The balanced act of crossmodal and intramodal plasticity: Enhanced representation of auditory categories in the occipital cortex of early blind people links to reduced temporal coding

Early visual deprivation triggers enhanced representation of auditory information in the occipital cortex. How does this crossmodal plasticity mechanism impact on the temporal cortex that typically involves in similar auditory coding? To address this question, we used fMRI to characterize brain responses of early blind (EB) and sighted control (SC) individuals listening to sounds from four different categories (human, animal, objects and places). Multivariate pattern analysis was used to decode these four classes of stimuli into individually defined occipital and temporal anatomical parcels. We observed opposite effects of early visual deprivation on auditory decoding in occipital and temporal regions. While occipital regions contained more information about sound categories in the blind, the temporal cortex showed higher decoding in the sighted. Moreover, we observed a negative correlation between occipital and temporal decoding of sound categories in EB, suggesting that these intramodal and crossmodal reorganizations might be inter-connected. Interestingly, we also found that this reorganization process mostly arises in the right hemisphere, which is also the most recruited during the task. We therefore suggest that the extension of non-visual functions in the occipital cortex of EB triggers a network-level reorganization that may reduce the computational load of the regions typically coding for the remaining senses