Electrophysiological and structural studies of the organization of inputs to ganglion cells in the turtle retina.

The structure of electrophysiologically identified bipolar, amacrine and ganglion cells has been studied in the turtle retina. The distribution of these cells processes within the inner plexiform layer (i.p.l.) was evident after intracellular injection of horseradish peroxidase (HRP) or Procion yellow. The observations indicated that ganglion cells may be subdivided into two groups, on the basis of their organization of inputs. Type A ganglion cells receive only bipolar cells inputs, and Type B ganglion cells receive an additional input from amacrine cells. Each of the two groups of ganglion cells performs specific visual functions, like color discrimination or directional sensitivity.