title: Primary visual cortical remapping in patients with inherited peripheral retinal degeneration.
abstract: Human studies addressing the long-term effects of peripheral retinal degeneration on visual cortical function and structure are scarce. Here we investigated this question in patients with Retinitis Pigmentosa (RP), a genetic condition leading to peripheral visual degeneration. We acquired functional and anatomical magnetic resonance data from thirteen patients with different levels of visual loss and twenty-two healthy participants to study primary (V1) visual cortical retinotopic remapping and cortical thickness. We identified systematic visual field remapping in the absence of structural changes in the primary visual cortex of RP patients. Remapping consisted in a retinotopic eccentricity shift of central retinal inputs to more peripheral locations in V1. Importantly, this was associated with changes in visual experience, as assessed by the extent of the visual loss, with more constricted visual fields resulting in larger remapping. This pattern of remapping is consistent with expansion or shifting of neuronal receptive fields into the cortical regions with reduced retinal input. These data provide evidence for functional changes in V1 that are dependent on the magnitude of peripheral visual loss in RP, which may be explained by rapid cortical adaptation mechanisms or long-term cortical reorganization. This study highlights the importance of analyzing the retinal determinants of brain functional and structural alterations for future visual restoration approaches.
authors.affiliation: Visual Neuroscience Laboratory, Institute for Biomedical Imaging and Life Sciences (CNC.IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal.
authors.forename: Sónia
authors.initials: S
authors.lastname: Ferreira
authors.affiliation: Visual Neuroscience Laboratory, Institute for Biomedical Imaging and Life Sciences (CNC.IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal.
authors.forename: Andreia Carvalho
authors.initials: AC
authors.lastname: Pereira
authors.affiliation: Institute of Nuclear Sciences Applied to Health (ICNAS), Brain Imaging Network of Portugal, University of Coimbra, 3000-548 Coimbra, Portugal.
authors.forename: Bruno
authors.initials: B
authors.lastname: Quendera
authors.affiliation: Visual Neuroscience Laboratory, Institute for Biomedical Imaging and Life Sciences (CNC.IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; Ophthalmology Unit, Centro Hospitalar e Universitário de Coimbra (CHUC), 3000-075 Coimbra, Portugal.
authors.forename: Aldina
authors.initials: A
authors.lastname: Reis
authors.affiliation: Visual Neuroscience Laboratory, Institute for Biomedical Imaging and Life Sciences (CNC.IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal.
authors.forename: Eduardo Duarte
authors.initials: ED
authors.lastname: Silva
authors.affiliation: Visual Neuroscience Laboratory, Institute for Biomedical Imaging and Life Sciences (CNC.IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; Institute of Nuclear Sciences Applied to Health (ICNAS), Brain Imaging Network of Portugal, University of Coimbra, 3000-548 Coimbra, Portugal.
authors.forename: Miguel
authors.initials: M
authors.lastname: Castelo-Branco
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012174:Retinitis Pigmentosa / Q000503:physiopathology*; D015354:Vision, Low / Q000503:physiopathology*; D014793:Visual Cortex / Q000503:physiopathology*; D014794:Visual Fields / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: FPZ, Function Projection Zone; Functional magnetic resonance imaging (fMRI); Human; LE, Left Eye; LH, Left Hemisphere; LPZ, Lesion Projection Zone; MRI, Magnetic Resonance Imaging; Plasticity; Primary visual cortex; RE, Right Eye; RH, Right Hemisphere; RNFL, Retinal Nerve Fiber Layer; RP, Retinitis Pigmentosa; Reorganization; Retinitis pigmentosa; Retinotopy; fMRI, functional Magnetic Resonance Imaging