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Ceren Battal, Mohamed Rezk, Stefania Mattioni, Roberto Bottini, Giorgia Bertonati, Valeria Occelli, Stefano Targher, Olivier Collignon; Decoding auditory motion direction and location in hMT+/V5 and Planum Temporale of sighted and blind individuals. Journal of Vision 2018;18(10):436. doi: https://doi.org/10.1167/18.10.436.
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In sighted individuals, a portion of the middle occipito-temporal cortex (hMT+/V5) responds preferentially to visual motion whereas the planum temporale (PT) responds preferentially to auditory motion. In case of early visual deprivation, hMT+/V5 enhances its response tuning toward moving sounds but the impact of early blindness on the PT remains elusive. Moreover, whether hMT+/V5 contains sound direction selectivity and whether the reorganization observed in the blind is motion specific or also involves auditory localization is equivocal. We used fMRI to characterize the brain activity of sighted and early blind individuals listening to left, right, up and down moving and static sounds. To create a vivid and ecological sensation of sound location and motion, we used individual in-ear stereo recordings recorded outside the scanner, that were re-played to the participants in the scanner. Whole-brain univariate analysis revealed preferential responses to auditory motion for both sighted and blind participants in a dorsal fronto-temporo-parietal network including PT, as well as a region overlapping with the most anterior portion of hMT+/V5. Blind participants showed additional preferential response in the more posterior region of hMT+/V5. Multivariate pattern analysis revealed significant decoding of auditory motion direction in independently localized PT and hMT+/V5 in blind and sighted participants. However, classification accuracies in the blind were significantly higher in hMT+/V5 and lower in PT when compared to sighted participants. Interestingly, decoding sound location showed a similar pattern of results even if the accuracies were lower than those obtained from motion directions. Together, these results suggest that early blindness triggers enhanced tuning for auditory motion direction and auditory location in hMT+/V5 regions, which occurs in conjunction with a reduced computational involvement of PT. These results shed important lights on how sensory deprivation triggers a network-level reorganization between occipital and temporal regions typically dedicated to a specific function.
Meeting abstract presented at VSS 2018
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