[The Ability to Successfully Perform Different Kinds of Cognitive Activity Is Reflected in the Topological Features of Intracortical Interactions (Sex Differences in Boys and Girls Aged 5-6 Years)].

We studied the correlation of intellectual development according to The Wechsler Intelligence Scale for Children (WISC test) with the spatial organization of resting EEG in 52 children aged 5-6 years. It was found that the patterns of interregional interactions of different parts of the cortex which correspond with the best performance in the subtests in boys (n = 23) and girls (n = 29) have significant topological differences. In girls, successful subtest performance positively correlated to a greater extent with interhemispheric interactions; in boys--long longitudinal rostral-caudal interactions between various regions of the cortex. The results showed that there are important gender differences in the spatial organization of brain activity associated with the performance of different cognitive activities in preschool children. The successful performance of various subtests by boys required considerable variability in the organization of spatial patterns of interregional interactions; on the contrary, the spatial structure of these patterns in girls was relatively invariable. Obviously, for the successful performance of various cognitive activities at this age in boys, the cortex need to form highly specialized organization of intracortical interactions, while in girls the brain uses relatively similar reorganization of interactions. The data suggest that 5-6-year-old boys and girls use different cognitive strategies when performing the same subtests of the WISC test.

[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. A considerable increase in the I factor weight (reflecting the generalized modulatory brainstem effect on the cortex), along with a decrease in the balance of factors II and III (associated with organization of fronto-occipital and interhemispheric interactions) clearly indicates a special role of sleep synchronizing influences from the brain stem in the development of this initial stage. Reduction of EEG interhemispheric interrelations in the anterior and inferior frontal areas with the deepening of sleep may be indication of the reorganization of the frontal areas activity associated with the coordinated increasing of inactivation process in the cortex of both hemispheres. Degree of stability of the spatial structure of interregional interactions of different brain cortex areas (according to the analysis of average dispersion of crosscorrelation EEG relations) increases on falling asleep with the onset of stage I(A), but with the transition to the stage I(B) there is a significant increase of instability of values EEG crosscorrelation. With the deepening of sleep the subsequent decrease of the dispersion of EEG crosscorrelations in frontal cortex is revealed. During REM sleep the dispersion levels of inter-regional interactions increases as much as possible, especially for EEG crosscorrelations of posterotemporal and inferiofrontal parts of both hemispheres.

[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. On the whole, the obtained data allow believing that with increase of children's age there rises the degree of topological similarity of the spatial structure of systemic interactions of the cortex zones, on which there are "supported" processes of realization of stereognostical and speech functions. Progressing increase with children's age of the degree of similarity of distributive organization of neurophysiological mechanisms of central provision of the speech and stereognosis functions can indicate in favor of concept of correlative formation of these higher psychical functions in postnatal ontogenesis. The obtained results show that the correlative interfunctional interactions promoting progressive development of cognitive functions in the child ontogenesis can be realized through long fiber associated and commissural pathways composing the morphofunctional longitudinal-transversal "skeleton" ofneocortex in the close interaction with thalamo-cortical integrative systems.

[Organisation of the hemisphere interaction in preschool children and in adults during mental speech production and speech perception].

The main goal of this study was to investigate reorganisation of the EEG systemic interactions spatial structure during mental speech production in preschool children: generating sentences from the set of words and generating words from the set of phonemes. In both cases, interhemisphere biopotential relations significantly increased as compared with the baseline (resting with closed eyes). Results of the EEG cross-correlation and coherent analyses showed that during verbal tasks marked intensification of hemisphere interaction was observed. High coefficients of statistic similarity between intercortical interactions patterns in adults and children during sentence and words generating were observed (SC = 0.71 & 0.62 respectively). Opposite to that, lesser coefficients of statistic similarity were observed between these two groups during grammar and semantic mistakes identification (SC < or = 0.50). According to this data we could expect a relatively high maturation level of central mechanisms which underlie the processes of speech production rather than mechanisms which underlie grammar and semantic mistakes identification in preschool children.

[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. Essential strengthening of hemispherical interaction of cortex biopotentials fluctuations during falling asleep--a stage of I(B)--along with its reduction in central and occipital cortical areas is shown during a slow wave sleep (II--IV stage) versus wakefulness.

[Sex differences of spatial-temporal organization of biopotentials of the brain in adults and child 5-6 years old].

Research of topical features of spatial structure of EEG distant relationships has been performed with correlation and coherent analyses of EEG for 26 children of 5-6 years old (12 boys and 14 girls) in comparison to the data at 33 adult subjects (15 men and 18 women). Men have much higher level of EEG intrahemispherical relations of posttemporal and frontal regions of the left hemisphere whereas women have the higher level prevalence of interhemispheric interactions, especially of bilateral-symmetrical arials of both hemispheres. Preschoolers have another character of sex differences in the system organization of inter-regional interactions of brain biopotentials than adults. In particularly the girls have exceeding of EEG distant relations in the same zones of left hemispheres, where at men such relations have exceeding in comparison with woman. The obtained data shows that the pronounced sexual dimorphism of inter-regional interactions of cortical biopotentials at adults and at children is formed, first of all, owing to of EEG distant relations topology differing in males and females subject. Investigation sex differences of spatial-temporal organization of biopotentials of the brain in children can promote forming of more hole and deep understanding of role of sex factor in development of human brain system 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. The changes of integrative brain system activity, provides interhemispheric interaction, had the specific characted. Our results propose a "facilitation" of activity of system, providing "direct" interhemispheric connections through corpus callosum and other commissural tracts of telencephalon as a sequel of mesodiencephalon structures depression with steady reciprocal, antiphase relations of slow weve activity in symmetrical areas of hemispheres in coma II patients. The data of our research had shown no complete disintegration of system brain activity in coma II patients in spite of consciousness and brainstem reflexes depression.

[Characteristics of the EEG spatial organization of the brain neocortex biopotentials in various clinical neurotic depression].

In 20 patients with various clinical variants of neurotic depression, regional organization of the brain bioelectric activity was studied with the aid of cross-correlation, factorial and coherent analyses. Clinical picture of neurotic depression was reflected within the frame of regional organization of the EEG. Regional organization EEG is modified depending on the degree of neurotic depression manifestation and concomitant syndromes of alarm and asthenia. In depressive syndrome without concomitant asthenic and disturbing, the maximum changes are registered in the right fronto-temporal range--left post-temporal areas. In depression and the alarm, depression cross-correlation and coherent communications in fronto-temporal areas of both hemispheres were recorded. In depressive and disturbing syndromes with the asthenic manifestations, depression cross-correlation and coherent communications in fronto-temporal areas of both hemispheres were observed.

[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. This combined pattern is observed both in case of using EEG coherence and correlation analysis. In children interhemispheric EEG relations increasing is appeared already in 5-6 years (maximum in 7-8 yo.), whereas increasing of EEG relations in fronto-occipital direction expanses gradually with age, and only in age 9-10 approaches to definitive level, typical for adults. The data obtained evidence the gradually formation in postnatal ontogenesis of central mechanisms of such important function--stereognosis. Our results suppose that brain mechanisms of right (leading) hand stereognostic activity maturate earlier than left (nonleading) hand activity. Heterochronic involving in stereognostic activity of inter- and intrahemispheric relations can be closely related with gradual and heterochronic processes of commissural and associative hemispheric tracts mielinization.

[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. Livanov about special role of spatial-temporal relations of brain potentials oscillations of various brain areas in providing of functional connection between them. It is shown, that in rest condition the structure of interregional relations of cortex biopotentials in all healthy people is characterized by high spatial orderliness that obviously assists to optimal realization of informational processes during various functional conditions from rest to complex cognitive functions. Special attention is given for the problem of functional signigicance of phase shifts of EEG waves. Data, that allows concluding that brainstem and thalamocartical integrative systems are characterized with relatively small inherited and phenotypic variability whereas fiber systems of both hemispheres that provide processes of intercortical integration are characterized by more expressed inter-individual variability, is presented. Intensive development of long associative and commissural tracks of telencephalon that joined even the most distanced cortical regions of hemispheres in united formation apparently results in formation of morpho-functional "skeleton" of neocortex, that occurred to be the basis for origin of qualitatively new (in comparison to animals) principals of formation of system organization of integral activity of the brain. Existence of long mono- and oligo-synaptic connections provides conditions for correlative develoment in ontogenesis of new function that is not conditioned by phylogenetic development.

Genetic determination of neurophysiological mechanisms of cortical-subcortical integration of bioelectrical brain activity.

The contribution of genetic factors to the formation of the neurophysiological mechanisms of cortical-subcortical integration was studied in 12 pairs of monozygotic and five pairs of dizygotic twins (aged 18-25 years). Intrapair similarity of the nature of spatial interactions between bioelectrical activity in the cerebral cortex, assessed from different combinations of statistical interactions of EEG from 16 monopolar recordings, was assessed in each pair of twins (and among 544 non-related pairs of subjects in both groups). The results suggest a high level of general population invariance and relatively small inherited and phenotypic variability in the morphofunctional systems making up the major neurophysiological mechanisms of brain integration as a whole. The ontogenetic formation of stem and subcortical regulatory structures, which have a leading role in the systems combination of different parts of the brain into a single formation, appears to occur in all individuals by the same principle, as disturbance can apparently affect the fundamental monomorphic features of the species. In turn, we might expect to find large interindividual variability in the establishment of interregional connections of the neocortex, the role of inherited and environmental factors being different in the processes forming long and relatively short intercortical interactions.

[Genetic determination of the neurophysiological mechanisms of the cortico-subcortical integration of bioelectrical activity of the brain]. / Geneticheskaia obuslovlennost' neirofiziologicheskikh mekhanizmov korkovo-podkorkovoi integratsii bioélektricheskoi aktivnosti mozga.

Contribution of genetical factors to neurophysiological mechanisms of cortico-subcortical integration was investigated in 12 pairs of the monozygotic and 5 pairs of dizygotic twins (aged from 18 to 25). In each pair of twins as well as in all 544 unrelated pairs of subjects from both groups, interpairs similarity of the character of the spatial interaction of bioelectrical activity of the neocortex for different combinations of statistical correlations of EEG (from 16 monopolar electrodes) was estimated. The data obtained allow to suggest a higher common population invariance and a relatively small hereditary and phenotypic variability of morphofunctional systems, which underlie neurophysiological mechanisms of the brain integration in general. Apparently, the formation of the brain stem and subcortical regulatory structures in the ontogenesis, the structures that play the main role in the realization of system combination of different parts of the brain into united formation, occurs to all individuals according to a single principle since its disturbance can probably affect the fundamental monomorphal features of the species. In turn, one can expect a great interindividual variability of establishing of the intraregional connections of neocortex, the role of genetic and environmental factors in the formation of short and relatively long interactions being complex.