84. Переработка и контроль сенсорной информации высшими отделами нервной системы в условиях поведения. В. Крогер (84. Sensory Information Processing and Control in Higher Nervous System Functioning and Behavior. William S. Kroger)

Institute for Comprehensive Medicine, Beverly Hills, California, USA

The manner in which the central nervous system utilizes sensory processing and control of information can be studied in three ways. First, by attempting to observe physiological events such as electrical and chemical reactions or other information conveying mechanisms and energy conversions that are involved in nervous system dynamics. Second, behavior can be studied as it occurs spontaneously or during experimentally designed situations. Third, one can attempt to develop physical models which retain certain essential characteristics of sensory processing of information and control. These three approaches may be labeled microscopic (the examination of detailed events in the CNS), macroscopic (the examination of behavior), and correlation with mathematical-physical models of ANS control processes.

Since the first two have been extensively described to understand information processing, the emphasis of this presentation will be on the third approach - the physical model. This model is not to be confused with mathematical analogues of neuro-behavioral functioning. Rather, it compares the evolutionary neurophysiologic development of the complex controls built into human system design for self-regulation of homeostatic or adaptive mechanisms with those utilized by systems engineers for electronic high-speed "thinking machines".

With these goals in mind, the author brings together recent cross-disciplinary exchange of information from the fields of cybernetics, general semantics, anthropology, neurophysiology and clinical experience to offer a general theory of sensory processing and control. The author has chosen hypnosis as his model, as this age-old process is the best way to qualitatively remove the uncertainty in human-to-human communication. Engineers are well aware that whenever a system adjusts its feedback networks to increase the signal to noise ratio, it is functioning optimally. For example, to achieve homeostasis or dynamic equilibrium negative feedback is required. In hypnosis this "steady state" has been called everything from Nirvana, exaltation, to Union with God. The transactional process referred to as hypnosis allows better receptivity and greater objectivity of the meaningfulness of words because of cortical "selective attention and selective inattention" brought about by the associated relaxation and concentration.

The author also suggests that hypnosis, an autonomic, adaptive control response built into the design of higher living systems, at one time may have been necessary in humans as a self-protecting mechanism. This was especially true where either the cortex or the various senses had not achieved their maximum development. The hypnotic response thus may be an atavism - a reversion analogous to the inanimate state of catalepsy so commonly observed in frightened animals when they "freeze to the landscape" in order to escape detection.

However, even though hypnotic suggestibility is an archaic mental function, the regression is not at the behavioral level, but rather at the perceptual or mental functioning level. The author does not suggest that primitive man lived in a constant state of hypnosis; rather, that in the phylogenetic development of the nervous system, higher functions of the secondary signaling system of higher CNS elaboration (analogical) retained their ability to control the more primitive mechanisms. This autonomic control process results, in part, by trial and error learning consisting of adaptive or maladaptive behavior. These autonomic functions are built into the various accumulating lower brain centers for selectively correlating and data processing of information on the basis of experiential inputs. This frees the cortex for the more specialized complex problems of adaptation and survival. The modern brain's fast readout and superior analyzer-integrator systems suggest clues for understanding its cognitive, evaluative and integrative and developing concepts capable of discovering the mechanisms of its own functioning.

The reticular activating system (RAS) also is an ancient brain structure whose function was probably that of maintaining greater arousal. In the modern brain, the ascending reticular activating system (ARAS) with its two-way feedback, reverberating circuits to such higher and lower brain centers, selectively filters incoming sensory stimuli, not only for maintaining selective arousal but for integrating incoming sensory information within awareness. The ARAS governs discriminatory functioning (filtering of incoming stimuli) during hypnosis. The monotonic stimuli in hypnosis tend to focus awareness to important inputs in line with the law of dominant effect: a strong stimulus and well-conditioned reflex displace a weaker one. This parallels the situation when the organism is threatened by imminent danger. For instance, a sleeping person generally awakens in response to a strange sound; that is, a condition of selective attention exists.

Pavlov was the first to note that in neuroses and psychoses a state of excitation occurs in which the cortical neurons become, as it were, weaker and less efficient. Hypnosis or internal inhibition has a protective feature similar to the nonspecific therapeutic effects of sleep and tranquilizers in emotionally disturbed individuals. Recent Russian experiments show that oscilloscopic representations of the brain's electrical potentials make a bioelectric mosaic of different cortical areas. In well-adjusted persons, the resultant mosaics show continual and rapid changes in potential distributed at random over the cortex. This is greatly reduced in severely disturbed individuals. Tranquilizers, sleep, and hypnosis increase the activity of the bioelectric mosaic.

These observations on the evolutionary development of brain function parallel the activity patterns of servomechanisms (automatically controlled machines) in which there is a signal input environment flowing into a purposeful or goal-directed machine. Although reasoning by analogy often can be faulty, the author is well aware that despite similarity between computer and neural organization, there are significant differences between the two. For example, computers do not have structural redundancy, that is where large portions can be removed without impairing its functions. Howerver, the earliest electronic machines were originally developed as special-pourpose computers (SPC) for solving relatively simple problems. These were superseded by the more complex general-purpose computers (GPC) which can solve a large variety of complex problems. This resulted in much greater flexibility, with the result that the GPC's capability far exceeds the demands of various limited problems. Nevertheless, a GPC can solve limited problems with amazing celerity - but at high cost.

Phylogenetically, the rhinencephalon (limbic system) was a primitive mechanism for sensing the world. The simple behavior of the primitive rhinencephalon may be compared with that of the SPC. As the cortex evolved from the ancient brain centers, the simple adaptive responses were integrated into the lower or sub-cortical centers to provide an automatic system for maintaining the vital functioning of the organism-homeostasis. This system was subordinated to the higher cortical centers and may be compared to the GPC. Hypnotic response, however, is strikingly similar to the limited-goal behavior of the SPC. This "regressive" state is in sharp contrast with the logical and highly analytical but generalized mental functioning characteristic of the nonhypnotic states. It is suggested that internal inhibition is the neural mechanism which can be utilized best in sensory processing and control of information exchange. This is a brain mechanism whose detailed understanding in terms of physical models should significantly clarify our conceptions of brain activity and behavior.