Figure 1. Convergence in the rod bipolar pathway.

(A) Schematic of the rod bipolar pathway. (B) Estimates of convergence and the light levels in photon absorptions per second (Rh*/s) within the receptive field of each cell at the onset of adaptation. With spatial integration, the number of photons available to control adaptation increases at each stage of processing. Electrical coupling between AII amacrine cells is not depicted but is expected to increase rod input to AII amacrines four fold (Dunn et. al., 2006).