answers in the lesson, etc. Excitation always gives only an electronegative potential in the tissue excitation zone. This is his indicator.

Braking is just the opposite. It sounds interesting that inhibition is caused by excitation. With him nervous excitement temporarily stops or weakens. When braking, the potential is electropositive. Human behavioral activity is based on the development of conditioned reflexes (UR), the preservation of their connections and transformations. This becomes possible only with the existence of excitation and inhibition.

The predominance of excitation or inhibition creates its own dominant, which can cover large areas of the brain. What happens first? At the beginning of excitation, the excitability of the cortex hemispheres increases, which is associated with a weakening of the process of internal active inhibition. In the future, these normal force relationships change (there are phase states) and inhibition develops.

What is braking for?

If for some reason the vital significance of some conditioned stimulus is lost, inhibition cancels its effect. It thus protects the cells of the cortex from the action of irritants that have passed into the category of destructive and become harmful. The reason for the occurrence of inhibition lies in the fact that any neuron has its own working capacity limit, beyond which inhibition occurs. It is protective in nature, because it protects the nerve substrates from destruction.

Types of braking

Inhibition of conditioned reflexes (TUR) is divided into 2 types: external and internal. External is also called innate, passive, unconditional. Internal - active, acquired, conditional, its main feature - innate character. The innate nature of unconditioned inhibition means that for its appearance it is not necessary to specially develop and stimulate it. The process can occur in any department of the central nervous system, including in the cortex.

The limiting inhibition reflex is unconditioned, i.e., congenital. Its occurrence is not connected with the reflex arc of the inhibited reflex and is outside it. Conditional inhibition is developed gradually, in the process of SD formation. It can only occur in the cerebral cortex.

External braking is divided, in turn, into induction and beyond-marginal braking. To inner view include extinction, retardation, differential inhibition and a conditional brake.

When external inhibition occurs

External inhibition occurs under the influence of stimuli outside the working conditioned reflex. They are outside the experience of this reflex, at first they can be new and strong. In response to them, an indicative reflex is first formed (or it is also called a reflex to novelty). The response is excitement. And only then it slows down the existing SD until this extraneous irritant ceases to be new and disappears.

Such extraneous stimuli most quickly extinguish and slow down newly established young SDs with weak, strengthened connections. Strongly developed reflexes are extinguished slowly. Fading inhibition can also occur if the conditioned signal stimulus is not reinforced by an unconditioned one.

State expression

Extreme braking in the cerebral cortex is expressed by the onset of sleep. Why is this happening? Attention is weakened by monotony, and the mental activity of the brain decreases. M. I. Vinogradov also pointed out that monotony leads to rapid nervous exhaustion.

When there is extreme braking

It develops only with stimuli that exceed the limit of neuronal performance - superstrong or several weak stimuli with total activity. This is possible with prolonged exposure. What happens: Prolonged nervous excitement violates the existing "law of force", which states that the stronger the conditioned signal, the stronger the arc of the reflex appears. That is, the process is first spurred on. And already further, the conditioned reflex reaction with a further increase in strength gradually declines. After stepping over the limits of the neuron, they turn off, protecting themselves from exhaustion and destruction.

So, such transcendental inhibition occurs under the following conditions:

1. The action of a common stimulus for a long time.
2. A strong irritant acts for a short time. Transmarginal inhibition can also develop with mild stimuli. If they act simultaneously, or their frequency increases.

The biological significance of unconditional transcendental inhibition boils down to the fact that exhausted brain cells are provided with a respite, rest, which they badly need, for their subsequent vigorous activity. Nerve cells are designed by nature to be the most intense for activity, but they are also the fastest to tire.

Examples

Examples of transcendent inhibition: a dog developed, for example, a salivary reflex to a weak sound stimulus, and then began to gradually increase it in strength. The nerve cells of the analyzers are excited. Excitation first increases, this will be indicated by the amount of saliva secreted. But such an increase is observed only up to a certain limit. At some point, even a very strong sound does not cause saliva, it will not stand out at all.

Extreme excitation has been replaced by inhibition - that's what it is. This is an outrageous inhibition of conditioned reflexes. The same picture will be under the action of small stimuli, but for a long time. Prolonged irritation quickly leads to fatigue. Then neuron cells slow down. An expression of such a process is sleep after experiences. This is a protective reaction of the nervous system.

Another example: a 6-year-old child is involved in a family situation where his sister accidentally knocked over a pot of boiling water on herself. There was a commotion in the house, screams. The boy was very frightened and after a short period of strong crying he suddenly fell deeply asleep on the spot and slept all day, although the shock was still in the morning. The nerve cells of the baby's cortex could not endure excessive stress - this is also an example of transcendental inhibition.

If you do one exercise for a long time, then it no longer works. When classes are long and tedious, at the end his students will not answer correctly even easy questions that they had no problem overcoming at first. And it's not laziness. Students at a lecture begin to fall asleep when the lecturer's monotonous voice or when he speaks loudly. Such inertia of cortical processes speaks of the development of limiting inhibition. For this, breaks and breaks between couples for students were invented at school.

Sometimes strong emotional outbursts in some people can end in emotional shock, a stupor, when they suddenly become constrained and quiet.

In a family with small children, the wife screams and demands to take the children out for a walk, the children clamor, scream and jump around the head of the family. What will happen: he will lie down on the sofa and fall asleep. An example of extreme inhibition can also be the starting apathy of an athlete before competing in competitions, which will negatively affect the result. By its nature, this Overlimiting inhibition performs a protective function.

What determines the performance of neurons

The excitability limit of neurons is not a constant. This value is variable. It decreases with overwork, exhaustion, illness, old age, the effect of poisoning, hypnotization, etc. Limiting inhibition also depends on the functional state of the central nervous system, on the temperament and type of the human nervous system, its balance of hormones, etc. That is, the strength of the stimulus for each person individual.

Types of external braking

The main signs of transcendental inhibition are: apathy, drowsiness and lethargy, then consciousness is disturbed by the type of twilight, the result is loss of consciousness or sleep. The extreme expression of inhibition is the state of stupor, unresponsiveness.

Induction braking

Induction inhibition (permanent brake), or negative induction - at the moment of manifestation of any activity, a dominant stimulus suddenly arises, it is strong and suppresses the manifestation of the current activity, i.e., induction inhibition is characterized by the cessation of the reflex.

An example would be the case when a reporter photographs an athlete lifting the barbell and his flash blinds the weightlifter - he stops lifting the barbell at the same moment. The teacher's shout stops the student's thought for a while - an external brake. That is, in fact, a new, already stronger reflex has arisen. In the example of the teacher's yell, the student has a defensive reflex when the student concentrates to overcome the danger, and therefore it is stronger.

Another example: a person had a pain in his arm and suddenly a toothache appeared. She will overcome the wound on her arm, because toothache is a stronger dominant.

Such inhibition is called inductive (based on negative induction), it is permanent. This means that it will arise and never subside, even with repetition.

Extinguishing brake

Another kind of external inhibition that occurs in the form of SD suppression under conditions that lead to the appearance of an orienting reaction. This reaction is temporary, and the causal external inhibition at the beginning of the experiment ceases to operate later. Therefore, the name is - fading.

Example: a person is busy with something, and a knock on the door causes him to first orienting reaction"who's there". But if it is repeated, the person stops responding to it. When getting into some new conditions, it is difficult for a person to orient himself at first, but, getting used to it, he no longer slows down when doing work.

Development mechanism

The mechanism of transcendental inhibition is as follows - with an extraneous signal, a new focus of excitation appears in the cerebral cortex. And it, with monotony, depresses the current work of the conditioned reflex according to the mechanism of the dominant. What does it give? The body urgently adapts to the conditions of the environment and the internal environment and becomes capable of other activities.

Phases of extreme braking

Phase Q - initial braking. The man so far only froze in anticipation of further events. It is possible that the received signal will disappear by itself.

Phase Q2 is the phase of active response, when a person is active and purposeful, responds to the signal adequately and takes action. Focused.

Phase Q3 - prohibitive inhibition, the signal continued, the balance was disturbed, and the excitation was replaced by inhibition. The person is paralyzed and lethargic. There are no more jobs. It becomes inactive and passive. At the same time, he may begin to make blunders or simply “turn off”. This is important to consider, for example, for developers of alarm systems. Excessively strong signals will only cause the operator to brake instead of actively working and taking emergency measures.

Transboundary inhibition protects nerve cells from exhaustion. For schoolchildren, such inhibition occurs in the classroom, when the teacher explains educational material too loud from the start.

Physiology of the process

The physiology of transboundary inhibition is formed by irradiation, the spilling of inhibition in the cerebral cortex. In this case, most of the nerve centers are involved. Excitation is replaced by inhibition in its most extensive areas. The limiting inhibition itself is the physiological basis of the initial distraction, and then the inhibitory phase of fatigue, for example, in students in a lesson.

Braking value of external

The meaning of transcendental and induction (external) inhibition is different: induction is always adaptive, adaptive. It is associated with a person's response to the strongest external or internal stimulus to this moment time, be it hunger or pain.

This adaptation is the most important for life. To feel the difference between passive and active inhibition, here is an example: a kitten easily caught a chick and ate it. A reflex has developed, he begins to throw himself at any adult bird in the same hope of catching it. This fails - and he switches to the search for prey of a different kind. The acquired reflex is actively extinguished.

The value of the limit of neuronal performance even for animals of the same species does not match. As do people. In animals with a weak central nervous system, old and castrated animals, it is low. Its decrease was also noted in young animals after prolonged training.

So, transcendental inhibition leads to a stupor of the animal, the protective reaction of inhibition makes it invisible in case of danger - this is the biological meaning of this process. It also happens in animals that the brain turns off almost completely during such inhibition, even leading to imaginary death. Such animals do not pretend, the strongest fear becomes the strongest stress, and they really seem to die.

Transmarginal inhibition (protective inhibition) is an unconditioned (congenital) inhibition that occurs in the central nervous system in response to a stimulus when its intensity exceeds the possible limit. The value of the limit, which reflects the performance of nerve cells, is not the same for animals of the same species. Thus, the limit of working capacity is quite low in animals with a weak central nervous system, old and castrated animals. Its decrease was noted in dogs after prolonged training or training sessions. Z. t. also develops with the simultaneous action of several weak stimuli, as well as in the case of an increase in the frequency of the conditioned stimulus. It is believed that the biological meaning of Z. t. is that it protects the nerve cells from overwork or leads to a stupor of the animal, which makes it invisible in case of danger.

Dictionary of trainer. V. V. Gritsenko.

See what "Outrageous braking" is in other dictionaries:

extreme braking- Category. form of inhibition. Specificity. The development of inhibition processes when the stimulation force reaches a critical, biologically acceptable limit. Psychological dictionary. THEM. Kondakov. 2000...

Ultimate Braking- the development of inhibition processes when the stimulation force reaches a critical, biologically acceptable limit ... Psychological Dictionary

Extreme braking- a form of external inhibition (See External inhibition), which occurs mainly in the cells of the cerebral cortex with an excessive increase in the strength, duration or frequency of irritation. It develops with the deepening of parabiosis of nerve cells, ... ... Great Soviet Encyclopedia

Extreme braking- protective inhibition is a type of unconditioned (innate) inhibition that occurs in response to the action of stimuli of great intensity. Z.t. develops when there is a danger of overstrain of nerve cells, exceeding their working capacity limit. ZT… … Correctional Pedagogy and special psychology. Vocabulary

EXTREME BRAKING- [from Greek. tormos, a hole for inserting a nail that delays the rotation of the wheel] protective inhibition as a type of unconditioned (innate) inhibition that occurs in response to the action of stimuli of great intensity. Z. t. appears when ... ...

protective (outrageous) braking- the second stage of cortical unconditioned inhibition, which consists in a sharp decrease in the activity of nerve cells, caused by excessive excitation of cortical structures and thereby providing real opportunity saving or restoring... ... encyclopedic Dictionary in psychology and pedagogy

BRAKING EXCELLENT- inhibition that occurs under the action of stimuli (stimuli) that excite the corresponding cortical structures above their inherent limit of working capacity, and thereby provides a real possibility of its preservation or restoration (see ... Psychomotor: Dictionary Reference- variety cortical inhibition; in contrast to conditional inhibition, it occurs without preliminary development. T. b. includes: 1) induction (external) inhibition emergency cessation of conditioned reflex activity (see conditional ... ... Great Psychological Encyclopedia

Extreme braking

This type of inhibition differs from external and internal in terms of the mechanism of occurrence and physiological significance. It occurs when the strength or duration of the action of the conditioned stimulus is excessively increased, due to the fact that the strength of the stimulus exceeds the efficiency of the cortical cells. This inhibition has a protective value, as it prevents the depletion of nerve cells. In its mechanism, it resembles the phenomenon of "pessimum", which was described by N.E. Vvedensky.

Transmarginal inhibition can be caused not only by the action of a very strong stimulus, but also by the action of a small in strength, but prolonged and uniform in nature, stimulus. This irritation, constantly acting on the same cortical elements, leads them to exhaustion, and, consequently, is accompanied by the appearance of protective inhibition. Transmarginal inhibition develops more easily with a decrease in working capacity, for example, after a severe infectious disease, stress, and more often develops in older people.

All types of conditioned inhibition are of great importance in human life. Endurance and self-control, accurate recognition of the objects and phenomena around us, and finally, the accuracy and clarity of movements are impossible without braking. There is every reason to believe that inhibition is based not simply on the suppression of conditioned reflexes, but on the development of special inhibitory conditioned reflexes. The central link of such reflexes is the inhibitory nervous connection. The inhibitory conditioned reflex is often called negative as opposed to the positive conditioned reflex.

Inhibition of an undesirable reaction is associated with a large waste of energy. Competing stimuli, as well as other causes related to the physical state of the organism, can weaken the process of inhibition and lead to disinhibition. During disinhibition, actions are manifested that were previously eliminated by braking processes.

Conclusion

The functioning of the conditioned reflex mechanism is based on two main nervous processes: on the process of excitation and on the process of inhibition. As the conditioned reflex develops and becomes stronger, the role of the inhibitory process increases. Inhibition is a factor contributing to the adaptation of the organism to its surrounding conditions. Inhibition also weakens the processes of excitation in the nervous system and ensures the stability of its work.

In the absence of inhibition, the processes of excitation would increase and accumulate, which would inevitably lead to the destruction of the nervous system and the death of the organism.

PRACTICAL PART

MUSCLE-JOINT SENSITIVITY

The subject sits down at the kinematometer and closes his eyes. The researcher alternately sets the angle that the subject must subsequently reproduce on the large and small scales of the device. AT

during the performance of this exercise, the following data were obtained (given and performed by the test subject) 48, 52, 45 with a given value of 50 (large scale) 25, 27, 27 with a given value of 25 (small scale) for the first subject and 55, 51 , 54 for a given value of 50 (large scale) 30, 28, 29 for a given value of 30 (small scale) for the second subject.

Based on this, we can say that fine articular-muscular sensitivity is higher, in addition, one of the subjects showed better results, which suggests that his joint-muscular sensitivity is better developed.

TACTILE SENSITIVITY

The subject stretches his arms forward and closes his eyes, opens his palms up, and the researcher simultaneously, without pressure, lowers a weight of 1 to 5 g on the palms of both hands.

By changing the ratio of the weight of the load in the palm of the hand, the researcher determines the minimum difference in the weight of the load that the researcher is able to distinguish. In the course of this exercise, the following data were obtained (the minimum difference in the weight of the load that the subject is able to distinguish) 1 gr. for both test subjects. This is explained by the difference threshold of tactile sensitivity, i.e. the minimum difference in the strength of two stimuli of the same type (weight of cargo on different palms) necessary to change the intensity of sensation.

The difference threshold is measured by a relative value, which shows what part of the initial strength of the stimulus must be added (or reduced) in order to get a barely noticeable sensation of a change in the strength of these stimuli. To feel a minimal increase in the pressure of the load on the hand, an increase in the initial strength of irritation by 1/17 of its initial value is necessary, regardless of the units in which this pressure intensity is expressed.

The subject closes his eyes, and the researcher at the same time, without pressure, lowers the needles of the legs of the compass on his skin. Consistently reducing the distance between the needles of the legs of the compass, the researcher determines the minimum distance between them, which is perceived by the researcher when touched as the impact of two stimuli.

In the course of this exercise, the following data were obtained (the minimum distance between the needles of the legs of the compass, perceived when touched as the impact of two stimuli) 1 mm for both subjects. This is explained by the phenomenon of the spatial threshold of tactile sensitivity, i.e. the minimum distance between two different, but adjacent points, the simultaneous stimulation of which causes two independent, distinct tactile sensations.

Touch sensations occur when a mechanical stimulus causes deformation of the skin surface. When pressure is applied to a small area of ​​skin (less than 1 mm), the greatest deformation occurs precisely at the site of direct application of the stimulus. If pressure is exerted on a large surface (more than 1 mm), then it is distributed unevenly, its least intensity is felt in the depressed parts of the surface, and the greatest along the edges of the depressed area.

ARISTOTLE'S EXPERIENCE

The subject rolls a small ball between the index and middle fingers, while he makes sure that he perceives it as one object. If the subject rolls the same ball between the crossed fingers so that it is between the medial (inner) surface of the index finger and the lateral (outer) surface of the middle finger, he can verify that the perception of the presence of two balls is created. This is due to the phenomenon of the illusion of touch, which can arise under the influence of immediately preceding perceptions. In this case, the fact that the medial surface of the index and the lateral surface of the middle finger under normal conditions can be simultaneously irritated by only two objects. There is an illusion of irritation with two objects, because. in the brain there are two centers of excitation.

PUPIL REACTION

The subject becomes facing daylight, and the researcher measures the width of his pupil. Then one eye of the subject is covered with a hand and the width of the pupil of the open eye is measured. Then the closed eye is opened and the width of its pupil is again measured.

During this exercise, the following data were obtained (pupil width) 5 - 7 - 5 mm and 6 - 8 - 6 mm for the first and second subjects, respectively. Thus, the pupil width changed by an average of 2 mm, and the pupillary reaction time did not exceed 1 sec for both subjects. When both eyes were closed for 30 seconds, the pupil width was 5 - 9 - 5 mm and 6 - 10 - 6 mm, respectively, while the pupillary reaction time did not exceed 1 second.

The researcher fixes his gaze on a distant object, and the researcher measures the width of his pupil, then the researcher fixes his gaze on an object 15 cm distant, and the researcher again measures the width of his pupil. During this exercise, the following data were obtained (pupil width) 5 - 3 mm and 6 - 4 mm for the first and second subject, respectively. Thus, the pupil width changed by an average of 2 mm, and the pupillary reaction time did not exceed 1 sec for both subjects.

From the foregoing, it follows that the reaction of the pupil to light in both subjects is at the same level, and the difference in indicators is due to individual differences (in this case, pupil width at rest).

SPHERICAL ABERATION

The subject closes one eye, and brings a pencil close to the other, to such a distance that the image is blurry, then a sheet of paper with a hole 1 mm in diameter is placed between the pencil and the eye, and the object becomes clearly distinguishable. This is explained by the fact that spherical aberration is better expressed for the central beams. During this exercise, the following data were obtained (the distance from the eye to the pencil at the moment when it becomes less clearly distinguishable) 10 cm and 11 cm for the first and second subjects, respectively.

Looking at a pattern of vertical and horizontal lines, the subject fixes his gaze on the vertical and then on the horizontal lines and makes sure that he cannot see the horizontal and vertical lines equally clearly.

The subject looks through a thin grid at the printed text from a distance of 50 cm from the eye, if you fix the letters with your eyes, then the threads of the grid are less visible, and if you fix the grid with your eyes, then the letters.

From the foregoing, it follows that the subject cannot simultaneously clearly see two objects at different distances due to the fact that the optical system of the eye has spherical aberration, i.e. the focus of the peripheral rays is closer than the focus of the central ones.

DETECTION OF ASTIGMATISM

The subject looks at a pattern consisting of vertical and horizontal lines of the same thickness, while both subjects noted that the vertical lines appear visually more distinct. As the drawing approaches the eye, the horizontal lines become more distinct. In the course of this exercise, the following data were obtained (the distance from the eye to the drawing at the moment when the horizontal lines become clearer) 10 cm and 11 cm for the first and second subjects, respectively. This is explained by the fact that the rays coming from the horizontal lines at the initial position of the pattern were in front of the retina, and when the pattern approached the eye, the points of convergence of the rays moved to the retina. When the picture is rotated, the subject's idea of ​​the thickness of the lines is constantly changing according to the change in their position to vertical or horizontal. This is due to the fact that the rays coming from the horizontal and vertical lines are alternately in front of the retina and on the retina.

BLIND SPOT DETECTION

The subject fixes his gaze in the figure in the form of a black rectangle, in the left half of which there is a white circle, and in the right half there is a white cross. Closing the right eye, the subject with his left eye fixes the cross located on the right side of the picture. The drawing is brought closer to the eye until the circle falls out of sight. In the course of this exercise, the following data were obtained (the distance from the eye to the drawing at the moment when it falls out of sight) 11 cm for both subjects.

The subject fixes with his right eye a cross located in the upper left corner of a white sheet of paper. A pencil wrapped in white paper (except for the sharpened tip) moves from the upper right corner towards the cross.

The subject is convinced that at a certain distance from the cross the pencil becomes less distinguishable, but as it approaches the cross further, its image becomes clearer again.

During this exercise, the following data were obtained (distance from the nodal point of the eye to the retina) 18.5 and 18.0 mm for the first and second subjects, respectively, and (diameter of the blind spot) 2.7 mm for both subjects.

This is due to the fact that there is a blind spot on the retina of the eye (the entry point of the neurovascular bundle, the area that does not have sensitive elements), i.e. the area where the image does not appear.

DETERMINATION OF VISUAL ACUITY

The subject fixes his gaze on a drawing consisting of two parallel lines spaced 1 mm apart, then he moves away from the drawing until both lines become visible as one line.

In the course of this exercise, the following data were obtained (the distance from the eye to the drawing, in which two parallel lines perceived as one) 3 m for both subjects and (angle of view) 0.006 mm for both subjects.

This is due to the fact that two points in space are perceived by the optical system of the eye as separate only if the distance between them is greater than or equal to 5 μm, in our case 6 μm, which indicates a slight decrease in the sensitivity of the optical system of the eye in both subjects

SEQUENTIAL VISUALS

The subject fixes his gaze on the drawing in the form of a black square for a certain time, and then shifts his gaze to white wall. The subject is convinced that for some time a subtle image of a black square remains on the wall.

In the course of this exercise, the following data were obtained (the time during which the image of a black square is stored on a white wall) is less than 1 second for both subjects.

This phenomenon is explained by the property of the nervous system to maintain excitation for some time after the cessation of the irritating factor.

FIELDS OF VISION

The subject fixes his gaze on any object, while with one of his eyes he looks through a paper cone with a narrow hole. The subject is convinced that visually the object seems to be perforated.

This is explained by the fact that the field of view of one eye is illuminated relatively stronger than the field of view of the other eye, the object attached to the cone is visible, but a small part of the field of view of the eye attached to the cone is illuminated even more, so the subject sees a hole in the object.

SIMULATED DEAFNESS

The subject reads a book aloud. After he has read a few sentences, the researcher taps a box of lead pieces against his ear. The researcher can make sure that the subject after that began to read louder. This does not happen in a deaf person. This experience is based on the fact that a person, with the help of an auditory analyzer, controls the intensity and correctness of his speech (semantic stresses, emotional coloring). In a noisy environment, a person increases the intensity of speech to a level at which others will hear it. A deaf person cannot exercise such control over his speech. I did this experience not only in the audience at the last session, but also at work, conducting a therapeutic reception of a convict with second-degree sensorineural hearing loss.

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Nervous activity is carried out as a result of the interaction of two main nervous processes - excitation and inhibition.

Excitation- a nervous process that brings the body into an active state. Externally, excitation is manifested, for example, in the contraction of a group of muscles or in the release of a secret. A more accurate indicator of excitation is the occurrence of an electronegative potential a in the excited area of ​​\u200b\u200bthe tissue.

Braking- a nervous process leading to a temporary cessation or weakening of the active state of the body. When braking, an electropositive potential occurs. The formation of conditioned reflexes, their connection, preservation and transformation are possible only when excitation interacts with inhibition.

In order to form a conditioned reflex to a certain stimulus, all reflexes to other stimuli that continuously act on the organism must be temporarily delayed. The process of inhibition also cancels the action of the conditioned stimulus if it has temporarily lost its vital significance. Finally, inhibition protects the nerve cells of the cortex from the destructive action of harmful stimuli.

Distinguish inhibition unconditional, or passive, and conditional, or active.

A feature of unconditioned inhibition is its innate nature. It does not require special development and is characteristic of all parts of the central nervous system. Conditioned inhibition, which is also called internal, occurs gradually in the process of formation of conditioned reflexes. It is peculiar only to the cerebral cortex.

To unconditional inhibition include external and transcendental inhibition, conditional (internal) include extinction, differential, delay braking and the so-called conditional brake.

External braking arises under the influence of extraneous stimuli to the formed conditioned reflex. A stimulus foreign to experience, especially a new and strong one, evokes an orienting reflex, and the excitation related to this reflex inhibits the conditioned reflex being developed until the foreign stimulus disappears or loses its novelty. In order to avoid the inhibitory effect of extraneous stimuli, special conditions are created for some laboratory experiments - isolated soundproof chambers.

It has been observed that young, weakly strengthened conditioned reflexes are most easily inhibited under the influence of extraneous stimuli.

The latest studies of the orienting reflex (E. N. Sokolov and others) prove its complex nature. It was found that orienting reflexes not only inhibit the formation of conditioned reflexes, but are also necessary condition their education. Any stimulus at the beginning of its action causes an orienting reaction of the organism, which increases the sensitivity of the corresponding analyzers. An indifferent stimulus, i.e., one that has lost the character of novelty under the given conditions of experience, does not evoke an orienting reaction until the moment when its action is combined with reinforcement. From the moment of the combination, each appearance of the conditioned stimulus will evoke an orienting reaction to itself, which increases the sensitivity of the analyzer and contributes to the formation of a conditioned connection.

Similar to external braking is inhibition, called negative induction.

Transmarginal inhibition occurs under the influence of super-strong, excessively prolonged and other harmful conditioned and unconditioned stimuli that exceed the limit of nerve cell performance. Transmarginal inhibition plays a protective role, as it protects nerve cells from unbearable stresses.

Let's give examples. At the dog produce a salivary reflex to a weak sound stimulus, and then gradually increase its strength. Accordingly, the strength of excitation in the nerve cells of the analyzers also increases, as can be judged by the intensity of salivation. However, this is observed up to a certain limit. At some point in the action of a very strong sound stimulus, a sharp drop in salivation occurs. The excitation of the limiting force is immediately replaced by deceleration. The same is observed with continuous and excessively prolonged action of the stimulus. Nerve cells, which differ from other cells in the body by a high intensity of activity, quickly get tired. With their continuous and prolonged irritation, fatigue develops faster, and the nerve cells go into a state of inhibition. Sleep occurs as a protective reaction of the nervous system from excessive stress.

There was such a case. A six-year-old child witnessed a difficult scene in the family: his sister accidentally knocked over a pot of boiling water on herself. There was a commotion in the house. The boy's fright was so strong that, after several minutes of desperate crying, he suddenly fell into a deep sleep and slept for several hours, although the incident occurred in the morning. The nerve cells of the cortex could not bear the excessive stress.

Strong emotional outbursts in some people reach the so-called "emotional shock", that is, sudden stiffness. The physiological basis of such a shock is also transcendental inhibition.

The excitability limit of nerve cells is not constant. It decreases due to prolonged fatigue, illness, the effects of toxic substances on the body. In addition, they matter individual characteristics people, the type of their higher nervous activity.

The simplest type of conditioned inhibition is the extinction of conditioned reflexes.

It arises as a result of their non-reinforcement. If the conditioned stimulus of the developed conditioned reflex is given several times in a row at short intervals without combining it with the unconditioned one, then the conditioned reflex will gradually disappear, fade away. Thus, a repeatedly given light signal, to which the dog developed a salivary reflex without reinforcement, instead of excitation, begins to cause inhibition. Pigeons flock to the feeder as long as there are grains in it; in the absence of food, their arrivals become less and less frequent, until they stop altogether. A child taught to wash his hands on his own, in the absence of control, gradually ceases to fulfill this hygienic requirement.

The extinction of conditioned reflexes underlies the forgetting caused by the absence of repetitions.

The following patterns of extinction have been established: young, weakly strengthened conditioned reflexes are easily extinguished; extinction develops the faster, the more often the conditioned stimulus is applied without reinforcement; conditioned reflexes formed on the basis of strong reinforcing stimuli fade slowly; the extinction of one conditioned reflex entails the weakening of others similar to the fading and fragile conditioned reflexes, etc. It is useful to use these patterns in the process of teaching students and in organizing independent work on the acquisition of knowledge and skills.

Decay is not destruction conditioned reflexes. A faded reflex can be quickly restored by repeated reinforcement. As regards well-strengthened and then quenched reflections, the facts of their spontaneous recovery are known. The positive value of extinction is that it cancels those temporary connections in the cortex that turned out to be unnecessary in the future, which makes it possible to replace them with others.

At a certain stimulus, at first, other homogeneous stimuli also cause a positive reaction, although their action is not combined with an unconditioned stimulus. So, when a dog develops a conditioned salivary reflex to a tone of a certain pitch, at first saliva flows to other tones. This phenomenon is called generalization. However, if the main tone is systematically reinforced with an unconditioned stimulus, and a similar sound (or sounds) is systematically left without reinforcement, then differentiation occurs, the distinction between these sounds: a reinforced tone will cause a positive reflex (excitation), and an unreinforced tone will cause a negative reflex (inhibition). It has been established that the greater the similarity between homogeneous stimuli, the more difficult their differentiation is. Its education requires a large number of repetitions of experience.

Differential braking

Together with some other physiological mechanisms, it underlies all kinds of discrimination, analysis both in animals and in humans: discrimination of sounds, colors, smells, shapes and sizes of objects, movements. In addition, a person has the distinction of words, concepts, thoughts, actions.

Under natural conditions, a young animal at the beginning of its life performs many actions that are not justified by the situation, weakly distinguishing similar objects and influences. Then, gradually, generalized reactions are replaced by more accurate differentiated reactions based on a finer distinction between objects and phenomena. outside world. “Although the owner feeds the puppy, he runs up to strangers. They put him in a box with a soft bedding, and he climbs onto the bed. Having put a sparrow to flight, he begins to chase chickens around the yard ... ”Not so with an adult dog. She subtly distinguishes even the intonations of her master's voice. “Having heard gentle notes, she runs up to him, and when irritation sounds in the owner’s voice, she goes away” (A. B. Kogan). Children starting to study at school, at first, do not distinguish similar sounds of speech - voiced and deaf, hard and soft consonants, so some children say “teeth” instead of the word “teeth”, “suba” instead of “fur coat”, etc. They confuse and letters, numbers, grammatical and arithmetic signs, geometric shapes. While mastering scientific concepts, rules, laws in the process of learning, students often confuse similar things either by verbal expression (for example, the source and tributary of the river, participle and gerund, repression and depression) or by content (for example, strength and tension electric current; weight and body weight; metaphor and comparison; bisector and median; monsoons and trade winds). Sometimes a large number of specially selected exercises are required to teach students to accurately distinguish between similar concepts, rules, laws, etc.

During the experimental formation of a conditioned reflex

Usually during experimental the formation of a conditioned reflex the conditioned stimulus is given 1-5 seconds before the onset of the action of the unconditioned stimulus, then both stimuli act together. However, if gradually from experience to experience we increase the time interval between the isolated action of the conditioned stimulus and the joint action of both stimuli, then an interesting result can be observed. After several repetitions of the experiment, the conditioned stimulus (for example, light) will cause an inhibitory process for some time, and the conditioned reflex will appear with a delay. This is the inhibition of delay. And the longer the time of the isolated action of the conditioned stimulus during the development of the conditioned reflex, the longer the process of inhibition will be. Biologically, this is very expedient: the conditioned response is timed exactly at the time when it should occur in response to reinforcement.

In animals, retardation inhibition lasts within 1 to 3 minutes of the isolated action of the conditioned stimulus. Conditioned reflexes obtained in this way are called delayed. And if the unconditioned stimulus is given only after the cessation of the conditioned stimulus and there is no coincidence, then a trace conditioned reflex is formed. A conditioned reaction does not arise to a present stimulus, but to a trace from it.

Lag braking is the physiological basis of various delayed reactions, which play an important role in the adaptive activity of animals and in the practical activity of people. Not every planned action can be immediately implemented. Sometimes it is necessary to delay the action until a certain time, to have patience, endurance. One of the physiological mechanisms of delayed reactions is the inhibition of delay at the level of secondary signal connections.

Delay inhibition is developed with great difficulty in excitable individuals.

It has also been established that the stronger the conditioned stimulus, the more difficult lag inhibition is generated. It is well known how difficult it is for a small child to restrain himself not to take a delicacy in front of his eyes until the moment when the elders allow, for example, before the end of dinner. The sight of a juicy apple or a sweet cake is a very strong conditioned stimulus. It is easier for the child if the treat is removed for the time being. Inhibition of delay also occurs with difficulty with a strong unconditioned stimulus. It is difficult for a hungry person to wait for the set time for lunch. Prolonged exercise in developing the inhibition of retardation facilitates its occurrence.

If a conditioned stimulus, to which a positive conditioned reflex has been developed, to give simultaneously with some other additional stimulus and this combination is not reinforced, then conditioned inhibition occurs. The role of the conditioned brake here belongs to an additional stimulus.

So, a dog has developed a positive conditioned reflex to the sound of a metronome of a certain frequency. If then gurgling is added to the beat of the metronome and this combination of two stimuli is not reinforced by an unconditioned reflex, then conditioned inhibition will occur (in the narrow sense of the word). The beat of a metronome given under new conditions (together with gurgling) temporarily loses its signal value, and the conditioned reflex to it is inhibited. An additional irritant - gurgling - acts as a conditioned brake.

Any external agent can become a conditioned brake to signal stimuli.

Thus, the slightest change in environment changes the signal role of the conditioned stimulus, which indicates the finest adaptation of the organism to the conditions of its existence.

Here example of natural conditional inhibition. The sniffer dog is taught to take food only from the hands of its owner and does not touch it if someone else feeds it: the sight and smell of food cease to be a conditioned stimulus in other conditions. The role of a conditional brake here is played by the sight and smell of an outsider.

While raising children, we instill in them the skills and abilities to change their behavior depending on specific conditions, to temporarily delay those actions that are considered inappropriate in a certain situation. One of the physiological mechanisms of such delayed responses is conditioned inhibition. It is useful to know that stimuli acting as a conditional brake can have a negative effect on a person, reduce his performance. So, if an inexperienced teacher once greatly frightened a child with a cry or a threat of punishment, then the student subsequently cannot work calmly and productively for a long time: the appearance and voice of the teacher become a conditional brake for him.

Any kind of internal inhibition is an active process of delay, suppression of conditioned reflexes.

It is easy to verify this if at the moment internal inhibition to act on the animal with a stimulus foreign to experience, which under other conditions is an external brake. External inhibition meets internal and disinhibition occurs: the signal stimulus again causes a temporarily delayed conditioned reflex.

Partial braking the cortex can go into general inhibition, sleep. This process has three phases: leveling, paradoxical and ultraparadoxical. In the equalizing phase, strong stimuli are equalized in their action with weak ones. In the paradoxical phase, strong stimuli have less effect than weak stimuli. In the ultraparadoxical phase irritants, which previously caused a positive reaction of the body, now do not cause it at all, and the stimuli that caused an inhibitory reaction now give a positive one.