From Big Medical Encyclopedia

INSTINCTIVE REFLEX (specific, inherent reflex) — the constant and inborn reaction of an organism to certain influences of the outside world which is carried out by means of a nervous system and not demanding special conditions for the emergence. The term is entered by I. P. Pavlov during the studying of physiology of higher nervous activity. The B. river arises certainly if the adequate irritation is applied on a certain receptor surface. Contrary to it certainly the category of reflexes was open for the arising reflex by I. P. Pavlov, formation to-rykh requires observance of a number of conditions — conditioned reflex (see).

Physiological feature of B. of river is its relative constancy. The B. river always arises at the external or internal irritations corresponding to it, being shown on the basis of inborn nervous bonds. As the corresponding B.'s constancy of river is result of phylogenetic development of this species of an animal, this reflex received still the additional name «specific reflex».

The biological and physiological role of B. of river consists that thanks to this inborn reaction animals of this look adapt (in the form of reasonable acts of behavior) to constant factors of existence.

Division of reflexes into two categories — on unconditional and conditional — corresponds to two forms of nervous activity of animals and the person, to-rye were accurately differentiated by I. P. Pavlov. B.'s set of river makes the lowest nervous activity while set acquired, or conditional, reflexes — higher nervous activity (see).

Follows from this definition that the river along with implementation of constant adaptive reactions of an animal in relation to action of environmental factors determines by B. by the physiological value also those interactions of nervous processes, to-rye in the sum direct internal life of an organism. I. P. Pavlov attached to this last property of an instinctive reflex especially great value. Thanks to the inborn nervous bonds providing interaction of bodies and processes in an organism, the animal and the person get the exact and steady course of the main vital functions. The principle, on a basis to-rogo will organize these interactions and integration of activity in an organism, self-control of physiological functions is (see).

Classification of instinctive reflexes can be constructed on the basis of specific properties of the acting irritant and biological sense of responses. By such principle classification in I. P. Pavlov's laboratory was constructed. According to it distinguish several types of B. of river:

1. Food, the activator to-rogo is effect of feedstuffs on receptors of language and on the basis of studying to-rogo all fundamental laws of higher nervous activity are formulated. Thanks to spread of activation from receptors of language towards c. the N of page occurs excitement of the branched inborn nervous structures in general making the food center; as a result of such fixed relationship of c. the N of page and work peripheral vehicles form responses of the whole organism in the form of an instinctive food reflex.

2. Defensive, or as it is called sometimes, a protective reflex. This B. the river has a number of the forms depending on what body or what part of an organism is threatened by danger. So, e.g., drawing pain stimulation on an extremity causes otdergivany extremities that protects it from further destructive action.

In a laboratory situation as the irritant causing defensive B. of river usually use electric current from the corresponding devices (the induction coil of Dubois — Raymond, city current with the corresponding undervoltage etc.). If as an irritant apply the movement of air directed to a cornea of an eye, then defensive reflex is shown by a smykaniye a century — a so-called blink reflex. If irritants are strong gases, to-rye pass through upper respiratory tracts, then the delay of respiratory excursions of a thorax will be a protective reflex. The most common in I. P. Pavlov's laboratory is the kind of a protective reflex — an acid protective reflex. It is expressed by strong reaction of an otverganiye (vomiting) in response to injection of solution salt to - you in an oral cavity of an animal.

3. Sexual, to-ry by all means arises in the form of a sexual behavior on an adequate sexual irritant in the form of an individual of an opposite sex.

4. Approximate and research, to-ry it is shown by the bystry movement of the head towards the external irritant which worked at present. The biological sense of this reflex consists in detailed inspection of the worked irritant and in general that external situation, in a cut this irritant arose. Thanks to existence in c. the animal capable is reasonable to answer N of page of inborn ways of this reflex suddenly happened changes in the outside world (see. Approximate and research reaction ).

5. Reflexes from internals, reflexes at irritation of muscles, sinews (see. Visceral reflexes , Tendon jerks ).

The general property of all B. of river is that they can form a basis for education acquired, or conditional, reflexes. One of B. of river, napr, defensive, lead to formation of conditional reactions very quickly, often after one combination of any external irritant to a painful reinforcement. Other B.' ability of river, napr, blink or knee to form temporary bonds with an indifferent external irritant it is expressed to a lesser extent.

It is also necessary to consider that the speed of development of conditioned reflexes is in direct dependence at most of an unconditional irritant.

Specificity of instinctive reflexes consists in exact compliance of response of an organism to character of the irritant operating on receptor devices. So, e.g., at irritation of flavoring receptors of language a certain food reaction of sialadens on quality of the separated secret is in strict accordance with physical. and chemical properties of the eaten food. If food dry, then separates watery saliva if food is rather moistened, but consists of pieces (e.g., bread), the instinctive salivary reflex will be shown according to this quality of food: saliva will contain a large number of a mucous glucoproteid — mucin, to-ry prevents traumatizing food ways.

Thin receptor assessment is connected with a lack of this or that substance of blood, napr, so-called calcic hunger at children in the period of an osteogenesis. Since calcium selectively passes through capillaries of the forming bones, eventually its quantity becomes lower than constant. This factor is a selective irritant of nek-ry specific cells of a hypothalamus, to-ry in turn keeps receptors of language in a condition of a hyperexcitability. So the aspiration at children forms is plaster, whitewashing and other mineral substances, calciferous.

Such reasonable compliance of B. of river to quality and force of the worked irritant depends on extremely differentiated effect of feedstuffs and their combinations on receptors of language. Receiving these combinations of afferent vozbuzhdeniye from the periphery, the central office of B. of river sends to peripheral devices (glands, muscles) efferent excitement, leading to education of a certain composition of saliva or emergence of movements. Really the composition of saliva can be easily changed through correlative change of products of its main ingredients: water, proteins, salts. It follows from this that the central office of salivation can vary quantity and quality of the excited elements depending on quality of the excitement which came from the periphery. Compliance of the unconditional answer of specificity of the put irritation can go very far. I. P. Pavlov developed idea of a so-called digestive warehouse of certain unconditional reactions. E.g., if it is long to feed an animal with a certain grade of food, then digestive juices of its glands (gastric, a pancreas, etc.) eventually get a certain structure on an amount of water, inorganic salts and especially on activity of enzymes. It is necessary to recognize such «digestive warehouse» as reasonable adaptation of congenital reflexes to the established constancy of food reinforcement.

At the same time these examples say that stability, or stability, B. of river is only relative. There is a basis to think that in the first days after the birth specific «mood» of receptors of language is prepared by embryonic development of animals that provides the successful choice of feedstuffs and the systematic course of unconditional reactions. So, if in milk of mother, the Crimea eats the newborn child, to increase percent of content of sodium chloride, then the sucking movements of the child are immediately slowed down, and in nek-ry cases the child actively throws out already accepted mix. This example convinces that inborn properties of food receptors, as well as properties of intra nervous ratios, reflect the most exact image needs of the newborn.

The technique of use of instinctive reflexes

As in practice of works on higher nervous activity of B. of river is the supporting factor and a basis for development acquired, or conditional, reflexes, the question of methodical methods of use of B. of river becomes especially important. In experiments on conditioned reflexes food B.'s use by the river is based on feeding of an animal by these or those feedstuffs from automatically moving feeding trough. At such route of administration of an unconditional irritant direct effect of food on receptors of language of an animal is inevitably preceded by a number of collateral irritations of the receptors relating to various to analyzers (see).

How giving of a feeding trough was innovative, it by all means makes some noise or knock and, therefore, this sound irritant is an inevitable predecessor of the most true unconditional irritant, i.e. irritant of flavoring receptors of language. The technique of direct administration of feedstuffs in an oral cavity, at the same time irrigation of flavoring receptors of language, napr was developed for elimination of these defects, solution of sugar, is the direct unconditional irritant which is not complicated by any collateral agent.

It should be noted, however, that under natural conditions animals and the person never receive food in an oral cavity without preliminary feelings (a look, feeling of a flavor of food etc.). Therefore the technique of direct introduction of food to a mouth has nek-ry abnormal conditions and reaction of an animal to singularity of such procedure.

Except such use of an unconditional irritant, there is a number of techniques, in to-rykh an animal by means of special movements itself receives a forage. The most various devices by means of which the animal (a rat, a dog, a monkey), pressing on the corresponding lever or the button, receives food concern to them — so-called tool reflexes.

Methodical features of a reinforcement an unconditional irritant have undoubted influence on the received experimental results, and, therefore / assessment of results shall be made taking into account B.'s type of river. It especially belongs to comparative assessment of food and defensive B. of river.

While the reinforcement a food unconditional irritant is for an animal a factor of positive biological value (I. P. Pavlov), on the contrary, the reinforcement a painful irritant is an incentive for biologically negative unconditional reaction. From this it follows that «not reinforcement» of well zatverzhenny conditioned reflex an unconditional irritant in that and other case will have the return biological sign. While not reinforcement food of a conditioned excitator leads to negative and often aggressive reaction of an experimental animal, on the contrary, not reinforcement of a prearranged signal electric current conducts to absolutely clear biol, positive reaction. These features of the relation of an animal to not reinforcement of a conditioned reflex can be well revealed by this or that unconditional irritant on such vegetative component what breath is.

Structure and localization of instinctive reflexes

Development of the experimental equipment gave the chance to study physiological structure and food B.'s localization by the river in the central nervous system. Action of an unconditional food irritant on receptors of language is for this purpose studied. The unconditional irritant irrespective of its food properties and a consistence first of all irritates tangoreceptors of language. It is the most bystry type of the excitement which is a part of unconditional irritation. Tangoreceptors produce the most bystry and high-amplitude type of nervous impulsation, to-rye the first extend on a lingual nerve to a myelencephalon and only through nek-ry fractions of a second (0,3 sec.) there nervous impulses from temperature and chemical irritation of receptors of language arrive. Such feature of an unconditional irritant which is shown in consecutive excitement of various receptors of language has huge fiziol, value: in c. N of page conditions for the alarm system by each previous flow of impulsation about the subsequent irritations are created. Thanks to such ratios and features of tactile excitement depending on mechanical qualities of this food in reply only on these excitement salivation can arise earlier, than chemical qualities of food will work.

The special experiments done on dogs and studying of behavior of newborn children showed that such ratios between separate parameters of an unconditional irritant are used in adaptive behavior of the newborn.

So, e.g., in the first days after the birth an irritant of acceptance of food by the child its chemical qualities are decisive. However in several weeks the leading role passes to mechanical characteristics of food.

Information on tactile parameters of food advances in life of adults on the speed of arrival to a brain information on chemical parameters. Thanks to this pattern the feeling of «porridge», «sugar» etc. is born earlier, than the chemical signal will come to a brain. According to I. P. Pavlov's doctrine about cortical representation of B. of river each unconditional irritation along with turning on of subcrustal devices has the representation in bark of big hemispheres. On the basis of the stated above data, and also the oscillographic and elektroentsefalografichesky analysis of distribution of unconditional excitement it was established that it has no uniform point or the center in bark of big hemispheres. Each of fragments of unconditional excitement (tactile, temperature, chemical) is addressed to various points of bark of big hemispheres, and only almost simultaneous initiation of these points of bark of big hemispheres establishes between them system connection. These new data meet I. P. Pavlov's expectations of structure of a nerve center, however demand change of the existing ideas of «cortical point» of an unconditional irritant.

Researches of cortical processes by means of electric devices showed that the unconditional irritant comes to a cerebral cortex in the form of very generalized flow of the ascending vozbuzhdeniye, and, obviously, to each cell of bark. It means that any excitement of sense bodys preceding an unconditional irritant cannot «escape» its convergence with unconditional excitement. These properties of an unconditional irritant strengthen idea of «convergent short circuit» of a conditioned reflex.

Cortical representations of unconditional reactions are such cellular complexes, to-rye take active part in formation of a conditioned reflex, i.e. in switching functions of bark of big hemispheres. In character the cortical representation of B. of river shall have afferent character. It is known that I. P. Pavlov considered bark of big hemispheres «the isolated afferent department of the central nervous system».

Compound instinctive reflexes. I. P. Pavlov marked out special category B. of river, in to-ruyu included inborn activity, having cyclic and behavioural character — emotions, instincts and other manifestations of difficult acts of inborn activity of an animal and the person.

In initial opinion of I. P. Pavlov, difficult B. rubles are function of «the next subcortex». This general expression is meant as a thalamus, a hypothalamus and other parts interstitial and a mesencephalon. However further with development of ideas of cortical representations by B. of river this point of view was postponed also for difficult B.' concept of river Thus, difficult B. by river, napr, the emotional category, incorporates a specific subcrustal part, but at the same time course of this difficult B. of river at each separate stage has representation in a cerebral cortex. This point of view of I. P. Pavlov was confirmed with researches of the last years using a method of a nevronografiya. It was shown that a number of cortical areas, napr, orbital bark, limbic area, has a direct bearing on emotional manifestations of animals and the person.

According to I. P. Pavlov, difficult B. of the river (emotion) represent «the blind force» or «the main source of force» for cortical cells. The regulations on difficult B. of river and on their role stated by I. P. Pavlov at that time were in formation of conditioned reflexes only at a stage of the most general development, and only in connection with opening fiziol, features of a hypothalamus, reticular formation of a brainstem deeper studying of this problem became possible.

From the point of view of I. P. Pavlov, the instinctive activity of animals including several various stages of behavior of an animal is also difficult B. of river. Features of this type of B. of river consist that separate stages of performance of any instinctive action are connected with each other by the principle of a chain reflex; however further it was shown that each such stage of behavior shall have by all means the return afferentation) from results of the action, i.e. to make process of comparison of really received result to earlier predicted. Only after that the following stage of behavior can form.

In the course of the painful B.'s research of river it was revealed that painful excitement undergoes considerable transformations at the level of a brainstem and a hypothalamus. From these structures unconditional excitement is generalized covers all areas of bark of big hemispheres at the same time. Thus, along with mobilization in bark of big hemispheres of the system bonds inherent to this unconditional excitement and the rubles making a basis of cortical representation of B., the unconditional irritation makes also generalized action on all bark of big hemispheres. In the elektroentsefalografichesky analysis of cortical activity this generalized action of an unconditional irritant on bark of big hemispheres is shown in the form of desynchronization of cortical wave electric activity. Carrying out painful unconditional excitement to a cerebral cortex can be blocked at the level of a brainstem by means of special substance — aminazine. After administration of this substance in blood even the strong damaging (nociceptive) unconditional excitement (a burn hot water) does not reach a cerebral cortex and does not change it to electric activity.

Development of instinctive reflexes in the embryonal period

Inborn character of B. of river especially clearly comes to light in researches of embryonic development of animals and the person. On different terms of an embryogenesis it is possible to track each stage of structural and functional formation of B. of river. The vital functional systems of the newborn are completely consolidated by the time of the birth. Separate links sometimes of difficult B. of river as, e.g., a sucking reflex, various parts of an organism include, it is frequent on a considerable distance from each other. Nevertheless they selectively combine various bonds and gradually make functional whole. Studying of maturing of B. of river in an embryogenesis gives the chance to understand constant and rather unchangeable adaptive effect of B. of river during the drawing the corresponding irritant. This property B. of river is connected with formation of the mezhneyronalny relations on the basis of morphogenetic and genetic patterns.

B.'s maturing by the river in the embryonal period is not identical to all animals. As maturing of functional systems of an embryo makes the major biological sense in preservation of life of newborn this species of animals, depending on features of living conditions of each species of animals the nature of structural maturing and final registration of B. of river will precisely correspond to features of this look.

So, e.g., structural registration of spinal reflexes of koordination is various at birds, to-rye later hatching of egg at once become completely independent (chicken), and at birds, to-rye later hatching of egg are long time helpless and are on care of parents (rook). While the chicken stands on the feet at once after hatching and every other day uses them absolutely freely, at a rook, on the contrary, before everything front extremities, i.e. wings enter activity.

Even more clearly this selective growth of nervous structures of B. of river takes place in fetation of the person. Very first and clearly the coming to light motor reaction of a human fruit is the grasp reflex; he is found on the 4th month of an antenatal life and is called by the annex of any firm subject to a palm of a fruit. The morphological analysis of all links of this reflex convinces that before it comes to light, a number of nervous structures is differentiated in mature neurons and combines among themselves. Myelination of the nervous stipitates relating to sgibatel of fingers begins and comes to an end earlier, than this process is developed in nervous trunks of other muscles.

Phylogenetic development of instinctive reflexes

According to the known position of I. P. Pavlov, rubles are B. a consequence of fixing with natural selection and heredity of those reactions acquired throughout the millennia, to-rye correspond to the repeating environmental factors and are useful to this look.

There are bases to claim that the most bystry and successful devices of an organism can depend on favorable mutations, to-rye are selected afterwards by natural selection and already descended.

See also Higher nervous activity , Instinct , Reflex , Conditioned reflex .

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P. K. Anokhin.