Control of Vision
C. The Retina
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.