title: Local Slow Waves in Superficial Layers of Primary Cortical Areas during REM Sleep.
abstract: Sleep is traditionally constituted of two global behavioral states, non-rapid eye movement (NREM) and rapid eye movement (REM), characterized by quiescence and reduced responsiveness to sensory stimuli [1]. NREM sleep is distinguished by slow waves and spindles throughout the cerebral cortex and REM sleep by an "activated," low-voltage fast electroencephalogram (EEG) paradoxically similar to that of wake, accompanied by rapid eye movements and muscle atonia. However, recent evidence has shown that cortical activity patterns during wake and NREM sleep are not as global as previously thought. Local slow waves can appear in various cortical regions in both awake humans [2] and rodents [3-5]. Intracranial recordings in humans [6] and rodents [4, 7] have shown that NREM sleep slow waves most often involve only a subset of brain regions that varies from wave to wave rather than occurring near synchronously across all cortical areas. Moreover, some cortical areas can transiently "wake up" [8] in an otherwise sleeping brain. Yet until now, cortical activity during REM sleep was thought to be homogenously wake-like. We show here, using local laminar recordings in freely moving mice, that slow waves occur regularly during REM sleep, but only in primary sensory and motor areas and mostly in layer 4, the main target of relay thalamic inputs, and layer 3. This finding may help explain why, during REM sleep, we remain disconnected from the environment even though the bulk of the cortex shows wake-like, paradoxical activation.
authors.affiliation: Department of Psychiatry, University of Wisconsin-Madison, 6001 Research Park Boulevard, Madison, WI 53719, USA; Medical Scientist Training Program, University of Wisconsin-Madison, Health Sciences Learning Center, 750 Highland Avenue, Madison, WI 53705, USA; Neuroscience Training Program, University of Wisconsin-Madison, 9531 WIMR II, 1111 Highland Avenue, Madison, WI 53705, USA.
authors.forename: Chadd M
authors.initials: CM
authors.lastname: Funk
authors.affiliation: Department of Psychiatry, University of Wisconsin-Madison, 6001 Research Park Boulevard, Madison, WI 53719, USA.
authors.forename: Sakiko
authors.initials: S
authors.lastname: Honjoh
authors.affiliation: Department of Psychiatry, University of Wisconsin-Madison, 6001 Research Park Boulevard, Madison, WI 53719, USA; Neuroscience Training Program, University of Wisconsin-Madison, 9531 WIMR II, 1111 Highland Avenue, Madison, WI 53705, USA.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Rodriguez
authors.affiliation: Department of Psychiatry, University of Wisconsin-Madison, 6001 Research Park Boulevard, Madison, WI 53719, USA. Electronic address: ccirelli@wisc.edu.
authors.forename: Chiara
authors.initials: C
authors.lastname: Cirelli
authors.affiliation: Department of Psychiatry, University of Wisconsin-Madison, 6001 Research Park Boulevard, Madison, WI 53719, USA. Electronic address: gtononi@wisc.edu.
authors.forename: Giulio
authors.initials: G
authors.lastname: Tononi
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000502:physiology*; D008297:Male; D051379:Mice / Q000502:physiology*; D008810:Mice, Inbred C57BL; D012895:Sleep, REM
keywords: REM sleep; cortical layers; laminar recordings; local sleep