Abstract
Age-related macular degeneration (AMD) is a visual pathology that affects the central part of the retina, the macula. It represents the main cause of visual disease and blindness in elderly population. AMD usually leads to the spontaneous development of a preferential retinal locus (PRL) in the spared retina, adopted as a new eccentric fixation point. Because of possible spontaneous plasticity within the cortical regions formerly responding to central vision, it was suggested that peripheral vision, specifically around the PRL, might be different in AMD patients respect to normal subjects. In this study, we used collinear facilitation to test this hypothesis. Five AMD patients (mean age: 72, mean PRL eccentricity: 8°) had to detect the appearance of a Gabor patch (1 cpd, σ = 1°) in their PRL. This patch was co-aligned with a pair of Gabor flankers placed at distances varying between 3° and 8°. A group of age-matched controls was tested at the same eccentricity as the patients' PRLs. The first result of our analysis is that collinear facilitation is consistently present in AMD patients, and emerges at the same target-to-flankers distances as for the control subjects. At a first glance, cortical reorganization would appear marginal in AMD patients; however, we found weaker inhibition at short target-to-flankers distances (mostly 3°) and linearly increasing facilitation for the larger target-to-flankers distances (6° and 8°), hinting toward an overall larger range of facilitation in AMD patients. This pattern of response is a trademark of perceptual learning effects in normal population. Our results therefore demonstrate that AMD patients underwent at least a partial reorganization, possibly induced by spontaneous plasticity. Further studies will evaluate whether perceptual learning can boost neural plasticity in AMD patients.
Meeting abstract presented at VSS 2016