Shared mapping of own and others' bodies in visuotactile bimodal area of monkey parietal cortex.

Parietal cortex contributes to body representations by integrating visual and somatosensory inputs. Because mirror neurons in ventral premotor and parietal cortices represent visual images of others' actions on the intrinsic motor representation of the self, this matching system may play important roles in recognizing actions performed by others. However, where and how the brain represents others' bodies and correlates self and other body representations remain unclear. We expected that a population of visuotactile neurons in simian parietal cortex would represent not only own but others' body parts. We first searched for parietal visuotactile bimodal neurons in the ventral intraparietal area and area 7b of monkeys, and then examined the activity of these neurons while monkeys were observing visual or tactile stimuli placed on the experimenter's body parts. Some bimodal neurons with receptive fields (RFs) anchored on the monkey's body exhibited visual responses matched to corresponding body parts of the experimenter, and visual RFs near that body part existed in the peripersonal space within approximately 30 cm from the body surface. These findings suggest that the brain could use self representation as a reference for perception of others' body parts in parietal cortex. These neurons may contribute to spatial matching between the bodies of the self and others in both action recognition and imitation.