Intracellular analysis and structural correlates of the organization of inputs to ganglion cells in the retina of the turtle

Abstract

Intracellular recording from the ganglion cells of the retina of the turtle P. scripta elegans shows the photoresponses are characterized by either of 2 reversal potentials. These were related to the bipolar and amacrine cell inputs to ganglion cells. Of the recorded ganglion cells, 33% (type A) are driven predominantly by 1 type of input, attributed to bipolar cells. Other ganglion cells (66%, type B) receive a mixed input from bipolar and amacrine cells. Type A ganglion cells show a higher conduction velocity (up to 3 m/s) and a higher firing frequency (up to 160 spikes/s) than type B cells. By injecting Procion yellow into bipolar, amacrine and ganglion cells, type A ganglion cells ramified only in those regions of the inner plexiform layer containing cell processes originating exclusively from the bipolar cell type predicted from the recordings. Type B ganglion cells ramify throughout the inner plexiform layer in a multistratified or a diffuse fashion.