title: Hippocampal sleep spindles preceding neocortical sleep onset in humans.
abstract: The coexistence of regionally dissociated brain activity patterns -with some brain areas being active while other already showing sleep signs- may occur throughout all vigilance states including the transition from wakefulness to sleep and may account for both physiological as well as pathological events. These dissociated electrophysiological states are often characterized by multi-domain cognitive and behavioral impairment such as amnesia for events immediately preceding sleep. By performing simultaneous intracerebral electroencephalographic recordings from hippocampal as well as from distributed neocortical sites in neurosurgical patients, we observed that sleep spindles consistently occurred in the hippocampus several minutes before sleep onset. In addition, hippocampal spindle detections consistently preceded neocortical events, with increasing delays along the cortical antero-posterior axis. Our results support the notion that wakefulness and sleep are not mutually exclusive states, but rather part of a continuum resulting from the complex interaction between diffuse neuromodulatory systems and intrinsic properties of the different thalamocortical modules. This interaction may account for the occurrence of dissociated activity across different brain structures characterizing both physiological and pathological conditions.
authors.affiliation: Department of Biomedical and Clinical Sciences "Luigi Sacco", Università degli Studi di Milano, 20157 Milano, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Sarasso
authors.affiliation: Centre of Epilepsy Surgery "C. Munari", Niguarda Hospital, 20162 Milano, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Proserpio
authors.affiliation: Department of Biomedical and Clinical Sciences "Luigi Sacco", Università degli Studi di Milano, 20157 Milano, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Pigorini
authors.affiliation: Department of Psychology, "Sapienza" University of Rome, 00183 Roma, Italy; Department of Psychology, University of Bologna, 40126 Bologna, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Moroni
authors.affiliation: Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Ferrara
authors.affiliation: Department of Psychology, "Sapienza" University of Rome, 00183 Roma, Italy.
authors.forename: L
authors.initials: L
authors.lastname: De Gennaro
authors.affiliation: Institute of Bioimaging and Molecular Physiology, Section of Genoa, National Research Council, 16132 Genova, Italy.
authors.forename: F
authors.initials: F
authors.lastname: De Carli
authors.affiliation: Centre of Epilepsy Surgery "C. Munari", Niguarda Hospital, 20162 Milano, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Lo Russo
authors.affiliation: Department of Biomedical and Clinical Sciences "Luigi Sacco", Università degli Studi di Milano, 20157 Milano, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Massimini
authors.affiliation: Centre of Epilepsy Surgery "C. Munari", Niguarda Hospital, 20162 Milano, Italy; Institute of Bioimaging and Molecular Physiology, Section of Genoa, National Research Council, 16132 Genova, Italy. Electronic address: lino.nobili@ospedaleniguarda.it.
authors.forename: L
authors.initials: L
authors.lastname: Nobili
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000293:Adolescent; D001931:Brain Mapping / Q000379:methods*; D002648:Child; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D008297:Male; D019579:Neocortex / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012894:Sleep Stages / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology*; D055815:Young Adult
keywords: Hippocampus; Sleep spindles; Stereo-EEG; Wake-to-sleep transition