A causal role for inferior parietal lobule in emotion body perception

Recent investigations of emotion body perception have established that perceiving fearful body expressions critically triggers activity in dorsal stream structures related to action preparation. However, the causal contributions of these areas remain unclear. In the current experiment, we addressed this issue using online transcranial magnetic stimulation (TMS) of the inferior parietal lobule (IPL) in the dorsal stream and visual areas (extrastriate body area - EBA in the ventral stream and early visual cortex - EVC). Participants performed a delayed-match-to-sample task requiring detection of a change in posture of body expressions that were either neutral or fearful. Results revealed a significant interaction between the stimulation site and the emotional valence of stimuli, indicating that processing of emotional versus neutral bodies is affected differentially by stimulation of different central areas in body processing. IPL stimulation specifically enhanced fearful body processing. These findings relate emotion processing to separate processing streams, and moreover provide the first evidence that IPL plays a causal role in processing of fearful bodies.