Affective and instrumental touch dissociate in the social brain network

Interpersonal skin-to-skin touch is an essential channel of communication between caregivers and their infants as well as between adults, increasing cognitive and health benefits. Yet, affective touch as a modality and brain responses to social touch remain under researched. Here, we studied whether our human adult brain interprets affective touch as social based on the communicative intent it carries. In a new fMRI paradigm, participants experienced the same gentle strokes delivered on their forearm in different conditions, goal-directed (GD) and non-goal-directed (NGD) touch. We show that the GD touch elicited greater brain activation in areas known to process action such as the orbitofrontal cortex, whereas the NGD touch elicited greater responses within a specific structural brain network known as the social brain. This network includes, amongst others, areas within the prefrontal cortex, the temporoparietal junction and the insula, all involved in social and emotional processing. These findings suggest that a tactile stimulation on the skin is experienced as social only when it is specifically intended to communicate affection.