Coding auditory space in the sighted and in the blind individuals

A region in the middle occipito-temporal cortex (hMT+/V5) classically considered as purely visual, enhances its response tuning to moving sounds in case of congenital blindness. However, whether hMT+/V5 contains information about sound directions and whether the impact of this crossmodal reorganization of hMT+/V5 on the regions typically dedicated to auditory motion, like the Planum Temporale (PT) remains equivocal. We used fMRI to characterize the brain activity of sighted and congenital blind individuals listening to left, right, up and down moving and static sounds. Whole-brain univariate analysis revealed preferential auditory motion response in both sighted and blind participants in a dorsal fronto-temporo-parietal network including PT, and in the most anterior portion of hMT+/V5. Blind participants showed additional preferential auditory motion response in the more posterior region of hMT+/V5. Multivariate pattern analysis revealed auditory motion direction information in independently localized PT and hMT+/V5 in blind and sighted participants. However, decoding accuracies in the blind were higher in hMT+/V5 and lower in PT when compared to the sighted. Together, these results suggest that congenital blindness triggers a network-level reorganization that enhances the recruitment of occipital areas in conjunction with a release in the computational workload of temporal regions typically dedicated to spatial hearing