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Résumé
hMT1/V5 is a region in the middle occipitotemporal cortex that responds preferentially to visual motion in sighted people. In cases of early visual deprivation, hMT1/V5 enhances its response to moving sounds. Whether hMT1/V5 contains information about motion directions and whether the functional enhancement observed in the blind is motion specific, or also involves sound source location, remains unsolved. Moreover, the impact of this cross-modal reorganization of hMT1/V5 on the regions typically supporting auditory motion processing, like the human planum temporale (hPT), remains equivocal. We used a combined functional and diffusion-weighted MRI approach and individual in-ear recordings to study the impact of early blindness on the brain networks supporting spatial hearing in male and female humans. Whole-brain univariate analysis revealed that the anterior portion of hMT1/V5 responded to moving sounds in sighted and blind people, while the posterior portion was selective to moving sounds only in blind participants. Multivariate decoding analysis revealed that the presence of motion direction and sound position information was higher in hMT1/V5 and lower in hPT in the blind group. While both groups showed axis-of-motion organization in hMT1/V5 and hPT, this organization was reduced in the hPT of blind people. Diffusion-weighted MRI revealed that the strength of hMT1/V5–hPT connectivity did not differ between groups, whereas the microstructure of the connections was altered by blindness. Our results suggest that the axis-of-motion organization of hMT1/V5 does not depend on visual experience, but that congenital blindness alters the response properties of occipitotemporal networks supporting spatial hearing in the sighted.