Seasonal changes of the brain hemodynamics and bioelectrical activity in children and adolescents from the European North

The brain hemodynamics and bioelectrical activity were studied in schoolchildren from the North aged 7–17 years during autumn and spring seasons that distinguished by contrast changes of temperature and light regimes. Seasonal effects upon the brain hemodynamics consist of alterations of blood velocities, tone of cerebral vessels and vasomotor reactivity. EEG changes characterized during spring period by topic-selective increase of spectral power in theta-, alpha- and beta-frequencies in frontal and temporal areas as well as generalized decrease of delta-frequencies that reflected a rise of both activity of the limbic-reticular complex and the brainstem reticular system tone. The low resolution electromagnetic tomography showed the limbic region activation that related to the brain regulatory mechanisms overloading during winter-spring period.