Robert Sanders photo Over a period of nearly three years, Roska painstakingly measured signals from more than 200 ganglion cells in the rabbit retina as he flashed pictures of a featureless square or circle.
Ganglion cells are the eye's output cells, forming the optic nerve connecting it to the brain.
From these, he and Werblin determined that there are about a dozen different populations of ganglion cells, each spanning the full visual space and producing a different movie output. One group of ganglion cells, for example, only sends signals when it detects a moving edge. Another group fires only after a stimulus stops. Another sees large uniform areas, yet another only the area surrounding a figure. The two researchers shared these detailed findings with software designer David Balya in Hungary, who modeled the visual processing on a computer, a preliminary step before actually programming a CNN chip to simulate the image processing that goes on in the eye.