Cones, for example, are found primarily in the central portion of the retina, whereas rods are found primarily in the periphery. The receptive field refers to each portion of the retina that when stimulated induces a change in the membrane potential of the nerve cell to which it is attached. The receptive field consists of a central circular area that provides direct photoreceptor input and an encircling area called the receptive field surround. Lateral inhibition occurs when the response of nerve cells to light reaching the center of the receptive field is the opposite to that of light in the surround. This organization of receptors and nerve cells suggests that we see light in terms of local spatial variations rather than as absolute magnitudes of light falling on the retina.
Lateral inhibition occurs in most other sensory systems as well.
In many types of retinas, the color sensitivity of the center of the receptive field is different from that of the receptive field surround. Such an organization of cells creates what is called color opponency. Other retinal receptors and their nerve cells are direction-sensitive and, when probed with spurts of light moving across the retina, produce a burst of impulses at the onset and cessation of illumination. This type of receptive field provides temporal processing of visual information . In one direction, there are alternating columns that receive input from only the left or the right eye.