Neural and psychological predictors of cognitive enhancement and impairment from neurostimulation

Modulating the temporoparietal junction (TPJ), especially the right counterpart, shows promises in enhancing social cognitive ability. However, it is ambiguous whether the functional lateralization of TPJ determines people’s responsiveness to brain stimulation. Here we investigate this issue with an individual difference approach. Forty-five participants attended three sessions of transcranial direct current stimulation (tDCS) experiments and one neuroimaging session. Our results support the symmetric mechanism of left and right TPJ stimulation. Firstly, the left and right TPJ stimulation effect were comparable in the group-level analysis. Secondly, the individual-level analysis revealed that a less right-lateralized TPJ was associated with a higher level of responsiveness. Participants could be classified into positive responders showing cognitive enhancement and negative responders showing cognitive impairment due to stimulation. The positive responders showed weaker connectivity between bilateral TPJ and the medial prefrontal cortex, which mediated the prediction of offline responsiveness by the lateralization and the social-related trait. Our findings call for a better characterization and predictive models for whom tDCS should be used for, and highlight the necessity and feasibility of pre-stimulation screening.