Suppression of EEG rhythmic frequencies during somato-motor and visuo-motor behavior.

In a previous study of simulated vehicle performance we found that stationary visual attention and body movements alone produced selective effects on topographic EEG frequency patterns. In the present study we focus on an expanded set of these task components. EEG, EOG and ECG data were recorded from 21 subjects during instructed driving movements and during visual scanning tasks ranging from a stationary to a rapidly moving simulated driving display. Spectral analysis was calculated on ten 2-Hz, partially overlapped frequency bands between 6 and 17 Hz. Body movements produced a selective bilateral suppression of 11-15 Hz activity localized to medial somatosensory cortex, while both slow and rapid visual scanning tasks produced a similar bilateral suppression of 11-15 Hz activity localized to temporo-parietal sites. A generalized suppression of 7-11 Hz activity was also found during the fastest visual scanning task. There were no significant differences in ECG between tasks. Other human and animal findings consistent with these functional observations are discussed.