title: Breakdown of cortical effective connectivity during sleep.
abstract: When we fall asleep, consciousness fades yet the brain remains active. Why is this so? To investigate whether changes in cortical information transmission play a role, we used transcranial magnetic stimulation together with high-density electroencephalography and asked how the activation of one cortical area (the premotor area) is transmitted to the rest of the brain. During quiet wakefulness, an initial response (approximately 15 milliseconds) at the stimulation site was followed by a sequence of waves that moved to connected cortical areas several centimeters away. During non-rapid eye movement sleep, the initial response was stronger but was rapidly extinguished and did not propagate beyond the stimulation site. Thus, the fading of consciousness during certain stages of sleep may be related to a breakdown in cortical effective connectivity.
authors.affiliation: Department of Psychiatry, University of Wisconsin, Madison, 6001 Research Park Boulevard, Madison, WI 53719, USA.
authors.forename: Marcello
authors.initials: M
authors.lastname: Massimini
authors.forename: Fabio
authors.initials: F
authors.lastname: Ferrarelli
authors.forename: Reto
authors.initials: R
authors.lastname: Huber
authors.forename: Steve K
authors.initials: SK
authors.lastname: Esser
authors.forename: Harpreet
authors.initials: H
authors.lastname: Singh
authors.forename: Giulio
authors.initials: G
authors.lastname: Tononi
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D003198:Computer Simulation; D003243:Consciousness / Q000502:physiology*; D004558:Electric Stimulation; D004569:Electroencephalography; D005071:Evoked Potentials; D006801:Humans; D008280:Magnetics; D008297:Male; D008959:Models, Neurological; D012890:Sleep / Q000502:physiology*; D012984:Software; D014851:Wakefulness / Q000502:physiology