6541 Enhanced Functional Connectivity of the Precuneus in Propofol Sedation

Introduction: The precuneus, along with the adjacent posterior cingulate and retrosplenial cortices, is among the most metabolically active regions of the brain’s default mode network (DMN) in the conscious resting state. The involvement of the precuneus and associative posteromedial parietal structures in memory and consciousness has been supported by a variety of studies. Specifically, the metabolic rate of the precuneus is significantly reduced in suppressed or altered states of consciousness, such as sleep, vegetative state, anesthesia, epilepsy, Alzheimer’s disease, and schizophrenia. Under normal conditions, the precuneus has been proposed to act as a well-connected small-world network hub that functionally links the frontal and parietal regions. However, there has been a lack of understanding of how functional interaction of the precuneus with other regions of the brain is altered during reduced states of consciousness, such as general anesthesia. Given the presumed importance of the precuneus in information integration across the cerebral cortex, here we tested the hypothesis that functional connectivity of the precuneus with the rest of the cortex would be disrupted during anesthetic sedation with propofol. We report that, contrary to our expectation, propofol sedation produced a significant increase in precuneus connectivity with various cortical areas, most prominently with the dorsal prefrontal and visual cortices. These results imply a need for rethinking the functional role of the precuneus in modulating the state of consciousness. An interpretation of the results in the context of a recent proposition for the uncoupling of consciousness, connectedness, and responsiveness in general anesthesia is suggested.