Abstract
Topographic organization is a well-established principle of the human brain, in which adjacent locations in effector and sensory spaces are represented in adjacent positions in the brain. This results in sensorimotor and visual maps ordered according to the layout of the body and visual space, respectively. This topographic organization is not limited to primary sensory and motor cortices, and in fact higher-order visual maps are known to also show responses to stimulation in other modalities, including somatosensation. How, then, are these higher-order maps organized? We hypothesized that multisensory integration is served by overlap and/or alignment of topographic maps of different modalities. Using ultra-high field fMRI we mapped the retinotopic and somatotopic organization of the cerebral cortex performing two distinct tasks, one involving passive visual field mapping, and another involving motor mimicry of facial and limb movements. This allowed us to obtain detailed maps of retinotopic and somatotopic organization in frontal cortex, that show both established and novel body-map reversals in the somatotopic map of M1. Moreover, the resulting visual and motor maps were consistently adjoined, with specific visual field maps aligned with neighboring motor maps of either the face or the hand. We argue that the detailed clustering of sensory and motor modalities in neighboring cortical locations subserves action-perception integration. Our results support the notion that the alignment of multiple topographically organized maps forms an essential processing substrate for multimodal integration during natural visuomotor behaviors.