Brain structural and functional reorganization due to long term retinal peripheral degeneration in retinitis pigmentosa

Abstract

AbstractPurpose Retinitis Pigmentosa (RP) is a rare retinal disease with progressive degeneration of photoreceptors leading to early peripheral and later central visual loss. It provides a model to analyze visual cortex plasticity since onset age ranges from infancy to adulthood. Prior studies have mostly covered structural or functional alterations in the same cohort; hence we aimed to determine the impact of RP on brain function and structure using magnetic resonance imaging.Methods Brain images of 5 RP subjects (age 37‐66 years, RP duration 6‐42 years) and 10 matched healthy controls were acquired. Retinotopy was used to delineate visual cortical areas. Participants also performed a 1‐back visual task.Results Retinal thickness, visual field, and visual acuity were decreased in RP (p<0.01). Central visual cortex responses were shifted anteriorly into regions usually representing more peripheral locations (p<0.03). Also, V1 and V3 dorsal had higher activation during the task execution (p<0.02). Moreover, cortical thickness was increased in Brodmann areas 7 and 8, and decreased in pericalcarine (p<0.04). Surface area was enlarged in isthmus cingulated, pars orbitalis, and transverse temporal (p<0.02). Caudate volume was also augmented (p=0.01).Conclusion Results suggest brain functional and structural reorganization in RP which is supported by the absence of a silent cortical visual zone, due to unmasking of peripheral responses to central stimuli. Data also suggest top down modulation of attentional higher level regions, and enhanced recruitment of visuospatial orientation mechanisms due to peripheral vision loss. Results are relevant to the development of rehabilitation methods for RP.