In the frog retina, extracellular recordings of transient ganglion cells have shown that the inhibitory surround of the receptive field of these cells was mediated by gamma-aminobutyric acid and acetylcholine (through the nicotinic receptors). Histoautoradiographic and immunocytochemical studies for the two respectively have shown that these neurotransmitters can act through horizontal and amacrine cells. The separation of the ON and OFF channels mediated by glutamate at the bipolar cell level may also be obtained by glycine and/or acetylcholine (through muscarinic receptors). Respective histoautoradiographic and immunocytochemical studies indicate that these neurotransmitters act at the amacrine cell level. These data are consistent with the functional separation of spatial and temporal organization of retinal information, with horizontal cells especially responsible for the spatial organization of the ganglion cell responses and amacrine cells involved in both spatial and temporal organization of the responses.