Dissociable roles for the rTPJ and dmPFC in self-other processing: a HD-tDCS study

Abstract

Background: Social interaction relies on the integration and distinction of self and other. The dorsomedial prefrontal cortex (dmPFC) and the right temporoparietal junction (rTPJ) are two regions consistently associated with social processes. Theories of rTPJ function in social cognition include self--other distinction, self--inhibition, or embodied mental rotation, whereas the dmPFC is associated with a wide range of social functions involving understanding and encoding information pertaining to others. However, to date, no study has provided causal evidence for dissociable roles of the rTPJ and dmPFC in social cognition. Method: 52 healthy young adults were stratified into two studies and received either dmPFC or rTPJ anodal HD--tDCS in a sham--controlled, double--blinded, repeated measures design. Subjects completed a social cognitive battery measuring self--other processing across an implicit and explicit level one (line--of--sight) and level two (mental rotation) visual perspective taking tasks (VPT), as well as self and other encoding effects on episodic memory in order to test the self--reference effect (SRE). Results: Stimulation of the dmPFC selectively enhanced integration of the other perspective into self as indexed by an increase in congruency effect (incongruent--congruent) across both explicit VPT tasks. It also removed the SRE in episodic memory, indexed by increasing the recognition of other--encoded words and reducing the recognition of self--encoded words. Stimulation of the rTPJ resulted in improved inhibition of the self--perspective during level two VPT only, as indexed by a reduction of the congruency effect when taking the other perspective. Conclusion: Our results provide the first causal evidence for dissociable roles of the dmPFC and rTPJ in social cognition. This research supports theories suggesting that rTPJ facilitates embodied mental rotation, whereas the dmPFC integrates information relevant to the other into that of the self.

To the self and beyond: Arousal and functional connectivity of the temporo-parietal junction contributes to spontaneous sensations perception

“…Regions of interest (ROI) in both left and right hemispheres were constructed with the eLORETA given MNI coordinates for the TPJ (54, -48, 7) [18], the EBA (48, -67, 3) [18] and the AI (32,12,20) [77]. A voxel-wise approach was applied and lagged phase synchronization, indexing the physiological lagged connectivity [72] was used to measure the functional connectivity between the TPJ and EBA first, followed by the TPJ and AI.…”

Improving cross-cultural “mind-reading” with electrical brain stimulation

“…Therefore, another possibility is that those with less contact may represent Caucasians more as outgroup members and fail to sufficiently recruit social brain regions such as the dmPFC when inferring mental states. As we have previously identified a role for the dmPFC in the integration of other encoded information into the self (Martin, Dzafic, et al, 2017;Martin et al, 2018), anodal stimulation to the dmPFC in South--East Asian may increase the ability to integrate the mental state of the other into that of the self and improve performance on the RMET.…”

“…The latter renders the stimulation ineffective while preserving blinding integrity (Gbadeyan, Steinhauser, McMahon, & Meinzer, 2016). Details of the stimulation parameters and biophysical modelling evidence for focal current delivery with both set--ups are provided in greater detail in previous manuscripts (Martin, Huang, Hunold, & Meinzer, 2017;Martin, Huang, & Meinzer, 2018). Sessions were at least three days apart to avoid carryover effects.…”

Frequently overlooked realistic moral bioenhancement interventions

“…When participants were asked to pay their own money in return for a specific likelihood of preventing others from experiencing a painful electric shock, anodal mPFC tDCS made them more likely to sacrifice their money given a high probability of preventing others’ pain 19. Anodal tDCS over the dorsomedial PFC has increased cognitive empathy in several studies 20 21. All of these studies and similar examples in the literature22 show promise for using anodal (v)mPFC tDCS as MBE.…”