Critical involvement of the thalamus and precuneus during restoration of consciousness with @entity2607 in XXXX during @entity1875 anaesthesia: a positron emission tomography study.

@entity2607 @entity1 @entity1875 @entity909
BACKGROUND: Functional brain imaging offers a way to investigate how general anaesthetics impair consciousness. However, functional imaging changes may result from drug effects unrelated to hypnosis. Establishing a causal link with @entity909 is thus difficult. METHODS: To identify changes of neuronal activity functionally linked to the level of consciousness, @entity2607 was used to restore consciousness without changing the anaesthetic concentration in 11 subjects anaesthetized with @entity1875 . Eight subjects (responders) regained consciousness after @entity2607 and three did not (non-responders). Positron emission tomography was used to measure regional cerebral blood flow (rCBF); during baseline (awake), after anaesthesia-induced @entity909 , after @entity2607 administration, and recovery. In addition to subtraction analyses, we used conjunction analysis in the responders to identify changes common to the baseline-anaesthesia and @entity2607 -anaesthesia contrasts. RESULTS: Complete data were available for seven subjects (four responders and three non-responders). The analyses revealed that @entity909 was associated with rCBF decreases in the thalamus and precuneus. Restoration of consciousness by @entity2607 was associated with rCBF increases in these same structures, with the strongest effect in the thalamus. CONCLUSIONS: The results provide strong evidence that reductions in rCBF in the thalamus and precuneus are functionally related to @entity1875 -induced @entity909 independently of any non-specific effects of @entity1875 . These observations confirm that the thalamus and precuneus are key elements to understand how general anaesthetics cause @entity909 and how @entity1 wake up from anaesthesia. Furthermore, they are consistent with the notion that anaesthetic-induced @entity909 is associated with reduced cholinergic activation.
