ANALYZERS

From Big Medical Encyclopedia

ANALYZERS — the formations of the central and peripheral nervous system which are carrying out perception and the analysis of information about yavlendyakh, occurring both in the Wednesday surrounding an organism, and in the organism. The term is entered into physiological science by I. P. Pavlov. The doctrine about And. succeeded the idealism and agnosticism dominating in sensory physiology. Originally the sensory physiology developed as a branch of appropriate sections of physics (optics and acoustics) and thanks to R. Descartes's efforts, G. Helmholtz, etc. saved up many facts characterizing physical properties of organs of sight and hearing.

Pavlov's doctrine about And. laid the foundation of natural-science materialistic understanding of the nature and mechanisms of feelings, processes of training and behavior. According to Pavlov's classification all And. are divided into two groups: external and internal. And., the carrying-out analysis and synthesis of the phenomena of the environment, are called external, or exteroceptive (see. Exteroception ). Treat them visual, acoustical, olfactory, tactile, etc. And., carrying out the analysis of the phenomena occurring in an organism are called internal, or interoceptive (see. Interoception ). They give information on a state went. - kish. path, cardiovascular system, easy and other internals. One of the main internal analyzers is motor analyzer (see). It informs a brain on a condition of the muscular and joint device. His receptors (see. Proprioceptors ) have complex structure and are placed in muscles, sinews and joints. The fact that the muscular system is not only the executive motor office, but also a peculiar sense body was known at the beginning of 19 century. With full definiteness Bell (S. of Bell, 1826) in the book «Neuromotor Ring» wrote about it. Afterwards I. M. Sechenov (1863) showed that «the dark muscle sense» possesses an important role in mechanisms of regulation of movements. An intermediate position between external and internal And. borrows vestibular And. It is in an organism (inner ear), but is excited by external factors (acceleration and delay of the rotary and rectilinear motions).

Everyone And. consists of peripheral (receptor) department, a conduction part and cortical department. Peripheral department And. represents specialized nerve terminations — receptors (see), reformative certain types of energy (light, sound, thermal) in process of nervous excitement. Thanks to specialization of receptors the first analysis of external irritants — decomposition whole on parts, distinguishing of character and quality of signals is carried out. At the same time all types of external energy (light, a sound, heat and cold, chemical and mechanical influences, etc.), being transformed to nervous process, come to a brain in the form of homogeneous signals. However, despite it, the brain precisely differentiates information value of these signals. Experimental data of Adrian (E. D. Adrian, 1931), Granite (R. Granit, 1957), Rashton (W. A. H. Rushton, 1961), Barlow (N. V. of Barlow, 1961), Hartlayn (H. Hartline, 1961), etc. is allowed to imprison that it is caused by that the signals arising in receptor part A., are exposed to coding. Essential value in mechanisms of coding of information is gained by the frequency and number of the impulses extending on esodic nerves. As the nerve transfers in each small interval of time, does not transfer impulses, it is assumed that information transfer is carried out by a binary code (an impulse — a pause). Bullock (T. H. Bullock, 1969) considers that, in addition to pulse code communication, information transfer between neurons is carried out also on not pulse type, i.e. thanks to specific electrotonic bonds. However in system A. the pulse code type of information transfer is the basic.

In mechanisms of decoding of information essential value is gained by features of the organization and functioning of conduction parts A. and their cortical projections. Conduction part A. structures of limbic system [V. Nauta, 1963] and a cerebellum is presented not only by various kernels of a thalamus and their projections to the respective areas of a cerebral cortex, but also such educations as a reticular formation [Moruzzi, Megun (G. Moruzzi, H. W. Magoun), 1949], [R. S. Snider, 1950]. Existence of these bonds and functional features of a reticular formation and cerebellum allow to carry them to structural elements external and internal And.

Thin electrophysiologic researches [V. Amassian, 1950; Mauntkasl (V. Century of Mountcastle), 1964; R. A. Durinyan, 1965, etc.] it is established that the principle of the extensive (extending) projection of afferent systems in process of their ascension to the highest structures of a brain is general for all levels of c. N of page. Most brightly it is expressed in talamo-cortical projections. It is established that the afferent signal which came even on one fiber is transferred to a set of neurons in specific, associative and nonspecific kernels of a thalamus, and they in turn switch each impulse to a bigger amount of cortical neurons. In a cerebral cortex where there is the highest analysis and synthesis of the arrived information, each analyzer has a certain localization. So, visual And. it is located preferential in occipital area, motive — in parietal, acoustical — in temporal area of bark of big hemispheres etc. Adrian's works, Woolsey (Page N. Woolsey, 1943), etc. allowed to establish Penfild (W. Penfield, 1954) that some And. have several projective areas located in various parts of a cerebral cortex and that it is possible to speak about dual representation in a cerebral cortex of at least somatic, acoustical, visual and visceral

A. V cortical departments And. there are neurons reacting only to one touch irritation. These are, as a rule, specific projective neurons. Near them there are pespetsifichesky nervous cells reacting to various touch irritants, i.e. possessing multitouch convergence (see. Cerebral cortex ). Especially there is a lot of such neurons in associative area of a cerebral cortex. Thanks to convergence of vozbuzhdeniye on cortical neuron interaction between many is possible And. On the basis of the analysis of the signals coming to a brain from external and internal receptors afferent synthesis (see) adequate information with the subsequent formation of the program of behavior, the device of assessment of results of action is carried out (see. Acceptor of results of action ).

By researches of the last years it is shown that activity And. it is not exhausted only by the analysis of the external and internal information, and includes also the return influence of the highest departments on receptor and conduction parts A. Sensitivity of receptors (the perceiving part A.), and also functional condition of transfer relays (conduction part A.) are defined by the descending influences of a cerebral cortex that allows an organism from many irritants actively to select touch information most adequate at present. It is expressed by a vsmatrivaniye, a listening of an animal etc. that physiologically is explained in the first case by reduction of the threshold to visual irritants, and in the second — to acoustical irritants. For studying And. the method of conditioned reflexes, electrophysiologic and morphological methods are applied.


Bibliography: Bullock T. X. Language of nervous cells, in book: System organization fiziol. functions, under the editorship of V. V. Parin, page 11, M., 1969; Granite P. An electrophysiologic research of reception, the lane with English, M., 1957, bibliogr.; Guselnikov V. I. An electrophysiologic research of analizatorny systems in phylogenesis of vertebrata, M., 1965, bibliogr.; Durinyan R. A. Central structure of afferent systems, L., 1965, bibliogr.; Mauntkasl V. Some functional properties of somatic afferent system, in book: The theory of communication in touch systems, the lane with English, under the editorship of G. D. Smirnov, page 185, M., 1964, bibliogr.; Mogendovich M. R. and Temkin I. B. Analyzers and internals, M., 1971, bibliogr.; Pavlov I. P. Complete collection of works, t. 3, book 1 — 2, M. — L., 1951.

L. S. Gambaryan.

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