Consciousness and anesthesia.
When we are anesthetized, we expect consciousness to vanish. But does it always? Although anesthesia undoubtedly induces unresponsiveness and amnesia, the extent to which it causes unconsciousness is harder to establish. For instance, certain anesthetics act on areas of the brain's cortex near the midline and abolish behavioral responsiveness, but not necessarily consciousness. Unconsciousness is likely to ensue when a complex of brain regions in the posterior parietal area is inactivated. Consciousness vanishes when anesthetics produce functional disconnection in this posterior complex, interrupting cortical communication and causing a loss of integration; or when they lead to bistable, stereotypic responses, causing a loss of information capacity. Thus, anesthetics seem to cause unconsciousness when they block the brain's ability to integrate information.
Alkire
Michael T
MT
Department of Anesthesiology and the Center for the Neurobiology of Learning and Memory, University of California, Irvine, CA 92868, USA.
Hudetz
Anthony G
AG
Tononi
Giulio
G
D000758:Anesthesia; D000777:Anesthetics / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology*; D003243:Consciousness; D004569:Electroencephalography; D006801:Humans; D008568:Memory / Q000187:drug effects; D008606:Mental Processes / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D012890:Sleep / Q000502:physiology; D013788:Thalamus / Q000187:drug effects / Q000502:physiology*; D014474:Unconsciousness
D000777:Anesthetics