Control of Vision
C. The Retina
receptive fields of retinal ganglion cells, as shown in Figure
4, are circular and are comprised of two regions, a central,
excitatory one, and a concentric surround region that is typically inhibitory.
As a result of this arrangement, a small spot of light confined to the
center area produces a vigorous response in ganglion cells whereas a larger
spot that impinges on both the center and the surround regions produces
a much reduced response as will be shown later.