Centrifugal effects on amacrine cells in the frog's retina

Abstract

The effect of electrical stimulation of the optic nerve on various cells in the frog's retina was investigated by two methods: by the histochemical method (measurement of the amount of RNA in separate cells), and by intracellular recording of potentials. Rhythmic (5 per sec) stimulation of the nerve induced an increase in the amount of RNA in ganglion cells, and especially in amacrine cells. The level of RNA in bipolar and horizontal cells did not change. The results of the experiment indicate that in frogs (as in birds) centrifugal effects are produced through amacrine cells. In electrophysiological experiments reactions to stimulation of the nerve were manifested only in ganglion and amacrine cells. In the ganglion cells that was an antidromic impulse, but sometimes also a delayed impulse, which was evidently the result of secondary excitation of the cell. In amacrine cells the response consisted of a short excitant postsynaptic potential with a discharge of impulses superimposed on it. Data are presented indicating the existence of amacrine cells of different types, probably fulfilling different functions.