title: Topographical frequency dynamics within EEG and MEG sleep spindles.
abstract: OBJECTIVE
  Spindles are rhythmic bursts of 10-16 Hz activity, lasting ∼1 s, occur during normal stage 2 sleep. Spindles are slower in frontal EEG and possibly MEG. The posterior-fast EEG pattern may predominate early in the spindle, and the anterior-slow pattern late. We aimed to determine the proportion of spindles showing this spatio-spectro-temporal interaction for EEG, and whether it occurs in MEG.
  
  
  METHODS
  We recorded high density EEG and MEG from seven healthy subjects during normal stage 2 sleep. High vs. low frequency (12 vs. 14 Hz) power was measured early vs. late (25th-45th vs. 55th-75th duration percentile) in 183 spindle discharges.
  
  
  RESULTS
  The predicted spatio-spectro-temporal interaction was shown by 48% of EEG and 34% of MEG spindles (chance=25%). Topographically, high frequency EEG power was greatest at midline central contacts, and low frequency power at midline frontal. This frequency-specific topography was fixed over the course of the spindle.
  
  
  CONCLUSIONS
  An evolution from posterior-fast to anterior-slow generators commonly occurs during spindles, and this is visible with EEG and to a lesser extent, MEG.
  
  
  CONCLUSIONS
  The spatio-spectral-temporal evolution of spindles may reflect their possible involvement in coordinating cortical activity during consolidation.
authors.affiliation: Multimodal Imaging Laboratory, Department of Radiology, University of California, San Diego, CA, USA.
authors.forename: Nima
authors.initials: N
authors.lastname: Dehghani
authors.forename: Sydney S
authors.initials: SS
authors.lastname: Cash
authors.forename: Eric
authors.initials: E
authors.lastname: Halgren
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D012894:Sleep Stages / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult