Figure 2.

Visual pathway in a monocular ON/OFF channel model. The retina is composed of arrays of receptors (Image Plane) and ganglion cells (ON Channel Retina and OFF Channel Retina). Each ganglion-cell receptive field has an antagonistic center-surround structure that we model by convolving the images with difference-of-Gaussians filters (ON-center or OFF-center), with the biologically observed 3-to-1 ratio of the radii for the surround to the center (22). The ON and OFF pathways do not interact at the level of the LGN but converge in the cortex.