The human K-complex represents an isolated cortical down-state.
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.
Cash
Sydney S
SS
Department of Neurology, Epilepsy Division, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA. scash@partners.org
Halgren
Eric
E
Dehghani
Nima
N
Rossetti
Andrea O
AO
Thesen
Thomas
T
Wang
Chunmao
C
Devinsky
Orrin
O
Kuzniecky
Ruben
R
Doyle
Werner
W
Madsen
Joseph R
JR
Bromfield
Edward
E
Eross
Loránd
L
Halász
Péter
P
Karmos
George
G
Csercsa
Richárd
R
Wittner
Lucia
L
Ulbert
István
I
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