Fig. 1.

Schematic diagram of linking the RGC density to psychophysically defined areas of spatial integration. The extent of spatial integration for visual recognition increases with retinal eccentricity. Like acuity thresholds (52), this eccentricity-dependent increase in the extent of spatial integration has been explained by cortical magnification (i.e., millimeter of cortex per degree of visual field decreases as a function of eccentricity) (14, 33). However, the topographic distribution of the RGC density to a large extent may govern cortical representation of the visual field as cortical projections of RGCs become uniformly distributed throughout the early visual cortical area V1 (99). Here we relate the variation in the RGC density directly to the variation in the extent of spatial integration across the visual field.