title: Scalp topography of the spontaneous K-complex and of delta-waves in human sleep.
abstract: OBJECTIVE
  Together with spindles, K-complexes are well known hallmarks of stage 2 sleep (S2). However, little is known about their topographical distribution in comparison to delta-waves and to K-complexes superimposed by spindles.
  
  
  METHODS
  In this study, the topographical distribution of spontaneous K-complexes and delta-waves in S2 and delta-waves in stage 4 sleep (S4) in 10 healthy young adults (aged 20 to 35 years, 7 female) was investigated. K-complexes with and without spindles in S2, delta-waves with and without spindles in S2, and delta-waves in S4 distributed all over the night were visually selected. EEG power maps and statistical parametric maps were calculated.
  
  
  RESULTS
  Absolute delta power of S2 K-complexes appeared to be significantly higher than of S2 delta-waves and delta power of S4 delta-waves was higher than of S2 delta-waves. In K-complexes and delta-waves, power was found to be highest over medio-frontal regions in the delta frequency band (0.5-4.0 Hz) with a second maximum occipitally in delta-waves, no matter whether superimposed by a spindle or not.
  
  
  CONCLUSIONS
  K-complexes and delta-waves in S2 differ in topographical distribution. Even though in S2 delta-waves have less power, they have a similar topographical distribution in S2 and S4, supporting the hypothesis that delta-waves in S2 further develop towards delta-waves in slow wave sleep. The delta frequency components of K-complexes and delta-waves are unaffected by spindles.
authors.affiliation: Department of Neurology, University of Vienna, Austria. shappe@gwdg.de
authors.forename: Svenja
authors.initials: S
authors.lastname: Happe
authors.forename: Peter
authors.initials: P
authors.lastname: Anderer
authors.forename: Georg
authors.initials: G
authors.lastname: Gruber
authors.forename: Gerhard
authors.initials: G
authors.lastname: Klösch
authors.forename: Bernd
authors.initials: B
authors.lastname: Saletu
authors.forename: Josef
authors.initials: J
authors.lastname: Zeitlhofer
mesh_terms: D000328:Adult; D001931:Brain Mapping; D003700:Delta Rhythm; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D012535:Scalp; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology