Abstract: Objective To explore the analgesic mechanisms of sufentanil. Methods 17 (8 male, 9 female) healthy right-handed volunteersreceived functional magnetic resonance imaging (fMRI) scan before and after sufentanil 0.2 ng/ml administration respectively. Thalamuswas as the region of interest (ROI). All the processing works were carried out using the Statistical Parametric Mapping. Results Comparedwith the basic state, significantly weaker functional connectivity was mainly found in the region of bilateral rectal gyrus and the left inferiaorbital gyrus of the frontal lobe, while significantly greater functional connectivity was found in bilateral cerebellum, the right cingulategyrus and the left middle temporal gyrus (P<0.001, cluster>13 mm³). Conclusion Thalamus plays a key role in the central analgesia ofsufentanil, which associated with the functional connectivity of bilateral rectal gyrus and the left inferia orbital gyrus of the frontal lobe, bilateralcerebellum, the right cingulate gyrus and the left middle temporal gyrus.

Key words: sufentanil, functional magnetic resonance imaging, functional connectivity, thalamus