Synchronous brain activity during cooperative exchange depends on gender of partner: A fNIRS-based hyperscanning study.

Previous studies have shown that brain activity between partners is synchronized during cooperative exchange. Whether this neural synchronization depends on the gender of partner (i.e., opposite or same to the participant) is open to be explored. In current study, we used functional near-infrared spectroscopy (fNIRS) based hyperscanning to study cooperation in a two-person game (female-female, female-male, and male-male) while assaying brain-to-brain interactions. Cooperation was greater in male-male pairs than in female-female pairs, with intermediate cooperation levels for female-male pairs. More importantly, in dyads with partners with opposite gender (female-male pairs), we found significant task-related cross-brain coherence in frontal regions (i.e., frontopolar cortex, orbitofrontal cortex, and left dorsolateral prefrontal cortex) whereas the cooperation in same gender dyads (female-female pairs and male-male pairs) was not associated with such synchronization. Moreover, the changes of such interbrain coherence across task blocks were significantly correlated with change in degree of cooperation only in mixed-sex dyads. These findings suggested that different neural processes underlie cooperation between mixed-sex and same-sex dyadic interactions.