From Big Medical Encyclopedia

INSTINCT (Latin instinctus motivation) — the purposeful adaptive activity caused by inborn mechanisms and which is made under the influence of the basic biological needs.

From the evolutionary point of view And. represents «information experience» of the previous generations of this species of animals, useful to an individual (or the person) on satisfaction of the main biol, requirements, imprinted in certain structures of an organism. Historically leading role in implementation of the hereditary information put in the genetic device of cells of an organism was assumed by the nervous system, and in particular the hypothalamic area (at the highest animals and the person) regulating all forms of rhythmic activity of an organism (metabolic processes, growth, development etc.) and defining transformation internal biol, requirements in the behavior directed to their satisfaction (see. Limbic system ). Being expression of hereditary mechanisms of an organism, And. defines bases of his behavior and an ontogeny.

The concept «instinct» was applied for the first time by the Ancient Greek philosopher Hrisipp to the characteristic of behavior of birds and other animals. The fr. thinker and the doctor Zh. Lametri laid the foundation for the scientific analysis And., having connected this phenomenon with the corporal organization of animals, with a structure of their nervous system and having noticed its automatic character. The fr. scientist Zh. Kyuvye emphasized such features And., as innateness and stereotype. Scientists differently explained an origin I. Kondilyak (E. V. to Condillac) characterizes And. as reduction of mind, X. De Rua — as a germ of the last, and Ge. Lamarck — as inheritance of the habits which resulted from satisfaction of the vital requirements. According to Ch. Darwin, there are two sources of formation And. — inheritance of the properties acquired as a result of reasonable activity and also thanks to natural selection of animals, accidentally arisen, useful to this look.

I. M. Sechenov and I. P. Pavlov revealed reflex mechanisms I. According to I. P. Pavlov, And. — it is difficult, unlike simple instinctive reflexes (a blinking, sneezing, cough etc.), an instinctive reflex, i.e. a number of consecutive reflex movements from which everyone previous is an initial push for everyone the subsequent. And. it is quite often just identified with instinctive reflexes, between subjects I. — it not only fiziol., but also the unconscious mental phenomenon, fiziol which mechanism are instinctive reflexes. The huge role in implementation of instinctive activity is played by hemadens. Anatomo-fiziol, substrate of instinctive reactions ripens during various periods of embryonal and postembryonal life of an organism.

For manifestation And. existence of unconditional alarm incentives, napr, sexual is necessary And. birds and mammals wakens at emergence of a complex of ekologo-sexual factors. So, for birds alarm irritants are length of light day, a nested microlandscape, etc.; for mammal (hoofed animals) — a sharp thermocline, emergence of greens, and also individuals of an opposite sex, etc.

Instinctive reactions have reasonable character only at constancy of external conditions. At jump of conditions they become inexpedient (e.g., at deliberate destruction by the person of a bottom of cells in cells of bee continue to fill cells with honey). However against the background of stereotype and banality of instinctive activity plasticity, variability and development takes place. Predetermining a form of behavior, inborn mechanisms at a considerable part of animals do not define an object of this behavior: just hatched baby birds equally peck both grains, and sawdust. The choice of an object is given by individual experience. At the same time in pure form And. it is shown at the highest animals right after the birth; so, at a newborn organism mechanisms of a so-called imprinting (printing, imprinting) turn on by means of which the organism enters initial interaction with the world around. Further instinctive reactions develop in ontogenesis in a combination and interaction to processes of training. And participate in real interaction of an organism and the environment psikhofiziol, mechanisms both the specific, and individually gained experience. At the same time than higher level of development of c. N of page, bigger specific weight in behavior occupy by that the reactions acquired in individual life.

If at insects And. play the leading role, and at mammals in process of increase of level of the organization of c. the N of page the increasing specific weight gains life experience, at the person I. play already subordinated role, being under control of reason and social norms of morality.

Given modern neurophysiology and attempt of modeling of reflex activity showed that the usual scheme of an instinctive reflex (i.e. an incentive — reaction) is insufficient for an explanation for I. Osnov of any And. make internal biol, requirements, and they in turn put in action inborn fiziol, mechanisms of «the main inclinations», or motivations — hunger, fear, sexual excitement, care of posterity, construction of dwellings, etc. (see. Motivations ).

From the point of view of the theory of functional system of P. K. Anokhin, the functional organization I. has the general with the acquired forms of behavior to a very techtonic dance (see. Functional systems ). And. turns on devices afferent synthesis (see), decision-making, statements of the purpose to action, action, achievement of the result satisfying the dominating requirement, and assessment of the achieved result.

Unlike the acquired forms of purposeful activity (see. Purposeful reactions ), central very tectonics And. the hl is based. obr. on inborn mechanisms of motivations, memory, decision-making, statements of the purpose to action, behavior and assessment of its results. At the same time, according to N. Tinbergen, in sale of mechanisms I. also special external — so-called key or releasing, irritants take part.

Any instinctive activity as well as the acquired forms of behavior, is under construction according to the uniform scheme: formation of the corresponding requirement — its satisfaction. In the course of the activity of an organism directed to satisfaction of this or that requirement in c. the N of page occurs assessment of each stage and net result. And in instinctive activity on the basis of inborn mechanisms all chain of results — from intermediate to final and all difficult activity providing their achievement is programmed. At the same time unlike the acquired mechanisms of satisfaction biol, requirements And. it is characterized by rigid programming of the step-by-step results leading to satisfaction of the arisen requirement. In case of lack of stage result (and according to the return afferentation about it) the net result cannot be achieved and the animal does numerous attempts to achieve stage result.

The instinctive activity used from generation to generation for satisfaction of the main inclinations of an organism can be very difficult. Example such difficult And. activities of insects, birds and other animals for getting of food, construction of a nest and removal of posterity, seasonal flights of birds etc. can serve. Nevertheless instinctive activity is always developed on sample type; only to a dlita-nye changes of living conditions can cause in it some shifts.

The instinctive behavior of the highest animals is under construction on the basis of inborn bonds of subcrustal limbic structures with a minimum of the cortical centers (zone orbital and temporal bark). And though participation of a cerebral cortex in instinctive activity is limited, it is a basis for education in individual life of various skills, defining importance And. in formation of century of N of of the person (see. Higher nervous activity ).

On the basis of various And. there is a training in any form. However in the course of training And. gradually pales into insignificance; the leading role passes to external, preferential social, to factors. Education of the person substantially is based in the direction of development of ability to suppress and direct instinctive activity, to date it for a certain place and time.

In the course of individual training the organism accumulates own experience which is under construction on the basis of synthesis of irritations of the inner and outside world (afferent synthesis, according to P. K. Anokhin). In this synthetic activity the leading value gets activity of a cerebral cortex, edges everything is more capable to suppress subcrustal mechanisms I.

However And. it can be shown in a bright form, in particular when activity of bark is weakened and control over underlying subcrustal structures (e.g., in a condition of a dream is broken, at the use of narcotic substances or alcohol).

In a wedge, practice there are numerous examples of how as a result of abnormal increase of activity of the subcrustal centers or decrease in brake influences on them from bark of big hemispheres instinctive activity sharply amplifies. At the same time such phenomena as a giperseksualizm, a gluttony, aggression etc. can be observed.

Cases when a superactivity of the subcrustal structures responsible for implementation are not less frequent And., but having opportunities to be shown in the corresponding behavior, «breaks» in the form of abnormally increased influence on activity of internals, leading to increase in blood pressure, to a spasm of various smooth muscle sphincters went. - kish. path, etc.

Forms of decrease in instinctive activity are described also patol (an aphagia, an adipsia, impotence, etc.).

Specifics And. as objectively reasonable action made it different favourite subject of teleologic and theological reasonings as proof of the wisdom of the creator or different vitalistic and spiritualistic doctrines opposing And. to reason as allegedly more efficient force connected with deep sources of a creative vital rush and therefore as if surpassing reason by definiteness and reliability of the achievements. Some representatives of an irrationalism hypertrophying a role of an instinct in behavior of the person (see. Freydizm ), consider that the reason resides searching; he investigates and is very frequent if not mostly, falls into contradictions and delusions. And. never looks for anything, but always finds. Similar reasonings are disproved by achievements of modern science.

See also Instinctive reflex , Conditioned reflex .

Bibliography: Krushinsky L. V. Formation of behavior of animals is normal also of pathology, M., 1960, bibliogr.; With l it and A. D. Instinkt's m, a riddle of an innate behavior of organisms, L., 1967, bibliogr.; it, Wednesday and behavior, L., 1976, bibliogr.; Haynd R. Behavior of animals, the lane with English, M., 1975, bibliogr.; Sh about in e of N of R. Povedeniye of animals, lane with fr., M., 1972, bibliogr.; Tinbergen N. The study of instinct, Oxford, 1955, bibliogr.

K. V. Sudakov, A. G. Spirkin.