Abstract:
The processing of somatosensory information in the cortex is often described using body maps, where adjacent cortical regions correspond to adjacent body parts. Additionally, the somatosensory cortex follows a hierarchical structure, which extends from the primary somatosensory cortex (S1) to higher cortical regions. While previous studies have identified multiple body maps and various hierarchy relations, the large-scale organization of these maps and their interactions have been less explored. Using functional MRI with full-body light touch stimulation, we discovered that in S1, body and hierarchy maps are orthogonal, but this orthogonality does not extend to other regions. On a larger scale, both body representation and hierarchy exhibit a radial organization, with a few central extrema governing numerous cortical regions. Similar patterns of radial organization in the visual and auditory systems suggest that radial topography may be a general organizational feature across sensory systems.
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