[Features of brain biopotentials' spatial organization in adolescents].

Adolescence is characterized by an intensive formation of inter-regional cortical fields interaction, in this period significantly reorganized the activities of deep brain structures and cortical-subcortical interaction are enhanced. Our objectives were to evaluate the nature of changes in the spatial organization of brain bioelectric potentials with age and characteristics of such an organization in adolescents. For this purpose, EEG studies have been conducted in 230 subjects of both sexes aged 4 to 35 years.

[Unusual behaviors in sleep as "compensatory" reactions, aimed at normalizing sleep-alertness cycles].

The present article is an attempt to perform a conceptual clinical and physiological analysis of a large spec- trum of sleep-related phenomena called parasomnias in children, based on data from three independent in- stitutions. Parasonmias appear in the process of falling asleep, at the time of sleep stage changes, and upon awakening. They are common for both healthy children and those with neurological and psychiatric disorders.

["Microcyclic" changes in brain bioelectrical activity during different stages of human natural sleep].

This study presents data on some phasic EEG phenomena regulary recorded during sleep - wakefulness cycle and heterogeneity of EEG sleep stages forming consecutive human sleep macrocycles. These short-term EEG changes quite often tend to periodization, especially during initial sleep-stages and transitive states (sleep microcycles). An attempt was made to reveal EEG microstructures in sleep - wakefulness cycle on the basis of 7 clusters reflecting changes in the biopotential field of the brain represented in n-dimensional factorial space.

[Features of cortex areas system interactions in the left and right brain hemospheres during different human sleep stages].

The article is devoted to analysis of research brain biopotential field structure during different stages of natural night sleep in adults. The special attention is given to distinctions of the spatial organization of EEG interregional relations in the left and right hemispheres which are shown most strongly in the II and III sleep stages. The special role of frontal cortical areas in reorganization of brain system activity during falling asleep is highlighted.

[On factors that effect the variability of central mechanisms of bilingualism].

The article discusses the probable role of many factors that determine the individual variety of neurophysiological mechanisms, which provide the opportunity to learn and free use two or more languages. The formation of a speech functions is affected by both the general factors for bilinguals and monolinguals, as well as the specific characteristic of the situation of bilingualism. The general factors include genetic and environmental impact of explaining the diversity of individual options for the development of morphofunctional organization of speech functions.

[The features of system organization of the brain activity during different sleep stages and transition states].

Electropoligraphical study of the natural night sleep in 16 adults with the use of correlation, coherent, cluster and factor analysis were used to obtain new data describing the active nature of sleep, which is expressed especially in periods of falling asleep and the transition from one stage to another. It is shown that the process of falling asleep and deeper sleep is accompanied by intense reorganization of cortico-subcortical relations, which is reflected in the dynamics ofcrosscorrelation and coherent estimates of interrelations of biopotentials of the brain. The results of factor analysis of multichannel EEG heterogeneity of the transition process from wakefulness to sleep is manifested in significant changes of I, II and III factors weight during I(B) stage of sleep, which may reflect changes in the degree of contribution of the main integrative brain systems in the reorganization of its integral activity.

[Peculiarities of disorders of brain bioelectrical activity spatial-time organization in patients with different consciousness depression after severe head injury].

Specific changes of bioelectrical brain activity was found in 27 patients with different level of posttraumatic consciousness depression by the methods of crosscorrelation, coherence and factor analysis of EEG. The changes of activity of morphofunctional systems of intracerebral integrations were revealed partially by decreasing of unspecific activity from brainstem structures reflected with increasing of slow wave activity and decreasing of EEG coherence in alpha- and beta-range. Depression of system organization of interconnections of bioelectrical brain activity in frontal and occipital regions of both hemispheres was also detected, and testified about decreasing of intercortical and thalamocortical brain system action under brain dislocation.

[About a possible role of parasomnia as a factor of stabilization of sleep cycles].

Cyclical organization of sleep is one of necessary conditions of normal human and animal life activity and one of basic manifestations of the circadian cycle. Transition from the slow-wave to the paradoxical sleep is often accompanied by brief, sometimes rhythmical motor and autonomic reactions that do not cause arousal, but seem to promote activation of the mechanisms providing the "shift" of the sleep phases. Immaturity (or damage) of the neurophysiological mechanisms responsible for the "shift" of the sleep stages leads to hindering of alternation of the sleep phases, which disturbs their normal sequence and leads to deficit of reparative and homeostatic processes; this is manifested in deterioration of the neuropsychical state during wakefulness.

[Analysis of the spatial-temporal EEG organization as the way to the knowledge of neurophysiological mechanisms of the integrative brain activity].

Short results' review of investigations of Laboratory of Neurophysiology of Child of Sechenov Institute is presented in the article. Investigations are based on concept of academic M.N.

[Dominant and reciprocal relationships in the organization of the spatial structure of the biopotential correlations of the brain].

The factor analysis of correlation coefficients of brain potentials spatial-temporal structure revealed the "leading constellations" of neural centers in the coordination system for activity of the human brain hemispheres in resting as well as in functional loads; the reciprocity in organization of potential oscillations in the frontal and occipital brain areas, the reciprocal interrelationships being more obvious in the dominant hemisphere. This factor was shown to depend on the level of activation of the subjects even in a functional state unaltered in respect to other EEG indices. When expecting stimuli demanding a left-hand response, a rearrangement of spontaneous dominant interrelationships to the advantage of the right hemisphere occurs in the EEG.