[EEG frequency: amplitude characteristics at different levels of consciousness]

Relationship was studied between the level of consciousness and the level of the brain activation. State of transition from wakefulness to drowsiness was used as a model of gradual decrease in the level of consciousness. A change in the intensity and quality of appearing involuntarily mental processes served as an index of the level of consciousness as determined by subjects' self-reports. It was found that a certain EEG profile corresponded to each level of consciousness under study. The data obtained showed that the lowest level of activation corresponded to a state in which a subject develops inhibition of "internal speech", "failure of thoughts". In this case, the dynamics of the EEG high frequency rhythm changes was possibly related to the mechanism of transmission of cognitive information.