Propofol and dexmedetomidine sedation share the similar functional activity but distinct functional synchronization

There is insufficient unified research on the effects of propofol and dexmedetomidine on brain functional activity and synchronization. We collected resting-state functional magnetic resonance imaging data from 21 healthy subjects in four different levels of consciousness induced by propofol (awake, mild sedation, deep sedation, and recovery), and other 21 healthy subjects in three different levels of consciousness induced by dexmedetomidine (awake, mild sedation and recovery). The results showed that with the increasing of sedation levels of propofol or dexmedetomidine, fractional amplitude of low-frequency fluctuations and regional homogeneity values decreased in the frontal lobe, while they increased in the superior temporal gyrus and paracentral lobule. Under propofol sedation, functional connectivity (FC) decreased both within and between sensorimotor network and attention network, and within and between the frontoparietal network (FPN) and default mode network (DMN). Simultaneously, a small number of increased connections were observed between the FPN, DMN, and other networks. Under dexmedetomidine sedation, generally decreased FC was observed in the whole brain. This study shows consistent effects on brain functional activity, but distinct impacts on functional synchronization, providing new insights into the understanding of anesthetic mechanisms.