Brain topography of the human sleep EEG: antero-posterior shifts of spectral power.

To investigate the brain topography of the human sleep EEG along the antero-posterior axis, spectra (0.25-25 Hz; 1 Hz bins) were computed from all-night EEG recordings (n = 20 subjects) obtained from an anterior F3-C3) and a posterior (P3-O1) derivation. State-dependent and frequency-dependent topographic differences were observed. In non-rapid eye movement (REM) sleep, power in the anterior derivation was higher than in the posterior derivation in the 2 Hz bin, and lower in the 4-10 Hz bins. In REM sleep, a posterior dominance was present in most bins below 18 Hz. The 2-6 Hz bins exhibited an antero-posterior shift of power over consecutive non-REM sleep episodes. Consistent shifts of power were also present within non-REM sleep episodes. The results suggest that anterior and posterior cortical regions may be differently involved in the sleep process.