title: Breakdown of within- and between-network resting state functional magnetic resonance imaging connectivity during propofol-induced loss of consciousness.
abstract: BACKGROUND
  Mechanisms of anesthesia-induced loss of consciousness remain poorly understood. Resting-state functional magnetic resonance imaging allows investigating whole-brain connectivity changes during pharmacological modulation of the level of consciousness.
  
  
  METHODS
  Low-frequency spontaneous blood oxygen level-dependent fluctuations were measured in 19 healthy volunteers during wakefulness, mild sedation, deep sedation with clinical unconsciousness, and subsequent recovery of consciousness.
  
  
  RESULTS
  Propofol-induced decrease in consciousness linearly correlates with decreased corticocortical and thalamocortical connectivity in frontoparietal networks (i.e., default- and executive-control networks). Furthermore, during propofol-induced unconsciousness, a negative correlation was identified between thalamic and cortical activity in these networks. Finally, negative correlations between default network and lateral frontoparietal cortices activity, present during wakefulness, decreased proportionally to propofol-induced loss of consciousness. In contrast, connectivity was globally preserved in low-level sensory cortices, (i.e., in auditory and visual networks across sedation stages). This was paired with preserved thalamocortical connectivity in these networks. Rather, waning of consciousness was associated with a loss of cross-modal interactions between visual and auditory networks.
  
  
  CONCLUSIONS
  Our results shed light on the functional significance of spontaneous brain activity fluctuations observed in functional magnetic resonance imaging. They suggest that propofol-induced unconsciousness could be linked to a breakdown of cerebral temporal architecture that modifies both within- and between-network connectivity and thus prevents communication between low-level sensory and higher-order frontoparietal cortices, thought to be necessary for perception of external stimuli. They emphasize the importance of thalamocortical connectivity in higher-order cognitive brain networks in the genesis of conscious perception.
authors.affiliation: Department of Anesthesia and Intensive Care Medicine, University of Liège, Liège, Belgium.
authors.forename: Pierre
authors.initials: P
authors.lastname: Boveroux
authors.forename: Audrey
authors.initials: A
authors.lastname: Vanhaudenhuyse
authors.forename: Marie-Aurélie
authors.initials: MA
authors.lastname: Bruno
authors.forename: Quentin
authors.initials: Q
authors.lastname: Noirhomme
authors.forename: Séverine
authors.initials: S
authors.lastname: Lauwick
authors.forename: André
authors.initials: A
authors.lastname: Luxen
authors.forename: Christian
authors.initials: C
authors.lastname: Degueldre
authors.forename: Alain
authors.initials: A
authors.lastname: Plenevaux
authors.forename: Caroline
authors.initials: C
authors.lastname: Schnakers
authors.forename: Christophe
authors.initials: C
authors.lastname: Phillips
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Brichant
authors.forename: Vincent
authors.initials: V
authors.lastname: Bonhomme
authors.forename: Pierre
authors.initials: P
authors.lastname: Maquet
authors.forename: Michael D
authors.initials: MD
authors.lastname: Greicius
authors.forename: Steven
authors.initials: S
authors.lastname: Laureys
authors.forename: Mélanie
authors.initials: M
authors.lastname: Boly
mesh_terms: D000293:Adolescent; D000328:Adult; D016292:Procedural Sedation / Q000379:methods; D003243:Consciousness / Q000187:drug effects* / Q000502:physiology*; D054810:Deep Sedation / Q000379:methods; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009415:Nerve Net / Q000187:drug effects / Q000502:physiology*; D015742:Propofol / Q000494:pharmacology*; D012146:Rest / Q000502:physiology*; D014474:Unconsciousness / Q000139:chemically induced / Q000503:physiopathology; D055815:Young Adult
chemical_list: D015742:Propofol