Exploring the Sensorimotor System's Role in Emotional Authenticity Discrimination: A ccPAS Study.

Emotional authenticity discrimination (EAD) is key for social interactions. The social cognition hypothesis suggests that emotion recognition relies on a dynamic visuo-motor interaction. However, the direction and role of this interaction in EAD are still unclear. Here, we investigate the impact of cortico-cortical paired associative stimulation (ccPAS) on the functional connectivity within the visuomotor networks involved in EAD of facial expressions. Sixty-four participants were randomly assigned to different ccPAS conditions targeting the backward and forward connectivity between the right inferior frontal gyrus (IFG) and the right posterior superior temporal sulcus (pSTS; IFG-pSTS, pSTS-IFG), and between the IFG and the right primary motor cortex (M1; IFG-M1, M1-IFG). The results revealed improvements in EAD selectively following the pSTS-IFG and the IFG-M1 modulation, across all emotional expressions. Interestingly, a selective increase for genuine emotions was found after IFG-M1 stimulation, suggesting a specific improvement to ecologically valid and socially relevant stimuli. These findings suggest that selectively enhancing the visual-to-motor and premotor-to-motor pathways facilitates EAD. In contrast, motor-to-visual feedback appears to play a negligible role. This study contributes to understanding the neural mechanisms underlying EAD and highlights the potential role of the ccPAS protocol in improving social cognitive abilities, with implications for developing clinical interventions.