Topographic alignment of auditory inputs to the visual cortex

Abstract

Sensory cortical areas send long-range projections to cortical areas from other sensory modalities, supporting multisensory integration to generate a unified representation of the external world. However, the organizational principles underlying these extensive cross-modal connections remain poorly understood. In this study, we investigated the anatomical and functional organisation of auditory cortex inputs in the visual cortex. We found that populations of anatomically segregated auditory cortex neurons project to different visual cortical areas, broadcasting distinct auditory information to the dorsal and ventral visual processing streams. While sound frequency information was homogenously distributed across visual cortical areas, sound location information was differentially broadcast across the visual cortex. Specifically, sound azimuth and elevation were differentially encoded across visual cortical areas and streams matching the retinotopic bias of the target area. These findings suggest that cross-modal cortico-cortical connections follow a simple rule whereby specialised projection pathways are topographically aligned with the organisational principles of the target sensory area, ensuring spatially coherent integration of multisensory signals.