Assessment of the Effects of Geomagnetic and Solar Activity on Bioelectrical Processes in the Human Brain Using a Structural Function.

The effects of sharp variations in geomagnetic and solar activity at high latitudes on human brain bioelectrical activity were studied using a multichannel EEG structural function. Studies were performed on 10 healthy men aged 19-37 years. EEG recordings were made daily for 25 days. Solar flares of classes C and M occurred during the study period, as did geomagnetic storms of levels G2-G3. A first-order temporal structural function (SF) in eight-dimensional space was calculated from the EEG. The time scales of internal correlations in the multichannel EEG were assessed using the radius of the correlation of the SF, while the spatial correlational structure of the EEG was assessed in terms of the SF asymptote. Variations in geomagnetic activity were found to be reflected more in changes in the correlation radius than the level of the SF asymptote. Perturbing and modulating effects of geomagnetic and solar activity on SF parameters and the SF spectrum were identified. Thus, the SF of the multichannel EEG can be used to evaluate the integral reaction of the brain as a unified system to the actions of heliogeophysical factors and can be used in studies of the effects of the environment on humans. [ABSTRACT FROM AUTHOR]