The oxytocinergic system and racial ingroup bias in empathic neural activity

Studies have indicated that the human brain exhibits a more robust neural empathic response towards individuals of the same racial ingroup than those of the outgroup. However, the impact of the oxytocinergic system on the dynamic connectivity between brain regions involved in racial ingroup bias in empathy (RIBE) and its implications for real-life social interaction intention remains unclear. To address this gap, we employed functional magnetic resonance imaging (fMRI) to investigate RIBE-modulated neural activities and the influence of the oxytocinergic system at both neural and behavioral levels. Participants homozygous for the A/A and G/G genotypes of the oxytocin receptor gene (OXTR) rs53576 polymorphism underwent scanning while making judgments about painful versus non-painful stimuli in same-race versus other-race scenarios following either oxytocin (OT) or placebo treatment. The results revealed greater activity in the anterior cingulate cortex (ACC) and anterior insula (AI) in response to same-race compared to other-race models in the G/G group but not in the A/A group. RIBE also modulated the connections between bilateral AI and the ACC, and the effect of OT on this modulatory effect was moderated by genotype rs53576 and interpersonal trust. Moreover, more extensive changes in AI-ACC connections were associated with higher levels of revenge intention in the low interpersonal trust group. Overall, our findings suggest a pivotal role of the oxytocinergic system in the RIBE-modulated neural activities and revenge intention in human interactions with the modulatory effect of interpersonal trust.