Vicarious Somatotopic Maps Tile Visual Cortex

Our sensory systems work together to generate a cohesive experience of the world around us. Watching others being touched activates brain areas representing our own sense of touch: the visual system recruits touch-related computations to simulate bodily consequences of visual inputs. One long-standing question is how the brain implements this interface between visual and somatosensory representations. To address this question, we developed a method to simultaneously map somatosensory body part tuning and visual field tuning throughout the brain. Applying this method on ongoing co-activations during rest resulted in detailed maps of the body-part tuning in the brains endogenous somatotopic network. During movie watching, somatotopic tuning explains responses throughout the entire dorsolateral visual system, revealing an array of somatotopic body maps that tile the cortical surface. The tuning of these maps aligned with those of visual maps, and predicted both preferences for visual field locations and the visual-category preferences for body parts. These results reveal a mode of brain organization in which aligned visual-somatosensory topographic maps connect visual and bodily reference frames. This cross-modal interface is ideally situated to translate raw sensory impressions into more abstract formats useful for action, social cognition, and semantic processing.