title: Influence of anesthesia on cerebral blood flow, cerebral metabolic rate, and brain functional connectivity.
abstract: OBJECTIVE
  To describe recent studies exploring brain function under the influence of hypnotic anesthetic agents, and their implications on the understanding of consciousness physiology and anesthesia-induced alteration of consciousness.
  
  
  RESULTS
  Cerebral cortex is the primary target of the hypnotic effect of anesthetic agents, and higher-order association areas are more sensitive to this effect than lower-order processing regions. Increasing concentration of anesthetic agents progressively attenuates connectivity in the consciousness networks, while connectivity in lower-order sensory and motor networks is preserved. Alteration of thalamic sub-cortical regulation could compromise the cortical integration of information despite preserved thalamic activation by external stimuli. At concentrations producing unresponsiveness, the activity of consciousness networks becomes anticorrelated with thalamic activity, while connectivity in lower-order sensory networks persists, although with cross-modal interaction alterations.
  
  
  CONCLUSIONS
  Accumulating evidence suggests that hypnotic anesthetic agents disrupt large-scale cerebral connectivity. This would result in an inability of the brain to generate and integrate information, while external sensory information is still processed at a lower order of complexity.
authors.affiliation: University Department of Anesthesia and ICM, CHR Citadelle, Belgium. vincent.bonhomme@chu.ulg.ac.be
authors.forename: Vincent
authors.initials: V
authors.lastname: Bonhomme
authors.forename: Pierre
authors.initials: P
authors.lastname: Boveroux
authors.forename: Pol
authors.initials: P
authors.lastname: Hans
authors.forename: Jean François
authors.initials: JF
authors.lastname: Brichant
authors.forename: Audrey
authors.initials: A
authors.lastname: Vanhaudenhuyse
authors.forename: Melanie
authors.initials: M
authors.lastname: Boly
authors.forename: Steven
authors.initials: S
authors.lastname: Laureys
mesh_terms: D000758:Anesthesia; D000777:Anesthetics / Q000494:pharmacology; D001921:Brain / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D001923:Brain Chemistry / Q000187:drug effects*; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D003243:Consciousness / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology; D008279:Magnetic Resonance Imaging; D009434:Neural Pathways / Q000187:drug effects*; D011877:Radionuclide Imaging
chemical_list: D000777:Anesthetics; D006993:Hypnotics and Sedatives