layer of ganglion cells

The first thing the light hits is, in fact, the layer of ganglion cells which constitute the "electronic interface" between the photocells and the brain.

It has a diameter of around 1.5 mm and is often histologically defined as having two or more layers of ganglion cells.

His is credited with the discovery of Plexus myentericus Auerbachi, or Auerbach's plexus, a layer of ganglion cells that provide control of movements of the gastro-intestinal tract.