Fig. 6: Bipolar cell inputs to starburst amacrine cells are radially direction selective and model amacrine cell inherits bipolar cell motion information.

a flex-iGluSnFR was injected into ChAT-cre mice to achieve SAC-specific labeling of glutamate inputs. b The motion preference (d') for all ROIs in an example imaging field showing rDS. “O”, originating; “T”, terminating; “L”, left; “R”, right. For details see Supplementary Fig. 9. c Comparison of rDS velocity tuning curves for On BC clusters identified from mice expressing iGluSnFR only in the SACs (left, ChAT-cre) vs. ubiquitously (right, from Fig. 2). For details see Supplementary Fig. 10. d Up-sampled functional RFs of four BC clusters selected based on co-stratification with SAC-connected BC types. e Ball-and-stick multi-compartment model of a single On SAC dendrite with BC inputs organized according to anatomical and physiological data. f Membrane potential along the dendrite in an Off (top) and On (bottom) SAC model during centrifugal (“CF”) and centripetal (“CP”) motion of a moving bar (20 μm) at 1000 μm/s. g Simulated responses of a distal compartment of the two SAC models for two stimulus velocities (500 and 1000 μm/s) during the motion in (f). h Space-time RFs of individual BCs (top) and their output synapses (red dots) onto a SAC dendrite (black dots: SAC output synapses). The superposition of BC RFs (bottom heatmap) was obtained by summing individual BC RFs, weighted by their number of synapses to the SAC. Proximal BCs are activated by CF motion first and by CP motion last. i Direction selectivity index (DSI) of Off and On SAC model distal compartments at different stimulus velocities. We modeled four different BC input distributions. (1) “Original” (black): BC inputs set based on anatomical and physiological data. (2) “All proximal” (dark gray): replaces distal BC inputs with proximal, for one functional type at all input positions. (3) “All distal” (light gray) replaces proximal BC inputs with distal (4) “Swapped” (blue) assigns the proximal BC type to distal locations and vice versa. See also Supplementary Figs. 7, 9 and 10.