title: The human K-complex represents an isolated cortical down-state.
abstract: The electroencephalogram (EEG) is a mainstay of clinical neurology and is tightly correlated with brain function, but the specific currents generating human EEG elements remain poorly specified because of a lack of microphysiological recordings. The largest event in healthy human EEGs is the K-complex (KC), which occurs in slow-wave sleep. Here, we show that KCs are generated in widespread cortical areas by outward dendritic currents in the middle and upper cortical layers, accompanied by decreased broadband EEG power and decreased neuronal firing, which demonstrate a steep decline in network activity. Thus, KCs are isolated "down-states," a fundamental cortico-thalamic processing mode already characterized in animals. This correspondence is compatible with proposed contributions of the KC to sleep preservation and memory consolidation.
authors.affiliation: Department of Neurology, Epilepsy Division, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. scash@partners.org
authors.forename: Sydney S
authors.initials: SS
authors.lastname: Cash
authors.forename: Eric
authors.initials: E
authors.lastname: Halgren
authors.forename: Nima
authors.initials: N
authors.lastname: Dehghani
authors.forename: Andrea O
authors.initials: AO
authors.lastname: Rossetti
authors.forename: Thomas
authors.initials: T
authors.lastname: Thesen
authors.forename: Chunmao
authors.initials: C
authors.lastname: Wang
authors.forename: Orrin
authors.initials: O
authors.lastname: Devinsky
authors.forename: Ruben
authors.initials: R
authors.lastname: Kuzniecky
authors.forename: Werner
authors.initials: W
authors.lastname: Doyle
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Madsen
authors.forename: Edward
authors.initials: E
authors.lastname: Bromfield
authors.forename: Loránd
authors.initials: L
authors.lastname: Eross
authors.forename: Péter
authors.initials: P
authors.lastname: Halász
authors.forename: George
authors.initials: G
authors.lastname: Karmos
authors.forename: Richárd
authors.initials: R
authors.lastname: Csercsa
authors.forename: Lucia
authors.initials: L
authors.lastname: Wittner
authors.forename: István
authors.initials: I
authors.lastname: Ulbert
mesh_terms: D000293:Adolescent; D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology*; D004569:Electroencephalography; D055724:Electrophysiological Phenomena; D004827:Epilepsy / Q000503:physiopathology; D005260:Female; D006801:Humans; D008568:Memory; D008875:Middle Aged; D012894:Sleep Stages / Q000502:physiology*; D055815:Young Adult