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Tristram Savage, Ione Fine, Fang Jiang; Cross-modal Plasticity After Early Blindness Co-opts Persisting Visual Archetecture.. Journal of Vision 2018;18(10):1226. doi: https://doi.org/10.1167/18.10.1226.
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It is well established that hMT+ shows responses to auditory motion in early blind individuals not seen in sighted controls. Here, we examine whether these auditory responses co-opt residual visual architecture by examining interactions between visual and auditory motion in a sight-recovery subject MM. As a result of early blindness, MM still shows robust cross-modal responses to auditory motion in hMT+. MM acquired vision in adulthood; despite severe losses in acuity, MM has no known deficits in his ability to process visual motion, and shows normal hMT+ responses to visual motion. Methods: In the behavioral task, subjects reported the direction (left/right) of a moving dot field that varied in motion coherence. Simultaneously, we presented a task-irrelevant auditory motion stimulus, whose left/right direction was random with respect to the visual motion direction. Two separate fMRI experiments examined hMT+ responses. (1) Using multivoxel pattern classification, we tested whether visual direction of motion could be classified with an auditory motion training set and vice versa. (2) We compared BOLD univariate responses for 0.5s auditory and visual motion stimuli presented in-phase vs. anti-phase. Results: Behaviorally, the direction of auditory motion biased the perceived direction of visual motion in MM but not controls. Using fMRI, both experiments found evidence for interactions between auditory and visual motion directional responses within hMT+ in MM, but not controls. (1) The direction of auditory motion could be successfully classified based on the pattern of BOLD responses to a visual motion stimulus, and vice versa. (2) BOLD responses were larger when visual and auditory stimuli were presented anti-phase vs in-phase. Thus, the cross-modal plasticity induced by early blindness in area hMT+ seems to be scaffolded upon residual visual motion architecture, and in the case of MM, this seems to have perceptual consequences.
Meeting abstract presented at VSS 2018
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