Propofol Affects Different Human Brain RegionsDepending on Depth of Sedation

Objective To investigate the effect of propofol on brain regions at different sedation levels and theassociation between changes in brain region activity and loss of consciousness using blood oxygenlevel-dependent functional magnetic resonance imaging （BOLD-fMRI） and bispectral index （BIS） monitoring.Methods Forty-eight participants were enrolled at Peking Union Medical College Hospital fromOctober 2011 to March 2012 and randomly assigned to a mild or a deep sedation group using computergeneratedrandom numbers. Preliminary tests were performed a week prior to scanning to determine targeteffect site concentrations based on BIS and concomitant Observer＇s Assessment of Alertness/Sedation scoreswhile under propofol. Within one week of the preliminary tests where propofol dose-response was established,BOLD-fMRI was conducted to examine brain activation with the subject awake, and with propofol infusion atthe sedation level.