[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.

["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.

[Correlative formation of functions as one of mechanisms of functional evolution (by an example of maturation of stereognosis and speech function in child ontogenesis)].

A possibility of correlative formation in ontogenesis of central mechanisms of stereognosis and speech function is considered in the paper by example of comparison of changes in spatial organization of interregional interaction of various cortex areas in children of three ages (5-6, 7-8 and 9-10 years) and in adult examinees during their performances of stereognostical, verbal-mnestical and motor manual activity (tepping-test). With age dynamics of children there is observed a significant increase of the degree of similarity of the spatial structure of EEG interrelations characteristic of periods of performance of stereognostical test with patterns of changes of the EEG distant connections revealed at performance of speech tasks. In turn, the similarity of patterns of interregional EEG relations characteristic of stereognostical tasks with the patterns revealed at the periods of performance of the tepping-test is not increased with age.

[Ontogenetic formation of stereognosis brain mechanism (EEG study)].

In this study the age specificity of inter- and intrahemispheric relations during stereognostic task (tactile identification of predetermined chess-like pieces with right or left hand) in adults and children of 5-6, 7-8 an 9-10 years old is considered. The combined pattern of cortical interactions was revealed in adults. Its appeared in significant increasing (compared to baseline) of interhemispheric EEG relations along with increasing of system interactions of anterior and posterior cortex areas bioelectrical activity.

[Fast positive cortical potentials of the human cerebral hemispheres to visual stimuli evoking saccades].

The EEG was recorded in 7 healthy subjects aged 20-25 years according to the International 10-20 System in the frontal and parietal derivations (F3, F4, Pz, P3, P4) during the saccades related with the visual stimuli. A complex of fast (positive and negative) event-related potentials was recorded in response to visual stimulation before the saccade onset. The amplitude and spatial distribution of these potentials depended on the saccade latency, order of stimuli presentation, personality of a subject etc.