Grouping of MEG gamma oscillations by EEG sleep spindles

► Temporal relationship between EEG sleep spindles and MEG gamma band activity. ► EEG spindles were correlated with power increases in MEG spindle (12.5-15.5 Hz). ► There is strong phase-coupling of gamma band activity with the spindle rhythm. ► Spindles phase-lock gamma band activity by a suppressing mechanism.