[Dynamics of the EEG spectral power in the frequency band of 1-60 Hz in prestimulus periods at different stages of the cognitive set to facial expression].

Power spectra of cortical potentials in the frequency band of 1-60 Hz were estimated in 29 healthy subjects in the states of rest with the open eyes, after listening to instruction, and in prestimulus periods at the stages of forming and testing of the visual cognitive set to facial expression. Comparative assessment of the power spectra in five frequency bands 2-7, 8-13, 14-20, 21-40 and 41-60 Hz revealed a significant decrease in the power for the frequencies of 1-20 Hz and its parallel increase in the band of 21-60 Hz in all the states under study as compared to the state of rest. At all the set stages, interregional differences in the EEG power were the highest in the bands of 1-20 and 41-60 Hz and the lowest in the band of 14-20 Hz. Significant differences between the "plastic" and "rigid" groups in the power dynamics were observed only at the set-testing stage. Thus, in subjects with the plastic set, the power of the gamma-frequency band was more frequently higher than in subjects with the rigid set.