Characterization of the mu rhythm during rapid eye movement sleep

Objective: The rolandic mu rhythm, a resting activity of somatosensory cort ex, is a striking feature of the waking human electroencephalogram. This st udy will demonstrate that activity with identical features occurs during ra pid eye movement (REM) sleep. Methods: Eye and chin leads were added during prolonged closed circuit tele vision (video) electroencephalographic (EEG) recording with scalp (12 patie nts) or subdural electrodes including 64 contract grids over the frontopari etal cortices (5 patients). Sleep staging was performed by reformatting int o standard polysomnography montages (using two EEG channels, and eye and ch in channels) and applying standard scoring criteria. The recordings were th en reviewed using all EEG channels to assess rhythmic EEG activity by a rea der blinded to the sleep staging. Results: During scalp recordings, 7-10 Hz central rhythms were seen during wakefulness in 7 patients, with 6 of these also having similar rhythms duri ng REM sleep. Similar activity was seen over somatosensory cortex during wa kefulness and REM in all invasively recorded patients. This activity was bl ocked by contralateral body movement or contralateral somatosensory stimuli , even during REM sleep. It was absent in other sleep stages. Conclusions: This REM sleep activity recapitulates all the characteristics of the waking rolandic mu rhythm. This demonstrates functional similarity b etween the states of wakefulness and REM sleep. (C) 2001 Elsevier Science I reland Ltd. All rights reserved.