Effect of left temporoparietal transcranial direct current stimulation on self-bias effect and retrospective intentional binding paradigm: A randomised, double-blind, controlled study.

Background: The significance of selection and accelerated perception of self-related sensory information is an established phenomenon termed the self-bias effect. Self-related motor information is utilised by self-other monitoring processes like implicit measures of a sense of agency. Intentional binding is one such process that focuses on the temporal shift between a voluntary action and the sensory consequence. Recently, it was discovered that self-related information from visual stimuli could also affect retrospective intentional binding. Considering the importance of the left temporoparietal junction (l-TPJ) in self-other monitoring, we explored its causal role by modulating its activity with high-definition transcranial direct current stimulation (HD-tDCS). We predicted increased self-associated saliency and intentional binding from anodal HD-tDCS to l-TPJ compared to baseline and cathodal stimulation conditions. Methods: Fifteen healthy right-handed participants performed two computerized tasks: sound-label matching and intentional binding tasks. Behavioural data were collected at baseline and following randomly ordered anodal and cathodal HD-tDCS of l-TPJ. Anodal and cathodal HD-tDCS were administered to all the participants in two different sessions and were separated by at least 72 hours.Results: Strong self-bias effect was observed in all conditions. We didn’t note a retrospective intentional binding effect between self-associated and other-associated sounds in any of the conditions. HD-tDCS indicates a dual and crucial role of l-TPJ in general mismatch detection and other-associated stimulus representation in the self-bias effect.Conclusion: The results suggest a diverse role of l-TPJ in self-reference networks and general mismatch detection.