Dissociable routes for personal and interpersonal visual enhancement of touch.

Seeing a hand can enhance tactile acuity on the hand, even when tactile stimulation is not visible. This visual enhancement of touch (VET) occurs both when participants see their own hand (personal VET), and when they see another person's hand (interpersonal VET). Interpersonal VET occurs irrespective of where the viewed hand appears, while personal VET is eliminated when visual and proprioceptive signals about the location of one's own hand are incongruent. This suggests that the neural mechanisms for VET may differ according to ownership of the seen hand. We used continuous theta-burst transcranial magnetic stimulation (TMS) to disrupt either the human ventral intraparietal area (hVIP), which integrates tactile, proprioceptive, and visual information about one's own body, or the extrastriate body area (EBA), which processes visual body information irrespective of ownership. Participants then judged the orientation of tactile gratings applied to their hand while viewing images of their own hand, another person's hand, or a non-body object on a screen placed over their actual hand. Disrupting the hVIP attenuated personal VET but did not affect interpersonal VET, suggesting the hVIP is only involved in VET when one's own hand is seen. Disrupting the EBA reduced both personal and interpersonal VET, suggesting it is common to both routes.