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 facial 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 participants’ faces and strangers’ faces to create four stimuli conditions. After being treated by either OT or placebo (PL), participants reported whether a morphed face resembles themselves, or was morphed with their own faces, 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 OT’s effect on a left hemisphere self network.