Disruptions of higher nervous activity in animals, Forms of...

Disruptions of higher nervous activity in animals

The presentation of an impossible task to an animal, both in the laboratory environment and in its natural habitat, can cause him to disrupt the higher nervous activity (neurosis) , which manifests itself in various deviations of conditioned reflex activity. In fact, neurosis is a condition based on a violation of the strength, mobility and balance of the basic nervous processes: excitation and inhibition. Most often, these conditions occur due to overstrain of the central nervous system, which can be caused by various causes.

The disruption of higher nervous activity can be either ongoing or very deep and prolonged, and even accompanied by trophic disturbances in many systems and organs.

Forms of manifestations of neuroses

Neuroses in animals manifest themselves in three main forms:

1) excitation;

2) braking;

3) phobias.

Neurosis in the form of excitation manifests itself in a sharp increase in excitability, differentiation is disrupted, the animal is not able to inhibit its conditioned reflexes. In this case, conditioned reflexes can be of considerable magnitude, but differentiations, as a rule, are violated. Chaotic motor excitability is observed, increased salivation can be observed.

Neurosis in the form of inhibition is manifested in the fact that the whole conditioned reflex activity is completely or almost completely absent, the animal becomes sluggish, inhibited.

Neurosis in the form of a phobia can be defined as an obsessive experience of fears in a particular setting. There are specific behavioral manifestations, the purpose of which is to avoid the object of fear, including the environment associated with it, or reduce fear through obsessive actions.

The causes of neuroses. Most often, neuroses develop as a result of the overstrain of the excitatory process, which can arise as a result of the action of strong stimuli on the psyche of the animal.

Overexertion of this process with the subsequent development of neurosis in Pavlov's laboratory was observed in the following cases.

In the experiment, the dogs developed a positive reflex to a negative conditioned stimulus, i.e. food reinforcement the dog received after applying irritation by electric current. At first the current was weak, but it was gradually strengthened. Despite the high current strength, the dogs underwent conditional salivation. However, when electrodes were applied to the most sensitive parts of the body, the dogs developed a breakdown in nervous activity. Now even the weakest current began to cause them a violent defensive reaction. All conditionally reflex activity of dogs was disturbed for a long time. In this case, too strong a conditioned stimulus led to the development of a neurosis.

Neurosis can develop and under the influence of strong stimuli, which cause an unconditioned reflex reaction. The emergence of neuroses in a certain traumatic the situation is characterized by a very rapid formation of "pathological"

conditioned reflexes, probably by the type of dominant binding the state of the organism to individual environmental stimuli or a combination of them. A very characteristic example of this is the neurosis, which was the consequence of the flood of 1924 in Leningrad, during which the premises were flooded, in which the experimental dogs of Pavlov and his collaborators were located. The dogs had to be dragged out with great difficulty from the cells flooded with water, through the flooded doors, immersing them for this purpose in the water entirely. This super-strong effect caused a considerable shock in the nervous system in dogs, as a result of which a neurosis developed in some of them, which affected the conditioned reflex activity of dogs. It took weeks for the conditioned reflex activity of the dogs to return to normal. But even then, when the conditioned reflexes were restored, it was worthwhile to put a stream of water under the door of the chamber where they worked with the dog, as it again violated conditioned reflex activity.

From the point of view of the physiology of higher nervous activity, excessively strong stimuli cause in the nerve cells an excitatory process of excessive intensity, which leads to its overexertion.

The term superstrong stimulus does not imply any definite physical strength, but only the fact that this force exceeds the ability of nerve cells to respond to it with the appropriate maximum excitation. If the CNS cells are weakened (fatigue, illness or other causes), even a normal moderate-power stimulus can be super-strong. Therefore, systematic exhaustion, hard work without rest in difficult conditions can cause the so-called neurosis of exhaustion. In this case, there is a periodicity in the performance of the central nervous system - conditioned reflexes then appear, then disappear.

The cause of neurosis development can also be overstrain of the inhibitory process, which can occur for the following reasons:

• when differentiated (similar) stimuli are differentiated;

• when delaying the action of negative stimuli;

• with a long delay of reinforcement.

Delay of reinforcement for an indefinite time and waiting for negative reinforcement are very unfavorable. For some animals, the greatest difficulty is the development of internal inhibition. Overstrain of the inhibitory process and breakdowns of higher nervous activity can be caused by: lengthening the duration of action of inhibitory stimuli, developing delayed inhibition in a system of short-delayed reflexes, summing up various forms of internal inhibition, and the formation of subtle and complex differentiations. For example, prolongation of the action of the differentiating stimulus leads to a stress of the inhibitory process, causing a prolonged disruption, which is manifested in a sharp chaotic excitation, in the development of various deviations in the behavior of the animal, the appearance of any phobias (fears).

Disruption of inhibition can be obtained from an animal when presented with tasks related to difficult and subtle differentiation.

Thus, in experiments carried out at the Pavlov Laboratory (1921), long-term disturbances of higher nervous activity were obtained by establishing the limit of differentiation of visual stimuli. Initially, the dog developed a rough differentiation of the circle from the ellipse with a ratio of semiaxes of 2: 1. Gradually bringing the shape of the ellipse closer to the shape of the circle, it was possible to work out the differentiation of the circle from the ellipse with the ratio of the semiaxes 9: 8. However, the attempt to strengthen this differentiation led to a violation of the discrepancy between the circle and the ellipse even with the ratio of the semi-axes 2: 1. The general behavior of the dog also changed: it barked, squealed, ripped off the capsule to register saliva, gnawed rubber tubes, and the like.

Neuroses, arising as a result of fine differentiation, turn out to be very persistent, so, in the experiment described above, conditioned reflex activity of the animal was restored only after a two-month break in work. Differentiation could be worked out again only with the gradual training of the inhibition process by applying simpler inhibitory stimuli.

Overvoltage of the mobility of nerve centers occurs with a rapid change in the inhibitory stimulus positive or vice versa. Such a busting processes of excitation and inhibition can also lead to the development of neurosis. Overvoltage of the mobility of the nervous processes can occur when the cells of the cerebral hemispheres are forced to move too quickly from the excited state to the inhibitory state and vice versa. Reorganization of the functional state of nerve cells requires a certain amount of time and training. Attempts to forcibly accelerate such a restructuring can lead to serious violations of the function, which is manifested in the disruption of mobility, which can occur in the following cases:

• with an emergency feedback of the signal value of conditioned stimuli;

• when the excitatory and inhibitory processes are disrupted by calling one of them before the other is completed (positive and negative conditioned stimuli are fed one by one without interruption);

• When breaking a firmly established stereotype of stimuli.

In conditions of weakening cells in the large hemispheres in experimental dogs, it was possible to cause neuroses by a sharp change in the stereotype of stimuli that is habitual for them. Unable to such a rapid restructuring of their functional state, the cortical cells lost their normal mobility, which led to the development of a neurosis.

Neurosis as a result of the collision was first obtained on a dog in which the inhibitory stimulus (12 touches to the skin for 30 seconds) was directly replaced by the application of a positive stimulus (24 touches to the skin for 30 seconds). This led to a prolonged deviation of the dog's behavior from the norm with a complete or almost complete absence of conditioned reflexes (breakdown in the direction of inhibition). Abnormal conditioned reflex activity was observed in her for a total of five weeks.

Describes the neuroses arising when conditioned reflexes are elaborated on excessively complex complex stimuli and differentiations to them, on the use of stimuli with probabilistic reinforcement (for example, reinforcement of every third or fourth application of stimuli); when elaborating reflexes on the chain of consecutive stimuli or other complex systems of conditional bonds.

Also described are information neuroses - their appearance was clearly shown when overloading the memory of dogs.

The emergence of neuroses in the form of inhibition or phobias was repeatedly noted in animals of different species when they presented logical problems in the process of investigating elementary rational activity. It is interesting to note that the neurotic states in animals were usually manifested on the day after successful solutions to the problems.

The study of experimental neuroses has shown that repeated exposure to extraordinary factors or the creation of conditions that cause neurosis leads in some cases to further disruption of higher nervous activity, in others to its improvement, normalization.

In cases where neurosis occurs due to overstrain of nervous processes, treatment should primarily include providing rest to the nervous system and excluding those stimuli that led to failure.

To prevent neuroses and phobias, first of all, it is necessary to observe the gradualness of the training of the nervous processes: the gradual increase in the complexity of skills, the strength of stimuli, the duration of activities, etc.

With. N. Vyrzhikovsky, F. P. Mayorov and L. V. Krushinsky showed that the absence, especially in early childhood, of the training that the nervous system receives daily in different life situations deprives the animal of the ability to adapt not only to difficult nervous tasks, but also to relatively simple situations (early sensory deprivation).

The gradual complexity of the tasks presented to the nervous system, the alternation of rest and training of nervous processes are the most important principles for improving the work of the brain.

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