What is dominant in biology. Dominants. The doctrine of the dominant and constellation of nerve centers

The very first observation that formed the basis of the concept of dominant was made by Ukhtomsky in 1904:

It consisted in the fact that in a dog, during the period of preparation for defecation, electrical stimulation of the cerebral cortex does not give the usual reactions in the limbs, but increases excitation in the defecation apparatus and contributes to the onset of a permissive act in it. But as soon as defecation is completed, electrical stimulation of the cortex begins to cause the usual movements of the limbs.

Ukhtomsky A. A. Dominant and integral image. - 1924.

However, Ukhtomsky did not publish information about the dominant for more than a decade, until 1922, when he made a report on the dominant. In he publishes the work "Dominant as a working principle nerve centers»; then the principle of dominance is discussed by him in many other later works. Ukhtomsky borrowed the word "dominant" from Richard Avenarius' Critique of Pure Experience.

Dominant principle

At all moments of life, conditions are created under which the performance of any function becomes more important than the performance of other functions. Executing this function overrides other functions.

One of clear examples dominants can be called the dominant of sexual arousal in a cat isolated from males during estrus. Various stimuli (the call for a bowl of food, the clatter of plates on the table) cause in this case not meowing and a lively begging for food, but only an increase in the estrus symptom complex. The introduction of even large doses of bromine preparations is unable to erase this sexual dominant in the centers.

The doctrine of the dominant and constellation of nerve centers

The dominant, according to Ukhtomsky, is a complex of certain symptoms throughout the body - both in the muscles, and in secretory work, and in vascular activity. It does not appear as a topographically single point of excitation in the central nervous system, but as "certain constellation of centers with increased excitability in various floors of the brain and spinal cord, as well as in the autonomous system.

The role of the nerve center can change significantly: from excitatory to inhibitory for the same devices, depending on the state experienced by the nerve center in this moment. IN different situations nerve center can acquire different meaning in the physiology of the body. “Newly coming waves of excitation in the centers will go in the direction of the currently dominant focus of excitation.”

Ukhtomsky believed that the dominant is capable of transforming into any "individual mental content." However, the dominant is not the prerogative of the cerebral cortex, it is common property throughout the central nervous system. He saw the difference between "higher" and "lower" dominants. The "lower" dominants are of a physiological nature, the "higher" ones - arising in the cerebral cortex - form the physiological basis of the "act of attention and objective thinking".

Numerous studies, conducted by Ukhtomsky, his colleagues and independent scientists testified that the dominant plays the role of the general working principle of the nerve centers.

For Ukhtomsky, the dominant was what determines the direction of human perception. The dominant served as the very factor that integrates sensations into the whole picture (here you can draw a parallel with gestalt). Ukhtomsky believed that all industries human experience, including

DOMINANT(lat. dominans, dominant dominant) - a focus of excitation in the central nervous system, directing the integral activity of the body at a given moment and under given conditions.

D. is a special state of the nerve centers (see. Centers of the nervous system), characterized by increased excitability, persistence and inertia of the emerging process of excitation, that is, the ability to retain and continue the excitation that has begun once. This D.'s property can lead to emergence in c. n. With. "stagnant" focus of excitation, capable of causing a functional disorder of mental activity.

The appearance of a "stagnant" focus of excitation as a result of repeated negative emotional influences can be the cause of a number of diseases, such as hypertension, angina pectoris, peptic ulcer, etc.

The dominant center (center) is a set of structures of c. n. With. with selectively increased excitability, capable of summing up excitations and forming a certain reflex activity of the body when any irritation is applied, regardless of its origin and quality. Methods have been developed for the artificial creation of a dominant center, for example, by means of an anode polarization of a weak direct current or application pharmakol, substances (strychnine, etc.) on various areas cortex and subcortical structures.

The doctrine of D. was developed by A. A. Ukhtomsky. The doctrine was based on the following fact: in a dog preparing for defecation, irritation of a section of the motor area of ​​the cerebral cortex caused a full-fledged act of defecation instead of motor reactions of the limbs. The act of defecation is prepared by a continuous stream of afferent impulses from the receptors of the rectum to the nerve centers, which leads to an increase in their excitability. Under these conditions, the excitation of the centers of defecation increases already under the influence of impulses entering the c. n. With. regardless of the location and quality of irritation. An increase in excitability in the nerve centers and the formation of D. can be caused not only by afferent impulses, but also by hormonal influences. So, in male frogs in spring period in connection with the increase in the level of sex hormones, a strong "hugging reflex" is observed; due to the contraction of the flexors of the forelimbs, the male firmly grasps the female, holding her in this position during the entire period of spawning. The application of irritation to the surface of the body of the male, instead of causing the corresponding defensive reflex, increases the tension of the muscles of the flexors of the forelimbs.

D.'s discovery showed that the end result of the body's reflex reaction is not entirely determined by the conduction of impulses from receptors to effector organs along isolated paths according to the classical ideas about reflex arcs, but largely depends on the functional state of the nerve centers.

Under the conditions of D., the emerging focus of excitation inhibits all other reflexes to the next stimuli, subjugates the activity of other centers and represents the dominant system of connections in the body that unites the nervous elements. various levels c. n. With. and peripheral organs.

Under natural conditions, it is not the focus of excitation that dominates, but one or another functional system (see Functional systems), which ensures the achievement of an adaptive result useful for the body.

In the body, D. arises on the basis of the motivational excitation that is dominant at the moment (see Motivations). In this regard, food, sexual, defensive and other types of D are isolated. During pregnancy, a change in all functions in a woman's body is aimed at successful bearing of the fetus.

This orientation is associated with the formation of pregnancy in the body of D., which obeys the laws characteristic of D. Such a D. is formed in connection with the occurrence of interoceptive impulses from the uterus, a change in the activity of the endocrine glands, the appearance of the placenta, the action of fetal metabolic products, etc.

Neurofisiol, the mechanism that forms D., is an ascending activating influence of the centers of the hypothalamus and the reticular formation of the brain, selectively increasing the level of excitation in certain cells of the cerebral cortex of the cerebral hemispheres, increasing their excitability and increasing the volume of convergence of excitation different quality. In turn, the descending influences of certain areas of the cerebral cortex selectively facilitate the conduction of excitation through the relay nuclei of the thalamus and the reticular formation. Under these conditions, almost any stimulus causes a summation of excitation processes in the corresponding nerve centers and leads to the organization of a holistic activity that ensures the achievement of a useful result by the body. D.'s mechanism takes part in the formation of the initial stage of the central architecture of any functional system - the stage of afferent synthesis (see).

The doctrine of D. reveals a universal pattern in the activity of the whole organism. The mental activity of a person is subject to the principle of D.; once having arisen, D. is able to form an active purposeful behavior and be a driving factor mental development, moral and ethical motives.

Bibliography: Anokhin P. K. Internal inhibition as a problem of physiology, M., 1958, bibliogr.; it, Biology and neurophysiology of a conditioned reflex, M., 1968, bibliogr.; Arshavsky I. A. Pregnancy dominant and the problem of physiologically complete ontogenesis, Proceedings of Nauch. un-ta, vol. 24, p. 161, 1956; Konradi G. P. Transition of dominant into inhibition, Collection of works of fiziol. laboratories Leningradr, un-ta, p. 118, M. - L., 1930; Rusinov V.S. Dominant, M., 1969, bibliography; Sudakov K. V. Biological motivations, M., 1971; he, Dominant motivation as the basis of purposeful activity, in the book: Sensory organization of movements, ed. A. S. Batueva, p. 204, L., 1975, bibliogr.; Ukhtomsky A. A. Collected works, vol. 1, p. 31, L., 1950.

S. A. Osipovsky.

(from lat. dominans, genus. case dominantis - dominant) (physiol.), the predominant (dominant) system of interconnected nerve centers, temporarily determining the nature of the body's response to any external. or int. irritants. Main provisions of the doctrine about D., as general principle the work of the nerve centers, formulated by A. A. Ukhtomsky in 1911-1923. He put forward the idea of ​​\u200b\u200bthe "dominant central constellation" that creates the hidden readiness of the body to determine. activity with simultaneous inhibition of extraneous reflex acts. D. arises on the basis of the prevailing motivational excitation. In this regard, food, sexual, defensive, and other types of D. are isolated. in order to cause the corresponding defens, reflex, increases the tension of the flexor muscles of the forelimbs. D. as a vector of behavior serves fiziol. the basis of a number of complex mental. phenomena.

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