Abstract
Amblyopia is a developmental visual disorder that affects visual acuity and contrast sensitivity. Many amblyopes also suffer losses on higher-order visual tasks, such as contour integration and form discrimination, the neural bases of which remain unexplained. While neural abnormalities have been found at the level of V1 in amblyopia, it is likely that there are significant processing defects in higher-order visual areas. We recently reported that sensitivity to the higher-order statistics of naturalistic texture images is a signature of processing in area V2 (Freeman, Ziemba et al., 2013). We therefore asked whether amblyopes are poorer at detecting these statistics and whether there is a corresponding neural deficit in V2. We tested 5 amblyopes (4 macaques,1 human) using a spatial 2AFC. They discriminated texture patterns that retain variable amounts of the higher-order statistical structure of original natural images from noise images that retain only the orientation and spatial frequency content. All amblyopes were impaired on the discrimination when viewing with their amblyopic eyes. To investigate whether there was a related neural deficit, we measured neuronal sensitivity to naturalistic structure in 5 amblyopic macaques under anesthesia. We used 96-electrode "Utah" arrays to record multiunit activity and found that V2 sites driven by the amblyopic eye showed a reduced ability to distinguish naturalistic images from their noise counterparts relative to the fellow eye; V1 neural activity was similar for amblyopic and fellow eyes. We conclude that amblyopia modifies the processing of naturalistic visual structure.
Meeting abstract presented at VSS 2016