title: Propofol anesthesia and sleep: a high-density EEG study.
abstract: OBJECTIVE
  The electrophysiological correlates of anesthetic sedation remain poorly understood. We used high-density electroencephalography (hd-EEG) and source modeling to investigate the cortical processes underlying propofol anesthesia and compare them to sleep.
  
  
  METHODS
  256-channel EEG recordings in humans during propofol anesthesia.
  
  
  METHODS
  Hospital operating room.
  
  
  METHODS
  8 healthy subjects (4 males).
  
  
  METHODS
  N/A.
  
  
  RESULTS
  Initially, propofol induced increases in EEG power from 12-25 Hz. Loss of consciousness (LOC) was accompanied by the appearance of EEG slow waves that resembled the slow waves of NREM sleep. We compared slow waves in propofol to slow waves recorded during natural sleep and found that both populations of waves share similar cortical origins and preferentially propagate along the mesial components of the default network. However, propofol slow waves were spatially blurred compared to sleep slow waves and failed to effectively entrain spindle activity. Propofol also caused an increase in gamma (25-40 Hz) power that persisted throughout LOC. Source modeling analysis showed that this increase in gamma power originated from the anterior and posterior cingulate cortices. During LOC, we found increased gamma functional connectivity between these regions compared to the wakefulness.
  
  
  CONCLUSIONS
  Propofol anesthesia is a sleep-like state and slow waves are associated with diminished consciousness even in the presence of high gamma activity.
authors.affiliation: Department of Psychiatry, University of Wisconsin-Madison, Madison, WI 53719, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Murphy
authors.forename: Marie-Aurélie
authors.initials: MA
authors.lastname: Bruno
authors.forename: Brady A
authors.initials: BA
authors.lastname: Riedner
authors.forename: Pierre
authors.initials: P
authors.lastname: Boveroux
authors.forename: Quentin
authors.initials: Q
authors.lastname: Noirhomme
authors.forename: Eric C
authors.initials: EC
authors.lastname: Landsness
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Brichant
authors.forename: Christophe
authors.initials: C
authors.lastname: Phillips
authors.forename: Marcello
authors.initials: M
authors.lastname: Massimini
authors.forename: Steven
authors.initials: S
authors.lastname: Laureys
authors.forename: Giulio
authors.initials: G
authors.lastname: Tononi
authors.forename: Mélanie
authors.initials: M
authors.lastname: Boly
mesh_terms: D000758:Anesthesia; D001921:Brain / Q000187:drug effects / Q000502:physiology; D003243:Consciousness / Q000502:physiology; D004569:Electroencephalography / Q000379:methods; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D008297:Male; D015742:Propofol / Q000494:pharmacology*; D012890:Sleep / Q000502:physiology*; D055815:Young Adult
chemical_list: D006993:Hypnotics and Sedatives; D015742:Propofol