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Giulia Dormal, Franco Lepore, Mona Harissi-Dagher, Armando Bertone, Bruno Rossion, Olivier Collignon; Recovering sight in adulthood leads to rapid neurofunctional reorganization of visual functions. Journal of Vision 2012;12(9):1279. doi: 10.1167/12.9.1279.
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Visual deprivation is associated to crossmodal reorganization, leading to the recruitment of the visual cortex for non-visual processing (Bavelier & Neville, 2002). Because of important advances in visual restoration techniques, a crucial question concerns if, how and at what speed the brain of sight-recovery individuals can re-acquire its function to process visual inputs. We used behavioral measures and functional Magnetic Resonance Imaging (fMRI) to explore the potential neuro-functional modifications taking place in the visual cortex of a low-vision (i.e. legally blind) patient (female, 41) before and after partial vision restoration with Boston keratoprosthesis (Dagher & Dohlman, 2008). Behavioral tasks consisted of computerized tests evaluating visual acuity, contrast sensitivity, face perception and global motion perception. Each fMRI session comprised two runs testing the integrity of a key aspect of the ventral (i.e. face perception) and the dorsal (i.e. motion perception) visual pathways. In order to test for crossmodal reorganization, homologous conditions in the auditory modality were also included (i.e. voices in the ventral run; moving sounds in the dorsal run). The patient was tested 6 days before and 3 days following surgery with identical behavioral and fMRI tasks. In parallel to behavioral improvements, fMRI analyses contrasting differential activations before and after visual restoration revealed massive changes in brain responses. Specifically, we found (1) unspecific activity in the occipital cortex for auditory processing pre-surgery, which was reversed (deactivation) post-surgery; (2) enhanced functional tuning to faces in the right ventral visual pathway (fusiform and occipital "face areas", FFA and OFA) after visual restoration and; (3) reduced responses to motion in V5 bilaterally after visual restoration. These observations provide compelling evidence that the human brain maintains a high degree of plasticity well into adulthood, and that the ventral and dorsal visual pathways might be differently affected by visual deprivation and restoration.
Meeting abstract presented at VSS 2012
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