[The resonance EEG reactions in rhythmical photostimulation and the changes in functional status]

Changes in EEG fine structure in the occipital areas, heart rate, and breath pattern were recorded in 10 male volunteers under photic stimulation with slowly varying frequency in the range of lower or higher EEG alpha-subbands. Self-ratings (on the scale SAN-self-assessment of state of health, activity, and mood) of the functional state, general activity, and mood were obtained before and after stimulation. EEG effects of such photostimulation were represented by the resonance EEG responses of discrete spectral EEG components, frequencies of which periodically coincided with varying rate of flashes. Resonance alpha-enhancement levels depended on the initial individual EEG alpha-voltage and stimulation frequency. Average changes in objective and subjective parameters did not differ between the conditions of lower and higher frequencies of stimulation but were significantly different and of opposite signs when the subjects gave higher and lower self-ratings of positive stimulation effect regardless of the stimulation frequency.