Increased precuneus connectivity during propofol sedation

• The precuneus is known to be involved in memory and consciousness functions.
• Precuneus connectivity unexpectedly increases in the dorsal prefrontal and visual cortices upon loss of response to verbal commands in propofol sedation.
• Changes of posterior cingulate cortex connectivity in sedation are minimal.
• Increased precuneus connectivity in propofol sedation may reflect disconnected endogenous mentation or dreaming that continues at a reduced level of metabolic activity.

Using functional magnetic resonance imaging in human participants, we show that sedation by propofol to the point of lost overt responsiveness during the performance of an auditory verbal memory task unexpectedly increases functional connectivity of the precuneus with cortical regions, particularly the dorsal prefrontal and visual cortices. After recovery of consciousness, functional connectivity returns to a pattern similar to that observed during the wakeful baseline. In the context of a recent proposal that highlights the uncoupling of consciousness, connectedness, and responsiveness in general anesthesia, the increased precuneus functional connectivity under propofol sedation may reflect disconnected endogenous mentation or dreaming that continues at a reduced level of metabolic activity.