Cortical reorganization upon peripheral visual loss in Retinitis Pigmentosa A Pereira1, S Ferreira1, B Quendera1, C Mateus1, M D R Almeida2, E Silva3, M Castelo-Branco1 |
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1IBILI, Faculty of Medicine, University of Coimbra, Portugal |
| Retinitis Pigmentosa (RP) is a retinal disease characterized by photoreceptor degeneration. Symptoms are early onset night blindness followed by progressive loss of peripheral vision, and eventually leading to complete blindness. Using MRI we studied the impact of peripheral vision loss on cerebral cortex anatomy. Six patients (two females, 42.8±4.1 yrs) and six age- and gender-matched controls were scanned in a 3T Siemens scanner. Brain cortical thickness (CT) and surface area (SA) of Brodmann areas (BA) were obtained using Freesurfer and exported for statistical analysis with SPSS. Patients’ and controls’ hemispheres (n=12 per group) were compared. Patients’ visual capacity ranged from peripheral visual loss (22º of maximum visual field) to blindness, with loss of central acuity. Disease duration ranged from 20 to 50 years. Visual cortical CT was preserved in patients although BA 18 (secondary visual cortex) showed a tendency for smaller SA (p=0.058). Importantly, patients’ BA4p (primary motor cortex) showed significantly increased CT (p=0.015). Our results suggest a surprising link between peripheral visual loss and motor cortical alterations in RP. These results suggest compensatory motor cortical reorganization triggered by peripheral visual function loss. These results are consistent with peripheral visual sensitivity relevance in vision for action dorsal stream loops. |
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