The <i>Sense</i> of Touch: Embodied Simulation in a Visuotactile Mirroring Mechanism for Observed Animate or Inanimate Touch

TLDR

Prior work shows shared neural circuitry in somatosensory cortices for experiencing one's own touch and observing intentional touch. The study aimed to determine whether a visuotactile mirroring mechanism during touch observation is independent of the intentionality of the observed touch. Participants underwent fMRI while viewing video clips of intentional or accidental touch between animate or inanimate objects. The study found overlapping activation in bilateral SII, left IPL/supramarginal gyrus, bilateral temporal‑occipital junction, and left precentral gyrus for all touch observation conditions, but a selective increase in left SI for intentional touch that correlated with perceived intentionality, suggesting that the visuotactile mirroring mechanism supports an abstract notion of touch while SI reflects resonance with intentional agents.

Abstract

Abstract Previous studies have shown a shared neural circuitry in the somatosensory cortices for the experience of one's own body being touched and the sight of intentional touch. Using functional magnetic resonance imaging (fMRI), the present study aimed to elucidate whether the activation of a visuotactile mirroring mechanism during touch observation applies to the sight of any touch, that is, whether it is independent of the intentionality of observed touching agent. During fMRI scanning, healthy participants viewed video clips depicting a touch that was intentional or accidental, and occurring between animate or inanimate objects. Analyses showed equal overlapping activation for all the touch observation conditions and the experience of one's own body being touched in the bilateral secondary somatosensory cortex (SII), left inferior parietal lobule (IPL)/supramarginal gyrus, bilateral temporal-occipital junction, and left precentral gyrus. A significant difference between the sight of an intentional touch, compared to an accidental touch, was found in the left primary somatosensory cortex (SI/Brodmann's area [BA] 2). Interestingly, activation in SI/BA 2 significantly correlated with the degree of intentionality of the observed touch stimuli as rated by participants. Our findings show that activation of a visuotactile mirroring mechanism for touch observation might underpin an abstract notion of touch, whereas activation in SI might reflect a human tendency to “resonate” more with a present or assumed intentional touching agent.