Vicarious body maps bridge vision and touch in the human brain
Publication date: 26/11/2025
Authors: Hedger N., Naselaris T., Kay K. & Knapen T.
Journal: Nature
Commentary: This study investigates the neural mechanisms that integrate visual and somatosensory information in the human brain. Specifically, it addresses how observing bodily events recruits tactile representations, a phenomenon central to vicarious perception and embodied cognition. The authors introduce a dual-source connective-field modelling framework that simultaneously estimates retinotopic tuning from primary visual cortex (V1) and somatotopic tuning from primary somatosensory cortex (S1), allowing whole-brain mapping of visual–somatosensory topographic organization. Using ultra-high-field (7 T) functional MRI data from 174 participants, the model was applied to both resting-state activity and naturalistic video viewing. During rest, the approach revealed extensive intrinsic somatotopic organization beyond classical somatosensory regions, encompassing parietal, frontal, medial, and insular cortices. These endogenous maps recapitulated known somatotopic gradients and body-part biases, demonstrating that structured body representations persist in the absence of external sensorimotor input. During video viewing, somatotopic connectivity markedly expanded into the visual system, particularly within dorsal and lateral visual cortices. In these regions, neural responses were best explained by a combination of somatosensory and visual tuning, indicating genuine multimodal processing rather than purely visual encoding. The authors identified multiple somatotopic maps tiling dorsolateral visual cortex, with tuning aligned to visual field location dorsally and to visual body-part category ventrally. Notably, somatotopic tuning predicted visual selectivity for specific body parts in regions such as the extrastriate and fusiform body areas. Collectively, the findings reveal a previously unrecognized organizational principle in which aligned visual and somatosensory maps provide a common reference frame for perception. This cross-modal topographic architecture offers a neural substrate for embodied visual experience, vicarious sensation, and the integration of perception with action, social cognition, and semantic processing.
Commented by: Cecilia Steinwurzel
DOI: https://doi.org/10.1038/s41586-025-09796-0
