Dissociable Roles Within the Social Brain for Self-Other Processing: A HD-tDCS Study

Theories of right temporoparietal junction (rTPJ) function in social cognition include self-other distinction, self-inhibition, or embodied rotation, whereas the dorsomedial prefrontal cortex (dmPFC) is associated with integrating social information. However, no study has provided causal evidence for dissociable roles of the rTPJ and dmPFC in social cognition. A total of 52 healthy young adults were stratified to receive either dmPFC or rTPJ anodal high-definition transcranial direct current stimulation (HD-tDCS) in a sham-controlled, double-blinded, repeated measures design. Self-other processing was assessed across implicit and explicit level 1 (line-of-sight) and level 2 (mental rotation) visual perspective taking (VPT) tasks, and self-other effects on memory. DmPFC stimulation selectively increased the influence of the allocentric perspective during egocentric perspective taking, indexed by an increase in congruency effect across explicit VPT tasks. Moreover, dmPFC stimulation removed the self-reference effect in episodic memory by increasing the recognition of other and decreasing the recognition of self-encoded words. Stimulation of the rTPJ resulted in improved inhibition of the egocentric-perspective during level 2 VPT only, indexed by a reduction of the congruency effect when taking the allocentric perspective. This research supports theories suggesting that the rTPJ facilitates embodied mental rotation of the self into an alternate perspective, whereas the dmPFC integrates social information relevant to self-directed processes.