title: Spatiotemporal Organization and Cross-Frequency Coupling of Sleep Spindles in Primate Cerebral Cortex.
abstract: The sleep spindle has been implicated in thalamic sensory gating, cortical development, and memory consolidation. These multiple functions may depend on specific spatiotemporal emergence and interactions with other spindles and other forms of brain activity. Therefore, we measured sleep spindle cortical distribution, regional heterogeneity, synchronization, and phase relationships with other electroencephalographic components in freely moving primates.
  
  
  
  Transcortical field potentials were recorded from Japanese monkeys via telemetry and were analyzed using the Hilbert-Huang transform.
  
  
  
  Spindle (12-20 Hz) current sources were identified over a wide region of the frontoparietal cortex. Most spindles occurred independently in their own frequency, but some appeared concordant between cortical areas with frequency interdependence, particularly in nearby regions and bilaterally symmetrical regions. Spindles in the dorsolateral prefrontal cortex appeared around the surface-positive and depth-negative phase of transcortically recorded slow oscillations (< 1 Hz), whereas centroparietal spindles emerged around the opposite phase. The slow-oscillation phase reversed between the prefrontal and central regions. Gamma activities increased before spindle onset. Several regional heterogeneities in properties of human spindles were replicated in the monkeys, including frequency, density, and inter-cortical time lags, although their topographic patterns were different from those of humans. The phase-amplitude coupling between spindle and gamma activity was also replicated.
  
  
  
  Spindles in widespread cortical regions are possibly driven by independent rhythm generators, but are temporally associated to spindles in other regions and to slow and gamma oscillations by corticocortical and thalamocortical pathways.
authors.affiliation: Supportive Center for Brain Research, National Institute for Physiological Sciences, Okazaki, Japan.|The Graduate University for Advanced Studies (SOKENDAI), Shonan Village, Hayama, Kanagawa, Japan.
authors.forename: Saori
authors.initials: S
authors.lastname: Takeuchi
authors.affiliation: Supportive Center for Brain Research, National Institute for Physiological Sciences, Okazaki, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Murai
authors.affiliation: McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA.
authors.forename: Hideki
authors.initials: H
authors.lastname: Shimazu
authors.affiliation: Tamagawa University Brain Science Institute, Tokyo, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Isomura
authors.affiliation: Human Brain Research Center, Kyoto University Graduate School of Medicine, Shogoin, Sakyo-ku, Kyoto, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Mima
authors.affiliation: Supportive Center for Brain Research, National Institute for Physiological Sciences, Okazaki, Japan.|The Graduate University for Advanced Studies (SOKENDAI), Shonan Village, Hayama, Kanagawa, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Tsujimoto
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D008251:Macaca / Q000502:physiology*; D008297:Male; D012890:Sleep / Q000502:physiology*
keywords: cortical field potential; gamma oscillations; monkey; non-rapid eye movement sleep; slow wave