The Neural Control of Vision
C. The Retina

Figure 3 depicts the various methods that had been used to assess the response properties of neurons in the retina and other visual structures. Recordings from retinal ganglion cells had been made by lowering microelectrodes onto the retinal surface, by lowering them into the optic nerve, and by dissecting individual fibers from the optic nerve. The dissection method was introduced by the Nobel Laureate Keffer Hartline in the 1930s before the microelectrode was invented. Hartline discovered three major classes of retinal ganglion cells, the ON, the OFF and the ON/OFF. To asses their responses the retina was stimulated either by projecting a beam of light onto the retina directly or by reflecting light from a tangent screen, or, more recently by presenting stimuli on a monitor.