From Big Medical Encyclopedia

HIGHER NERVOUS ACTIVITY — the integrative activity of the highest parts of the nervous system providing individual behavioural adaptation of the person or the highest animals to the changing conditions of surrounding and internal environment. Having entered the term B. of N of as a physiological equivalent of the concept «mental activity», I. P. Pavlov emphasized its difference from «the lowest nervous activity».

The concept of the lowest nervous activity combines set instinctive reflexes (see) this organism. These reactions are rather constant, arise on adequate, biologically significant irritation of the respective receptive field. Instinctive reflexes are hereditarily the predetermined reactions inherent under certain conditions to all representatives of this species. Instinctive reflexes provide the coordinate activity of an organism directed to maintenance of constancy of internal environment (see. Homeostasis ), napr, the level of blood, osmotic and oncotic pressure, a sugar content in blood, a ratio of concentration of carbon dioxide and oxygen, etc. Mechanisms B. of N of turn on when the lowest nervous activity cannot timely provide optimum adaptive reaction because of inconstancy, variability of the environment.

With the advent of V. and. live organisms gained ability to react not only to direct action of biologically significant agents (food, sexual, painful etc.), but also on their remote signs, allocating formal communication between biologically important event and conditions which are naturally preceding it. The irritants characterizing these conditions become conditioned excitators, i.e. the signals including the developed adaptive behavior.

Thus, V. of N of forms on the basis of the lowest nervous activity and represents a complex of the reactions of different biological quality acquired by an organism which are developed fixed or disappearing under certain conditions in response to irritation of any receptive zones (see. Conditioned reflex ).

At the heart of ideas of V. and. and the lowest nervous activity the materialistic ideas about reflex mechanisms of mental processes lie (see. Reflex theory ), for the first time formulated and developed in 1863 by I. M. Sechenov in the book «Reflexes of a Brain».

The doctrine about V. and. — the section of physiology based by I. P. Pavlov studying neurophysiological mechanisms of individual adaptive activity and pattern of their influence on all functions of a complete organism.

By means of developed by it for objective studying of V. of N of of a method of conditioned reflexes I. P. Pavlov opened fundamental laws of V. of N of. To them it is established that formation of a conditioned reflex requires emergence in c. and. page, first of all in its highest departments, temporary communication (association, short circuits) between the neurons perceiving conditional irritation and the neurons entering an arch of an instinctive reflex. Thanks to associations of varying complexity the irritants indifferent earlier preceding this or that activity of an organism become a signal of this activity, gain ability to create in c. N of page the advancing arousing the corresponding biological quality. E.g., the irritant which was repeatedly preceding the act of food and became to conditional raises a tone of the food center, strengthens food motivation, stimulates secretion of digestive glands, starts pishchedobyvatelny reaction. Conditional reactions, to-rykh the advancing food excitement is the cornerstone, are carried out to the act of food, precede it, provide its full value.

According to the law of the power relations of I. P. Pavlov conditional reactions especially are expressed, than intensity of a conditioned excitator is higher.

The advancing excitement of a defensive modality (see. Afferent synthesis ), developing owing to conditional defensive irritation, allows an organism to prevent imminent danger avoiding or active protection. It is obvious that the advancing excitement caused by a conditioned excitator provides not only biologically reasonable adaptation to the environment, but also is the cornerstone of active influence on Wednesday. The mechanisms of the advancing excitement which are carried out at the highest animals and the person on the basis of the activating influences of subcrustal educations on a cerebral cortex ascending biologically specific, are studied in many neurophysiological and neurochemical laboratories of the world.

By microelectrode researches it is proved that from 30 to 94% of neurons of cortical and subcrustal educations are capable to participate in short circuit of temporary bonds. After several combinations of a conditioned excitator and an unconditional reinforcement they gain ability to answer a conditioned excitator with a new form of reaction.

Stable reactions of neurons to a conditioned excitator arise much earlier, than the corresponding reflex is shown behavioural. Despite intensive researches, the specific mechanism of short circuit of temporary bonds remains not clear. The existing theories of this process need additional experimental check. Treat them: P. K. Anokhin's theory about convergent short circuit focusing attention on specific chemical reorganizations in cytoplasm of postsynaptic neuron and A. I. Roytbak's concept about miyelinoobrazuyushchy function of oligodendrocytes at the level of presynaptic bombways.

Complex systems of temporary bonds at the highest animals and the person allow to develop conditioned reflexes not only. on the basis of unconditional (conditioned reflexes of the first order), but also on the basis of earlier created and strengthened conditioned reflexes, i.e. conditioned reflexes of the second, third and higher orders.

One of the most difficult phenomena of V. of N of is dynamic stereotype (see). According to I. P. Pavlov's doctrine the dynamic stereotype represents the sequence of processes of excitement reflecting in the same way repeating influences of the environment. As the uniform functional complex a dynamic stereotype forms thanks to emergence of communication between trace excitement from action of the previous signal and the subsequent excitement from a new conditioned excitator. The main quality of a dynamic stereotype is its autonomy: in the developed stereotype reaction is carried out not so much on a conditioned excitator how many on its place in system of influences and reactions. Adaptive value of a dynamic stereotype is big. With its help automatic, and economical adaptation to consistently repeating influences of the environment is carried out optimum, in this case. All our habits, a daily routine, system of behavior — serve as display of a dynamic stereotypy. In new system of irritants the stereotype of reaction changes therefore it also is called dynamic. Development of a dynamic stereotype happens not at once, but in process of repetition of system of irritants and reactions it becomes rather steady. Alteration of a dynamic stereotype is heavy loading for a nervous system and can cause V.'s disturbances N of.

Idiosyncrasy of temporary bonds consists that they keep the value only until correspond to real conditions of reality. At disturbance of this compliance conditioned-reflex reaction dies away and the conditioned excitator loses the alarm value. According to I. P. Pavlov, the ugasheniye of conditional reactions is carried out by means of processes braking (see). Depending on conditions of emergence distinguish unconditional — inborn braking and conditional — developed in individual life of an organism. Refer external and ultraboundary inhibition to unconditional braking. The source of external inhibition lies out of the centers of a conditioned reflex. External inhibition arises at action of foreign irritants, i.e. the new unusual situation, painful irritants or some other factors causing strong contagious excitation. The most important feature of external inhibition is its fading at repeated influences. Ultraboundary braking — decrease in uslovnoreflektorny activity as a result of influence of superstrong or superlong irritants. Ultraboundary braking, promoting recovery of the exhausted nervous cells, plays a role of a protective factor and therefore is considered as guarding.

Conditioned inhibition initially arises in nerve centers of a conditioned reflex at a nepodkreple-niya of a conditioned excitator. Distinguish the following types of conditioned inhibition: ugasatelny, late, differentsirovochny and a conditional brake (see. Braking ). Conditioned inhibition makes an integral part of any form of the acquired activity of an organism, providing the thinnest forms of adaptation to the environment.

Century of N of represents analitiko-synthetic activity of bark and the next subcrustal formations of a brain, edges is shown in ability to allocate its separate elements from the environment and to combine them in the combinations precisely corresponding to the biological importance of the phenomena of the world around. The act of formation of temporary communication between two irritations is complex synthetic process. Processes of the highest synthesis are carried out by all cerebral cortex while the analysis of an irritant is preferential made by certain projective zones — the double representations of the respective receptor fields which received the name of the cortical ends analyzers (see). Analyzers can be subdivided into the external, analyzing influences of external environment (olfactory, visual, acoustical, tactile), and internal, e.g. statokinetic. Analitiko-sintetichesky activity of the highest departments of c. and. the page is carried out at the obligatory ascending, biologically specific activating influence on bark from subcrustal educations (see. Subcrustal functions ). According to P. K. Anokhin's school, the ascending activation of bark of big cerebral hemispheres has different neurochemical specifics depending on biological quality of the happening activity, from its emotional basis. Selective neurochemical activation reconstruct chemism of cortical neurons, do them more susceptible to an afferent impulsation. As a result neurons begin to react to earlier subthreshold afferent influences. Due to this process ability of neurons to selection of information increases that promotes the thin analysis of influences of the world around and internal environment of an organism.

The attempt of rapprochement of other directions in a research of behavior is observed: behaviorism (see) and ethology (see) with the doctrine about V. and. The classical behaviorism put the task objective studying of external manifestations of behavior, rejecting subjective (interospektivny) approach and attempts of the neurophysiological analysis. However the modern behaviorism approaches direct studying of processing of signals of the outside world in c. N of page and neyronalny mechanisms of formation of behavior. Along with a classical method of conditioned reflexes the tool conditioned reflex which was earlier applied by behaviourists became a widespread method of a research B. and. The tool conditioned reflex (an operant behavior, a conditioned reflex «the movement — a reinforcement») is for the first time described under the name of a conditioned reflex of the second type S. Miller and E. Konorsky in 1933 Etologi, having concentrated attention on an innate instinctive behavior, opened many new adaptive mechanisms, napr, an instant zapechatlevaniye (imprinting). The facts which are saved up by etologa allowed to expand ideas of the lowest nervous activity — V.'s basis of N of. The doctrine about V. of N, a behaviorism and ethology, thus, supplement each other in a research of complete behavior.

I. P. Pavlov's doctrine about V. and. also successful development in researches of his pupils and followers gained wide recognition in domestic and world neurophysiology and experimental psychology (L. A. Orbeli, K. M. Bykov, P. K. Anokhin, P. S. Kupalov, E. A. Asratyan, etc.). The systems approach developed by P. K. Anokhin's school to the analysis of mechanisms B. of N of is especially perspective. From these positions B. and. is considered as functional system and represents dynamically forming organization selectively combining diverse central and peripheral offices for obtaining useful adaptive result (see. Functional systems ). The net adaptive result is a backbone factor. It, but not conditional as was considered earlier, an irritant directs behavioural reaction and defines the nature of the functional system necessary for achievement of adaptive effect. Within the theory of functional system an initial stage of formation of any behavioural act is afferent synthesis (see), in time to-rogo there is a simultaneous processing of motivational excitement, obstanovochny afferentation, the results of last experience and vozbuzhdeniye caused by a conditioned excitator taken from memory. On the basis of afferent synthesis the optimum way of achievement of useful result on the basis of full information exchange of a number of diverse vozbuzhdeniye is defined. The importance in afferent synthesis belongs to motivational excitement, subjective expression of the objective requirement of an organism dominating at present (see. Motivations ). With the help approximately - research reaction and afferent synthesis active selection of information necessary for formation of «the purpose of action» and decision-making, «is carried out as how to do» for satisfaction of initial motivation. The Obstanovochny afferentation expresses all set of the external factors accompanying adaptive activity. Under the influence of motivational excitement the obstanovochny afferentation creates in c. N of page the branched afferent interaction preparing a form of reaction, specific to this situation. A specific place in processes of afferent synthesis is held by mechanisms of extraction from memory of results of the accumulated experience connected with satisfaction this motivation in the past. They allow to mobilize the most adequate for achievement of useful effect fragments and results of last experience.

The large role in processes of afferent synthesis is played also by such dynamic processes as the general activation of cortical activity facilitating all types of necessary interactions. These neurodynamic processes provide continuous search and assessment of possible results of activity throughout all afferent synthesis before the final decision to obtaining the result which is fullestly satisfying motivation in this specific situation is made.

As a result of interaction of motivational initiation of obstanovochny influences and memory the hidden prestarting integration of vozbuzhdeniye — neurophysiological substrate of «purpose», «intention to action» is created. There is a decision-making to action and programming of mechanics of this action, a cut under the influence of a starting incentive, i.e. a conditioned excitator, is implemented in the form of purposeful behavior.

Precedence of formation of «purpose» to its implementation is especially brightly shown in V. and. of the person, in his social behavior, in plans for the future when the purpose becomes an important driving incentive, and its implementation can be removed on very long terms.

The neurophysiological device programming the purpose to action and on the basis of the constant return afferentation coming to c. the N of page from real results of perfect action who is actively controlling the course of its performance was called P. K. Anokhin acceptor of results of action (see). Being the universal mechanism for all types of behavior, the acceptor of result of action is implemented on various nervous substrates. Performing function of checking of results with the set «purpose», the acceptor of result of action is the device of programming of future events reflecting general function of a brain.

If the return afferentation about results of action corresponds to earlier programmed parameters of an acceptor of result of action, it becomes authorizing, i.e. fixes this form of the behavioural act. When the result of action does not correspond to the intention which developed on the basis of afferent synthesis, arises approximate and research reaction (see), followed by searches of new forms of adaptation. Idiosyncrasy of approximate and research reaction consists in broad mobilization of analizatorny systems of an organism due to excitement of the reticular formation of a brainstem having the activating effect on bark of big hemispheres. Tonic action of a subcortex on cortical analizatorny structures provides optimum conditions of cortical excitability for association (association) of external irritations and elaboration of new conditional reactions. Relationship of oriyentirovochnoissledovatelsky reaction with various, already created on the basis of temporary bonds activity of an organism is shown in three types. Most often the conflict relationship consisting that oriyentirovochnoissledovatelsky reaction brakes all other types of activity meets. It is proved in classical experiments of I. P. Pavlov on external inhibition. In other cases the excitement arising during approximate and research reaction can be summed up with the current activity and strengthen it under the law dominants (see). So, e.g., at food excitement any new indifferent irritant causes a feeding response. And, at last, the third form of relationship when approximate and research reaction reveals not the current activity, but some hidden dominant, usually defensive character arising under certain circumstances in this situation, but which is not shown in usual conditions.

An essential role in formation of behavioural acts is played by biological quality of unconditional reaction, namely: its value for preservation of life. In the course of evolution this value was fixed in two opposite emotional states: positive and negative, to-rye at the person make a basis of his subjective experiences — pleasures and displeasure, pleasures and grieves. In all cases the purposeful behavior is under construction according to the emotional state which arose at action of an irritant. During behavioural reactions of negative character tension of vegetative components, especially cardiovascular system, in some cases, especially in continuous so-called conflict situations, can reach big force that causes disturbance of their regulatory mechanisms (vegetative neurosises).

In the course of historical development of fauna morphological substrate of higher nervous activity, the functional organization and mechanisms of analitiko-synthetic activity were improved. If in behavior of invertebrates and the lowest vertebrate animals inborn forms of nervous activity prevail, then the highest animals have dominating acquired forms of nervous activity which reached the greatest perfection at the person. At this level of phylogenetic development there were qualitatively new features of V. of N of connected with emergence of the speech. Specific quality of the word as signal is its semantic contents reflecting the generalized image of specific objects and the phenomena of surrounding reality in the abstracted look. That is why, according to I. P. Pavlov, the word is «a signal of signals». The word became the means of communication between people, a specific form of the interhuman relations. To century of N of of the person it is presented by two alarm systems. The first alarm system is connected with direct perception of the outside world by means of sense bodys. It is inherent in both animals, and the person. The second alarm system is caused by development of the speech; this system of verbal signals of reflection of reality is inherent only to the person.

At the person the second alarm system develops gradually, and in the first years of life the fixed assets of nervous activity are made by conditional reactions of the first alarm system. With emergence of the second alarm system qualitatively new property V.n.d appears. — ability to abstraction and generalization of uncountable signals of the previous system. I. P. Pavlov wrote that «if our feelings and representations relating to the world surrounding us are for us the first signals of reality, specific signals, then the speech, specially first of all the kinaesthetic irritations going to bark from speech bodies are the second signals, signals of signals. They represent derivation from reality and allow generalization, as makes our personal, special and human highest thinking creating at first universal empiricism, and at last and science — the tool of the highest orientation of the person in the world around and itself».

The neurophysiological structure of the speech, as well as any functional system, includes a stage of afferent synthesis, on a basis the cut develops the decision to tell some phrase or to state judgment. Together with it also the acceptor of result of action with all afferent parameters of future speech forms. Step-by-step control in the form of the return afferentation of the pronounced words excludes a possibility of a mistake in expression of the whole thought created in a stage of «decision» (see. Speech ).

Animals and the person have specific features of V. of N of, to-rye are shown in various speed of education and consolidation of conditional reactions, in unequal speed of development of conditioned inhibition, alteration of conditional reactions on new alarm value of conditioned excitators, etc. These distinctions are defined by typological features of V. of N of. The main inborn properties of processes of excitement and braking are the basis for classification of types of Accusative of by I. P. Pavlov: force, steadiness. On the basis of these parameters distinguish four types: the sanguine person, the choleric person, the phlegmatic person and the melancholiac (see. Types of higher nervous activity ).

Though representatives of various typological features of V. of N of have characteristic features of behavior, nevertheless I. P. Pavlov specified that the image of behavior of the person is caused not only inherent properties of a nervous system (genotype), but also those influences which fell and constantly fall on an organism during its individual existence, i.e. depend on continuous education and training in the most extended sense of these words. V. which is finally developing on this basis and. of an animal and the person is alloy from the lines of type and changes caused by external environment (a phenotype, character). Forms of behavior of animals and especially the person, his character considerably depend on living conditions and education.

At the person Pavlov distinguished the following private types determined by a ratio of the first and second alarm systems: 1) cogitative — with emphasized dominance of the second alarm system; 2) are art y — with bright manifestations of the first alarm system and 3) averages y the type, belongs to Krom the vast majority of people: both alarm systems in a due measure are counterbalanced. Private types B. of N of of the person are finally not studied. In clinic the doctrine about V. and. can be used in two aspects: use of ideas of types B. of N of in the choice of specific medical tactics of treatment of each this patient and specific impact on V. of N of in psychiatric practice (uslovnoreflektorny therapy of harmful bents and habits, napr, treatment of alcoholism Teturamum, treatment of heavy smokers lobeline, therapy of sexual perversions and mn. other). S. P. Galperin and A. E. Tatarsky (1973) in detail described modern methods of a research B. of N of of the person in an experiment and clinic.

Problems B. of N of are widely developed around the world. In our country the main centers for a research B. and. are Ying t of higher nervous activity of Academy of Sciences of the USSR, Ying t of physiology of Pavlov of Academy of Sciences of the USSR (Leningrad), Ying t of normal physiology of the USSR Academy of Medical Sciences, Ying t of psychology of Academy of Sciences of the USSR. Researches are conducted also at departments of physiology of medical institutes and on biological f-t ah of high fur boots. In the USSR «The magazine of higher nervous activity» is issued, conferences and meetings are regularly held.

Abroad researches in the area B. of N of are conducted within the research of questions of physiology, psychology and psychophysiology.

The doctrine about V. and. has huge theoretical and practical value. It expands natural-science base of dialectic materialism and the Lenin theory of reflection, serves as weapon in ideological fight against manifestations of idealism. Being one of the greatest achievements of natural sciences, it created the new chapter of physiology having huge value for medicine, psychology, pedagogics, cybernetics, the scientific organization of work and many other fields of scientific practical activities of the person.

Bibliography: Anokhin P. K. Biology and neurophysiology of a conditioned reflex, M., 1968, bibliogr.; Voronin L. G. A course of lectures on physiology of higher nervous activity, M., 1965, bibliogr.; Galperin S. I. and Tatar A. AA. Techniques of a research of higher nervous activity of the person and animals, M., 1973, bibliogr.; To about N about r with to and E. Integrative activity of a brain, the lane with English, M., 1970; L and about r and. Metabolic and pharmacological fundamentals of neurophysiology, the lane with fr., M., 1974, bibliogr.; Miller D., and-lanter E. and At bra To. Plans and structure of behavior, the lane with English, M., 1964; Pavlov I. P. Complete works, t. 1 — 6, M., 1951 — 1954; Penfild U. and Roberts L. The speech and brain mechanisms, the lane with English, M., 1964, bibliogr.; P about N at and e in and A. G. Imprinting, L., 1973, bibliogr.; P about y TB and to A. I. New hypothesis of the mechanism of formation of temporary bonds, Neurophysiology, t. 1, No. 2, page 130, 1969, bibliogr.; Selivanova A. T. and about l and to about in S. N. Cholinergic mechanisms of higher nervous activity, L., 1975; Sechenov I. M. Reflexes of a brain, M., 1961; System анг^лиз integrative activity of neuron, under the editorship of P. K. Anokhin, M., 1974; At about t with about D. B's N. Psychology as science about behavior, the lane with English, M. — L., 1926; Physiology of higher nervous activity, under the editorship of B. N. Chernigovsky, p.1 — 2, M., 1970; Experimental psychology, under the editorship of P. Fress and Ge. Piaget, lane with fr., century 1 — 4, M., 1966 — 1973.

P. K. Anokhin, A. I. Shumilina, V. N. Uranov.