This study will use fMRI imaging to examine contradictory findings about the nature and extent of reorganization of the visual cortex following retinal injury.
Research has not demonstrated conclusive answers to several fundamental questions concerning brain plasticity that occurs following retinal injury. Among the questions: How long is needed for substantial visual cortex reorganization? Which visual areas reorganize? Is injury to the periphery less conducive to reorganization than injury to the fovea, which is located in the center of the retina, free of blood vessels, and containing a high concentration of color and light-sensitive cells)? Is training necessary to promote plasticity? What conditions enhance cortical capacity for reorganization?
These researchers hypothesize that: the adult visual cortex is capable of reorganizing after retinal injury; higher visual areas exhibit more extensive reorganization compared to earlier visual areas; foveal injuries result in more extensive reorganization than peripheral retinal injuries; and the degree of reorganization increases with rehabilitative training. They will use fMRI and BOLD imaging to test these hypotheses by mapping the topography of early visual areas and monitoring how it changes in 32 adults with one of five retinal conditions: retinal detachment, retinal artery occlusion, macular degeneration, or ischemic optic neuropathy.
All study participants will have a dense visual field of diminished sight (“scotoma”), which is expected to remain stable throughout the study period. This stability will assure that observed changes in cortical topography are the result of cortical reorganization rather than changes occurring in the retina.
Significance: This carefully controlled, systematic study is anticipated to address several areas of scientific controversy concerning cortical reorganization following retinal injury. The findings are anticipated to help guide vision rehabilitation strategies.