Light evoked release of acetylcholine in response to a single flash: cholinergic amacrine cells receive ON and OFF input.

By pharmacologically blocking the inhibitory inputs to the cholinergic amacrine cells of the rabbit retina, we have been able to detect the light-evoked release of ACh in response to a single flash. Under these conditions ACh is released equally at light ON and light OFF. This implies that: the cholinergic amacrine cells receive ON and OFF input; they respond to light with depolarizing transients; and the inputs to this system have a basic symmetry.