V.P. Rozhkov - Ph.D. (Biol.), Senior Research Scientist, I.M. Sechenov Institute of Evolutionary Biochemistry and Physiology of Russain Academy of Sciences (St.-Petersburg). E-mail: vlrozhkov@mail.ru S.S. Bekshaev - Ph.D. (Biol.), Senior Research Scientist, I.M.Sechenov Institute of Evolutionary Biochemistry and Physiology of Russain Academy of Sciences (St.-Petersburg). E-mail: beks47@yandex.ru S.I. Soroko - Corresponding-member of RAS, Dr.Sc. (Med.), Professor, Head of Laboratory of Comparative Ecological and Physiological Studies of I.M.Sechenov Institute of Evolutionary Biochemistry and Physiology of Russain Academy of Sciences (St.-Petersburg). E-mail: soroko@iephb.ru

In the North the combined effect of complex natural and social factors may determine the features of cognitive development and may influence on the rate of brain morphogenesis. A special role is played by the identification of the EEG markers that characterize the level of development and qualitative changes in adaptive mechanisms associated with the maturation of the various parts of the brain, including the regulatory structures of the CNS. The results of the analysis of wave structure of the EEG pattern in 86 schoolchildren northerners 7 - 18 years are presented. Conditional probabilities of mutual transitions between the components of EEG referred to 5 frequency bands (delta, theta, alpha-1, alpha-2, beta) were evaluated. The use of the approaches developed in the framework of the theory of graphs and flow in networks permit to reveal markers and identify \"critical\" age when\"algorithm\" interaction of wave components of the EEG is changing. It is shown that these qualitative rearrangements occur at different times for different cortical areas and frequency bands. Based on the observation of the characteristic points, the restructuring of interaction between the functional cores EEG begin and end earlier in the occipital regions of the brain and come with a gradual shift over time to the frontal lobes. The most pronounced qualitative changes in the EEG wave structure during school age are associated with theta and alpha-2 frequency range. The theta range loses the property of the organization \"functional core\" interaction. In children and adolescents living in the North, the restructuring the wave EEG pattern occur at 1.5-2 years later than in the conditions of the middle latitudes. The study showed different rates of maturation of EEG wave component interaction referred to theta frequency range in boys and girls during puberty. The role of individual rhythms in maintenance of the wave structure of EEG pattern and its dynamic rearrangements is considered. The revealed age-related changes of wave structure of EEG patterns reflect some common picture of morphofunctional development of the brain in children and adolescents at different stages of postnatal ontogenesis in severe climatic and socio-economic conditions in the North. This work was financially supported by RHSF in grant № 13-06-00494а.

 

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