title: Spindle frequency activity in the sleep EEG: individual differences and topographic distribution.
abstract: The brain topography of EEG power spectra in the frequency range of sleep spindles was investigated in 34 sleep recordings from 20 healthy young men. Referential (F3-A2, C3-A2, P3-A2 and O1-A2) and bipolar derivations (F3-C3, C3-P3 and P3-O1) along the anteroposterior axis were used. Sleep spindles gave rise to a distinct peak in the EEG power spectrum. The distribution of the peak frequencies pooled over subjects and derivations showed a bimodal pattern with modes at 11.5 and 13.0 Hz, and a trough at 12.25 Hz. The large inter-subject variation in peak frequency (range: 1.25 Hz) contrasted with the small intra-subject variation between derivations, non-REM sleep episodes and different nights. In some individuals and/or some derivations, only a single spindle peak was present. The topographic distributions from referential and bipolar recordings showed differences. The power showed a declining trend over consecutive non-REM sleep episodes in the low range of spindle frequency activity and a rising trend in the high range. The functional and topographic heterogeneity of sleep spindles in conjunction with the intra-subject stability of their frequency are important characteristics for the analysis of sleep regulation on the basis of the EEG.
authors.affiliation: Institute of Pharmacology, University of Zürich, Switzerland.
authors.forename: E
authors.initials: E
authors.lastname: Werth
authors.forename: P
authors.initials: P
authors.lastname: Achermann
authors.forename: D J
authors.initials: DJ
authors.lastname: Dijk
authors.forename: A A
authors.initials: AA
authors.lastname: Borbély
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology; D004569:Electroencephalography; D006801:Humans; D008297:Male; D012894:Sleep Stages / Q000502:physiology*; D013788:Thalamus / Q000502:physiology