The role of oxytocin in modulating self-other distinction in human brain: a pharmacological fMRI study

The self-other distinction is crucial in human social cognition and social interaction. Studies have found that oxytocin (OT) sharpens the self-other perceptual boundary but with mixed results. Further, little is known if the effect of OT on self-resemblance face perception exists, especially on its neural basis. Moreover, it is unclear if OT would influence the judgment in self-other discrimination when the other is a child or an adult. In the current double-blinded, placebo-controlled study, we investigated the effect of OT on self-face perception at both behavioral and neural levels. We morphed their faces with either an adult, a child, or a stranger face of either an adult or child. After being treated by either OT or placebo (PL), participants reported whether a morphed face resembles themselves while being scanned with fMRI. Behavioral results showed that people judged adult-morphed faces better than child-morphed faces. fMRI results showed that the OT group exhibited generally increased activities in the visual area and IFG for self-morphed faces. Such difference was more pronounced in the adult face compared to child face conditions. Multivariate fMRI analysis revealed that the OT group showed better classification between self-morphed versus other-morphed faces, indicating that OT increased self-other distinction, especially for adult faces and in the left hemisphere. Our study shows the significant effect of OT on self-referential brain processes, providing evidence for the potential OT9s effect on a left hemisphere self network