title: Source localization of MEG sleep spindles and the relation to sources of alpha band rhythms.
abstract: OBJECTIVE
  First, to determine the distribution of the estimated sources of sleep spindles, and alpha and mu rhythms based on whole-head magnetoencephalogram (MEG) recordings; second, to scrutinize the physiological relevance of the dipole fit algorithm in localizing on-going normal rhythmic activities.
  
  
  METHODS
  One hundred and fifty-one channels were used to record spontaneous MEG activity during wakefulness and superficial sleep in 4 normal subjects. The equivalent dipolar sources were estimated by a new 'dipole fit algorithm' and projected on the corresponding magnetic resonance images.
  
  
  RESULTS
  Equivalent dipoles of MEG spindles were distributed over the centro-parietal region. Those of alpha rhythms were concentrated around the occipito-parietal sulcus and those of mu rhythms were confined to the area around the central sulcus.
  
  
  CONCLUSIONS
  MEG sleep spindles, and alpha and mu rhythms have distinct spatial distributions of their equivalent dipolar sources. This demonstrates that various cortical regions that oscillate within the same frequency band have different spatial organizations and different functional aspects.
authors.affiliation: MEG Center, Vrije Universiteit Medical Center, Polikliniek, receptie C, P.O. Box 7057, 1007 MB, Amsterdam, The Netherlands. i.manshanden@vumc.nl
authors.forename: Ilonka
authors.initials: I
authors.lastname: Manshanden
authors.forename: Jan C
authors.initials: JC
authors.lastname: De Munck
authors.forename: Norman R
authors.initials: NR
authors.lastname: Simon
authors.forename: Fernando H
authors.initials: FH
authors.lastname: Lopes da Silva
mesh_terms: D000328:Adult; D000513:Alpha Rhythm / Q000379:methods* / Q000706:statistics & numerical data; D001921:Brain / Q000502:physiology; D004569:Electroencephalography / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods* / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D012890:Sleep / Q000502:physiology*