IS THE MIRROR NEURON SYSTEM INVOLVED IN WHOLE BODY BIOLOGICAL MOTION PERCEPTUAL ENCODING? A PRELIMINARY TDCS STUDY OVER THE VENTRAL PREMOTOR CORTEX

The perceptual encoding of movements performed by living beings is of fundamental importance in the performance of many biologically relevant behaviors. However, to date, unresolved questions remain about the complex network supporting whole-body biological motion (BM) processing. This study aims to explore the extent to which the mirror neuron system, focusing on the ventral premotor cortex (vPMC), is involved in this cognitive function, hypothesizing a prevalent involvement in the processing of goal-oriented actions. Eleven healthy participants underwent a transcranial direct current stimulation (tDCS) protocol targeting the left vPMC across four sessions: no stimulation, sham stimulation, anodal tDCS, cathodal tDCS. During each session, participants performed a BM discrimination task using point-light displays depicting biological and non-biological movements, which were either goal-oriented or non-goal-oriented. Goal-oriented actions were defined as movements explicitly directed toward an external object or outcome. All stimulation sessions were randomized across participants, and the order of stimulus presentation was randomized within and across experimental conditions. Task performance was assessed in terms of accuracy and reaction times. Anodal tDCS selectively reduced reaction times during the recognition of goal-oriented BM actions, compared with the “no stimulation” condition (p=0.001). No significant effects were observed on accuracy across conditions, nor did cathodal tDCS or sham stimulation produce significant changes in reaction times. These preliminary results show a specific involvement of the vPMC in the perceptual encoding of goal-oriented BM, supporting a task-dependent contribution of mirror neuron system nodes within the broader biological motion network.