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 character 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.

26. The principle of feedback and its significance.

The process of self-regulation constantly retains a cyclical nature and is carried out on the basis of the "golden rule": any deviation from the constant level of any vital factor serves as an impetus for the immediate mobilization of apparatuses that restore this constant level again.

By its nature, physiological self-regulation is an automatic process. The factors that deviate the constant and the forces that restore it are always in certain quantitative ratios. In this, physiological self-regulation is closely related to the patterns formulated by cybernetics, the theoretical core of which is the automatic regulation of a given factor using a closed loop with feedback. The presence of feedback reduces the impact of changes in the parameters of the system on its operation as a whole, also ensures its stabilization and stability, improves transient processes, and increases its noise immunity by reducing the influence of interference.

The connection of the output of the system with its input through an amplifying link with a positive gain is positive feedback, with a negative gain - negative feedback. Positive feedback increases the gain and provides the ability to control significant energy flows, while consuming small energy resources. Note, however, that in biological systems, positive feedback is realized mainly in pathological situations. Negative feedback usually improves the stability of the system, i.e., its ability to return to its original state after the cessation of the influence of an external disturbance.

The requirement of stability is one of the main requirements for a control system, since stability usually determines the performance of the entire system.

Feedbacks in the body are usually hierarchical, superimposed on one another and duplicate each other. They can be divided into different categories, for example, by time constant - into fast-acting nervous and slower humoral, etc. For example, the same blood sugar regulation system should be considered as a multi-circuit one. The operation of individual closed circuits of this system is based on a principle that is essentially similar to the principle of operation of the corresponding technical systems. In a permanently closed control loop, the current deviations of the vegetative quantity to be controlled from its set value are measured all the time, and on the basis of this information, the center controlling the executive bodies performs such a restructuring, as a result of which the resulting deviations of the controlled quantity are eliminated.

In the 30s. Soviet biologist M. M. Zavadovsky, based on the study of humoral mechanisms of regulation in a growing organism, put forward the general biological principle of regulation of developmental processes and homeostasis "plus - minus interaction." The essence of this concept is as follows. If there is a direct connection between two organs (processes), and the first organ (process) stimulates the second, then the second inhibits the first, and vice versa. Basically, it is a feedback mechanism. At the same time, we mean such forms of interaction when direct and feedback links between organs and processes have opposite signs: plus - minus, minus - plus. This type of connection provides the animal and man with the properties of a self-regulating system with a high degree of stability.

In the course of studying the role of afferent information in the implementation of locomotor acts, N. A. Bernshtein put forward the idea of ​​sensory corrections, according to which the continuous participation of the flow of afferent signaling of a control or correction value is a necessary component of motor reactions. Each case of an ordered response is a continuous cyclical process of the organism's interaction with the changing conditions of the environment or internal environment. At the same time, controlling corrective afferentation plays a huge role.

Another Soviet physiologist, P.K. Anokhin, back in the 30s. and, perhaps, for the first time clearly substantiated the concept of reverse, or sanctioning, afferentation, i.e., mandatory for any action of impulsation that comes from receptors in the central nervous system and informs about the results of the action performed, corresponding or not corresponding to the intended goal. With further development of the mechanism, the latter was called the acceptor of the result of the action.

Examples of the implementation of feedback in the body are countless. Let us consider only some of the processes of regulation in the nervous system. The distribution of nervous influences is vaguely reminiscent of railway traffic from one station to another. The freight turnover of a station is mainly determined not by its size, the number of warehouses, etc., but by the density and capacity of its communication lines with other stations. Similarly, in the nervous system, the emphasis in regulation is often placed on the precellular link - the synaptic apparatus. Like semaphores and arrows, in front of which movement often stops, presynaptic regulation is carried out in the nervous system. Its essence lies in the fact that excitation impulses running along one fiber, thanks to a specialized intermediate neuron, make it difficult for the same impulses to propagate along other nerve fibers and "the train stops in front of a semaphore."

In the central nervous system, there is another type of regulation, perhaps the most studied, carried out at the output of the reflex arc - recurrent inhibition. In this case, the impulses propagating from the motor cell to the muscles partially return to the spinal cord and through a specialized intermediate neuron - the Renshaw cell - reduce the activity of the same or other motor neurons, desynchronizing their activity. As a result, muscle fibers do not contract simultaneously, which ensures smooth muscle movements. The example with motor neurons of the spinal cord is perhaps the most striking, but in general, such methods of self-regulation of reflex activity by the type of negative feedback are widespread in the central nervous system.

The value of feedback mechanisms in maintaining homeostasis is extremely high. Thus, maintaining a constant level of blood pressure is always the result of the interaction of two forces: one that violates this level and one that restores it. As a result of increased impulses from the baroreceptor areas (mainly the carotid sinus zone), the tone of the vasomotor sympathetic nerves decreases and high blood pressure normalizes (see also sections 5.4; 8.6). Depressor reactions are normally stronger than pressor reactions. An increase in the content of catecholamines in the blood - adrenaline and noradrenaline - when they are injected or during the natural reaction of the body to external influences, leads to the activation of peripheral effector formations, thereby simulating the excitation of the sympathetic department of the nervous system, but at the same time reduces sympathicotonus and prevents further release and synthesis of these compounds .

27. The concept of the types of the nervous system.

The type of the nervous system is a set of processes occurring in the cerebral cortex. It depends on the genetic predisposition and may vary slightly over the course of an individual's life. The main properties of the nervous process are balance, mobility, strength.

Balance is characterized by the same intensity of the processes of excitation and inhibition in the central nervous system.

Mobility is determined by the rate at which one process is replaced by another. Strength depends on the ability to respond adequately to both strong and super-strong stimuli.

According to the intensity of these processes, IP Pavlov identified four types of the nervous system, two of which he called extreme due to weak nervous processes, and two - central.

People with type I nervous system (melancholic) are cowardly, tearful, attach great importance to any trifle, pay increased attention to difficulties. This is the inhibitory type of the nervous system. Type II individuals are characterized by aggressive and emotional behavior, rapid mood swings. They are dominated by strong and unbalanced processes, according to Hippocrates - choleric. Sanguine people - type III - are confident leaders, they are energetic and enterprising.

Their nervous processes are strong, mobile and balanced. Phlegmatic people - type IV - are quite calm and self-confident, with strong balanced and mobile nervous processes.

The signaling system is a set of conditioned reflex connections of the organism with the environment, which subsequently serves as the basis for the formation of higher nervous activity. According to the time of formation, the first and second signal systems are distinguished. The first signaling system is a complex of reflexes to a specific stimulus, for example, to light, sound, etc. It is carried out due to specific receptors that perceive reality in specific images. In this signaling system, the sense organs play an important role, transmitting excitation to the cerebral cortex, in addition to the brain section of the speech-motor analyzer. The second signal system is formed on the basis of the first one and is a conditioned reflex activity in response to a verbal stimulus. It functions due to speech-motor, auditory and visual analyzers.

The signaling system also affects the type of nervous system. Types of the nervous system:

1) medium type (there is the same severity);

2) artistic (the first signal system prevails);

3) thinking (the second signal system is developed);

4) artistic and mental (both signal systems are simultaneously expressed).

28. properties of nervous processes.

The properties of nervous processes are understood to mean such characteristics of excitation and inhibition as the strength, balance and mobility of these processes.

The power of nervous processes. When measuring the strength of the excitation process, the curve of dependence of the magnitude of the conditioned reaction on the strength of the stimulus is usually used. The conditioned response stops increasing at a certain intensity of the conditioned signal. This boundary characterizes the strength of the excitation process. An indicator of the strength of the inhibitory process is the persistence of inhibitory conditioned reflexes, as well as the speed and strength of the development of differential and delayed types of inhibition.

Balance of nervous processes. To determine the balance of nervous processes, the forces of the processes of excitation and inhibition in a given animal are compared. If both processes mutually compensate each other, then they are balanced, and if not, then, for example, during the development of differentiations, a breakdown of the inhibitory process can be observed if it turns out to be weak. If the inhibitory process dominates due to insufficient excitation, then under difficult conditions, differentiation is preserved, but the magnitude of the reaction to a positive conditioned signal decreases sharply.

Mobility of nervous processes. It can be judged by the rate at which positive conditioned reflexes are converted into inhibitory ones and vice versa. Often, a modification of the dynamic stereotype is used to determine the mobility of nervous processes. If the transition from a positive reaction to an inhibitory reaction and from an inhibitory reaction to a positive one occurs quickly, then this indicates a high mobility of the nervous processes.

29. The doctrine of the dominant A.A. Ukhtomsky.

Dominant- a stable focus of increased excitability of the nerve centers, in which excitations coming to the center serve to increase excitation in the focus, while in the rest of the nervous system, inhibition phenomena are widely observed.

The external expression of the dominant is a stationary supported work or working posture of the body. For example, the dominant of sexual arousal in a cat isolated from males during estrus. A variety of irritations, whether it be the sound of plates, a call for a cup of food, etc., now cause not the usual meowing and begging for food, but only an increase in the estrus symptom complex. Even the introduction of large doses of bromine preparations is unable to erase this sexual dominant in the center. The state of severe fatigue also does not destroy it.

The role of the nerve center, with which it enters into the common work of its neighbors, can change significantly, from excitatory it can become inhibitory for the same devices, depending on the state experienced by the center at a given moment. Excitation and inhibition are only variable states of the center depending on the conditions of stimulation, on the frequency and strength of the impulses coming to it. But various degrees of excitatory and inhibitory influences of the center on the organs determine its role in the body. Then the conclusion follows from this that the normal role of the center in the organism is not its invariable, statistically constant and only quality, but one of its possible states. In other states, the same center may acquire a significantly different significance in the overall economy of the organism.

In the normal activity of the central nervous system, the current variables of its task in an incessantly changing environment cause in it variable "dominant centers of excitation", and these centers of excitation, diverting the newly emerging waves of excitation to themselves and slowing down other central devices, can significantly diversify the work of the centers.

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, the 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 has been found that orienting reflexes not only inhibit the formation of conditioned reflexes, but are also a necessary condition for their formation. Any stimulus at the beginning of its action causes an orientation 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 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, the individual characteristics of people, the type of their higher nervous activity are important.

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 mastering 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. For its formation, a large number of repetitions of experience is required.

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 more subtle distinction between objects and phenomena of the external 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 a river, participle and gerund, repression and depression) or by content (for example, the strength and voltage of an electric current; weight and mass bodies; 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 the environment changes the signal role of the conditioned stimulus, which indicates the subtlest 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 with 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.

Pavlov identified two types of external and internal.

External (unconditional) inhibition is an innate property of the nervous system associated with the weakening or cessation of behavioral stimuli under the action of stimuli from the external environment. Unconditional braking characteristic of all parts of the nervous system, it does not need to be developed, it appears simultaneously with the onset of the orienting-exploratory, caused by an outsider new, and manifests itself in the weakening or oppression of others. Unconditional (innate) inhibition of SD is also called external, since the cause of its occurrence is outside the reflex arc of the inhibited reflex.

External braking mechanism: an extraneous signal is accompanied by the appearance in the cerebral cortex of a new focus of excitation, which, with an average strength of the stimulus, has a depressing effect on the current conditioned reflex activity by the dominant mechanism. External inhibition contributes to the emergency adaptation of the body to changing conditions of the external and internal environment and makes it possible, if necessary, to switch to another activity in accordance with the situation.

Biological significance of external inhibition the current conditioned reflex activity is reduced to the creation of the most favorable conditions for the flow of the orienting-exploratory reflex, which is more important for the organism at the moment, caused by an emergency stimulus. Conditions are created for an urgent assessment of a new stimulus, for assessing its significance for the organism at a given moment and under given conditions. This is where the most important coordinating, ordering adaptive role of external inhibition in . This type of inhibition is based on negative induction (excitation in a new center causes inhibition in the former one).

There are two main types of unconditional inhibition:

Extinguishing brake , it is connected with the fact that conditioned reflex reactions are inhibited under the action of extraneous stimuli, under the influence of which both conditioned reflex and unconditional reflex reactions arise. In most cases, an orienting reaction occurs, which gradually fades with repeated action. EXAMPLE : A person constantly experiences the effect of a dying brake. The first knock on the door causes an indicative reaction that distracts the working person from his main occupation. But if you repeat this several times, then with each new knock on the door, its irritating effect weakens and, finally, completely disappears. In the life situation of schoolchildren, such a brake also occurs. A student in a new classroom may for some time “forget” the educational material well known to him. But as soon as he “looks around”, he disappears, and new conditions cease to be a hindrance to him. Therefore, it is very important that children who begin school life or continue it in new conditions have some time to look around and get used to these conditions, so that new conditions (orienting reactions to the situation, to the appearance of the teacher, etc.) do not interfere them to learn a lesson.

Permanent brake – this is such an additional stimulus that does not lose its inhibitory effect with repetition. This braking is called induction, because. its mechanism is based on negative induction and , and is constant because it always manifests itself, not weakening when it is repeated. A constant brake is important for the body, and therefore requires a person to take decisive measures to eliminate it, therefore, conditioned reflex activity is inhibited. EXAMPLE : . In a person with acute toothache, a small wound on the arm stops hurting, i.e. a stronger pain excitation suppresses a less strong one.

The same applies to unconditional inhibition. Extreme braking , which is based on persistent depolarization of the membrane, leading to the closure of sodium channels. develops with prolonged nervous excitation of the body, protecting against exhaustion, the activity of nerve cells is temporarily turned off, which creates a condition for normal excitability and performance. The main signs of this inhibition are: lethargy, drowsiness, twilight state, loss of consciousness, the extreme option is a state of stupor.

The physiological basis of this inhibition is the irradiation of inhibition through the cerebral cortex and part of the sequential induction (self-induction), in which the process of excitation is mostly replaced by inhibition, and inhibition covers large areas of the brain. Extreme inhibition itself is the physiological basis of distraction and the second (“inhibitory”) phase of student fatigue in the lesson. For the occurrence of this inhibition, the following conditions are necessary: ​​1) the action of an ordinary stimulus for a long time; 2) the action of a stimulus of great strength for a short time.

Limiting inhibition develops during prolonged nervous excitation of the body and under the action of an extremely strong conditioned signal or several weak ones, the strength of which is summed up. In this case, the “law of force” is violated (the stronger the conditioned signal, the stronger the conditioned reflex reaction) - the conditioned reflex reaction begins to decrease with increasing force. This is because cells have a certain limit of efficiency, and stimulation above this limit turns off neurons, thereby protecting them from exhaustion.

This inhibition has a protective value, since it prevents the debilitating effect on the nerve cells of excessively strong and prolonged irritation and protects the cells of the cerebral cortex from exhaustion and destruction. This property indicates that the cells of the cerebral cortex have the ability to protect themselves always and especially when the demands made by irritation cease to correspond to their performance. With excessive irritation or with the usual, but prolonged, in the cells of the brain there is an outrageous inhibition. EXAMPLE : In training, when you do an exercise for a long time, then you can no longer do it. O Asking students after long and tiring classes leads to the fact that gradually each new question, instead of an active reaction, will cause oppression. In this state, the child soon ceases to answer even those questions that at the beginning of the lessons did not cause him any difficulties. The biological significance of such a reaction comes down to providing depleted brain cells with the necessary rest for subsequent vigorous activity.

Interaction of different types of internal inhibition. Different types of inhibition interact with each other. Two main types of interaction:

disinhibition – one inhibitory process destroys the other. The disinhibition of the inhibited reflex is created by an agent foreign to it and ends with the termination of its action. The release depends on the strength of the external brake. If the external brake is weak, then it leaves the UR unchanged. If the external brake is very strong, then all SDs are completely delayed. With an intermediate force of a conditional brake, the following variants of the result exist:

a) since the release depends on the strength of the developed internal braking, the stronger the internal braking of the SD is developed, the more difficult it is to release it;

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 it, 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 cerebral cortex increases, which is associated with a weakening of the process of internal active inhibition. In the future, these normal force relationships change (phase states arise) and inhibition develops.

What is braking for?

If for some reason the vital significance of some conditioned stimulus is lost, inhibition cancels its action. 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. The internal form includes 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

Transboundary inhibition 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 says that the stronger the conditioned signal, the stronger the reflex arc. 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 is concentrating to overcome danger, and is therefore 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 emergence 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 first causes him an indicative reaction "who is 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 transboundary 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 inhibition replaced the excitation. 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. In schoolchildren, such inhibition occurs in the lesson when the teacher explains the educational material from the very beginning in a too loud voice.

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 the person's response to the strongest external or internal stimulus at a given time, whether it be 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 a real opportunity to save or restore ... ... Encyclopedic Dictionary of 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- a kind of 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