title: Functional MRI of sleep spindles and K-complexes.
abstract: OBJECTIVE
  Sleep spindles and K-complexes are EEG hallmarks of non-REM sleep. However, the brain regions generating these discharges and the functional connections of their generators to other regions are not fully known. We investigated the neuroanatomical correlates of spindles and K-complexes using simultaneous EEG and fMRI.
  
  
  METHODS
  EEGs recorded during EEG-fMRI studies of 7 individuals were used for fMRI analysis. Higher-level group analyses were performed, and images were thresholded at Z ≥ 2.3.
  
  
  RESULTS
  fMRI of 106 spindles and 60 K-complexes was analyzed. Spindles corresponded to increased signal in thalami and posterior cingulate, and right precuneus, putamen, paracentral cortex, and temporal lobe. K-complexes corresponded to increased signal in thalami, superior temporal lobes, paracentral gyri, and medial regions of the occipital, parietal and frontal lobes. Neither corresponded to regions of decreased signal.
  
  
  CONCLUSIONS
  fMRI of both spindles and K-complexes depicts signal subjacent to the vertex, which likely indicates each discharges' source. The thalamic signal is consistent with thalamic involvement in sleep homeostasis. The limbic region's signal is consistent with roles in memory consolidation. Unlike the spindle, the K-complex corresponds to extensive signal in primary sensory cortices.
  
  
  CONCLUSIONS
  Identification of these active regions contributes to the understanding of sleep networks and the physiology of awareness and memory during sleep.
authors.affiliation: Department of Neurology, Sapienza University of Rome, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Caporro
authors.forename: Zulfi
authors.initials: Z
authors.lastname: Haneef
authors.forename: Hsiang J
authors.initials: HJ
authors.lastname: Yeh
authors.forename: Agatha
authors.initials: A
authors.lastname: Lenartowicz
authors.forename: Carla
authors.initials: C
authors.lastname: Buttinelli
authors.forename: Josef
authors.initials: J
authors.lastname: Parvizi
authors.forename: John M
authors.initials: JM
authors.lastname: Stern
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D012894:Sleep Stages / Q000502:physiology*; D055815:Young Adult