Fig. 7: Bipolar cell surround properties shape direction selectivity of model starburst amacrine cell.

a Top: ball-and-stick model starburst amacrine cell (SAC), same as in Fig. 6). Bottom: Predicted responses to a moving bar (1000 μm/s) for SAC models using BC RFs with different surround strengths. b Superposition of all BC RFs presynaptic to the Off model at their respective positions along the dendrite at increasing BC surround strengths. c Directional tuning (DSI) of the Off and On SAC dendrite models with input from BCs with different RF surround strengths. d Spatially different motion stimuli used in the simulations: (1) “Single dendrite”: The bar moves along the 150 μm SAC dendrite. (2) “Cell diameter”: The motion path includes an additional 150 μm extension to the left, where the other side of the cell would be located. (3) “Cell surround”: The motion path includes an additional 100 μm extension to the right of the dendrite, so that the bar moves off the end of the dendrite. e DSI of the Off and On SAC models for the different motion stimuli in (m). See also Supplementary Figs. 7 and 10.