title: Human gamma oscillations during slow wave sleep.
abstract: Neocortical local field potentials have shown that gamma oscillations occur spontaneously during slow-wave sleep (SWS). At the macroscopic EEG level in the human brain, no evidences were reported so far. In this study, by using simultaneous scalp and intracranial EEG recordings in 20 epileptic subjects, we examined gamma oscillations in cerebral cortex during SWS. We report that gamma oscillations in low (30-50 Hz) and high (60-120 Hz) frequency bands recurrently emerged in all investigated regions and their amplitudes coincided with specific phases of the cortical slow wave. In most of the cases, multiple oscillatory bursts in different frequency bands from 30 to 120 Hz were correlated with positive peaks of scalp slow waves ("IN-phase" pattern), confirming previous animal findings. In addition, we report another gamma pattern that appears preferentially during the negative phase of the slow wave ("ANTI-phase" pattern). This new pattern presented dominant peaks in the high gamma range and was preferentially expressed in the temporal cortex. Finally, we found that the spatial coherence between cortical sites exhibiting gamma activities was local and fell off quickly when computed between distant sites. Overall, these results provide the first human evidences that gamma oscillations can be observed in macroscopic EEG recordings during sleep. They support the concept that these high-frequency activities might be associated with phasic increases of neural activity during slow oscillations. Such patterned activity in the sleeping brain could play a role in off-line processing of cortical networks.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale (INSERM) UMRS 975, Centre National de la Recherche Scientifique (CNRS)-UMR 7225, Université Pierre et Marie Curie (UPMC), Hôpital de la Pitié-Salpêtrière, Paris, France.
authors.forename: Mario
authors.initials: M
authors.lastname: Valderrama
authors.forename: Benoît
authors.initials: B
authors.lastname: Crépon
authors.forename: Vicente
authors.initials: V
authors.lastname: Botella-Soler
authors.forename: Jacques
authors.initials: J
authors.lastname: Martinerie
authors.forename: Dominique
authors.initials: D
authors.lastname: Hasboun
authors.forename: Catalina
authors.initials: C
authors.lastname: Alvarado-Rojas
authors.forename: Michel
authors.initials: M
authors.lastname: Baulac
authors.forename: Claude
authors.initials: C
authors.lastname: Adam
authors.forename: Vincent
authors.initials: V
authors.lastname: Navarro
authors.forename: Michel
authors.initials: M
authors.lastname: Le Van Quyen
mesh_terms: D000293:Adolescent; D000328:Adult; D058256:Brain Waves / Q000502:physiology*; D002540:Cerebral Cortex / Q000503:physiopathology*; D004569:Electroencephalography; D004827:Epilepsy / Q000503:physiopathology*; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012890:Sleep / Q000502:physiology*; D055815:Young Adult