Figure 8.
Polyaxonal amacrine cells selectively suppress OMS ganglion cells. A, Schematic diagram of experiment. Contrast reversal of a grating was used to visually stimulate the retina either alone or synchronous with a depolarizing current pulse (500 pA, 0.5 s) delivered intracellularly to an amacrine cell. Spiking activity from OMS and non-OMS ganglion cells (G) was recorded with a multielectrode array. Responses were analyzed from ganglion cells within 200 μm of the amacrine cell (A). B, C, Results from current injection into a polyaxonal amacrine cell (AC). B, Left, Average firing rate over 30 trials of an OMS ganglion cell (GC) responding to the visual stimulus with and without the current pulse. Trials for the two conditions were interleaved. Right, Fractional inhibition of ganglion cell firing by the current pulse (mean ± SEM, 10 GCs, 3 ACs). C, Left, Same as B for a non-OMS OFF-type ganglion cell. Right, Fractional inhibition of non-OMS ganglion cells (13 GCs, 3 ACs). D, E, Results from current injection into a slow ON–OFF amacrine cell, presented as in B and C. D, Left, OMS ganglion cell light response with and without the current pulse. Right, Fractional inhibition of OMS ganglion cells (10 GCs, 3 ACs). E, Left, Same as D for a non-OMS OFF-type ganglion cell. Right, Fractional inhibition of non-OMS ganglion cells (10 GCs, 3 ACs).