Retinal Dystrophy and Functional Organization of Visual Cortex in Retinitis Pigmentosa S Ferreira1, A Pereira1, 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 an inherited retinal disease characterized by progressive degeneration of photoreceptors and consecutive loss of peripheral vision. This study aims to determine the influence of rod-cone dystrophy on visual cortical function. Brain images from two RP subjects (one female; 43.50±9.19 yr) and four age- and gender-matched controls were acquired with a 3T magnetic resonance scanner and analyzed with BrainVoyager®. BOLD responses resulted from the monocular presentation of a sequence of two checkerboard rings (central and paracentral; maximum diameter of 9.52 degrees), during passive viewing and a one-back task. Visual field diameter was < 23 degrees and corrected visual acuity was > 4/10 for RP subjects. RP subjects showed significant peripheral retinotopic activation in striate and extrastriate visual areas for paracentral rings, between task and passive viewing conditions (p<0.05, uncorrected). Given that rings sequences were equal in both conditions, this difference in activation arose from task demands, not from passive visual stimulation. Results show a functional reorganization of visual cortex in RP subjects, as suggested by previous studies [Poggel et al, 2007, IOVS, 48(5), 935; Masuda et al, 2010, IOVS, 51(10), 5356-5364]. We propose that visual attention boosts activity in peripheral representations under active task demands in RP. |
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