Propagation of signals from distal dendritic processes. A: voltage responses of an OFF wiry amacrine cell to a black bar (contrast −100%, width 90 μm, height 270 μm, duration 0.5 s) presented either proximally or distally (0.56 mm) to the soma. B: voltage recording from an A1 amacrine cell stimulated with a contrast increment (contrast 100%, duration 0.5 s). C: example spikes from an A1 amacrine cell (AC) and a wiry amacrine cell. D: responses of an ON wiry cell to a white spot centered on the soma (contrast −100%, diameter 0.52 mm, duration 0.5 s) under control conditions, with voltage-gated Na+ (NaV) channels blocked (TTX 0.5 μM), and with NMDA spikes blocked (R-CPP 15 μM, MK-801 10 μM). E: responses of cell in B to a white ring centered on the soma (inner diameter 0.78 mm, outer diameter 0.91 mm). F: peak responses for conditions in E. Spikelets seen under control condition were not suppressed by TTX but were abolished by NMDA receptor antagonists. G: response amplitude to the distal ring relative to the proximal spot for the 3 conditions in D and E averaged across 4 wiry cells and recordings with intracellular MK-801 (1 mM; n = 3 cells) (mean ± SE). H: example spikelets in the same cell under control conditions and with NaV blockade. I: average spikelet across 4 cells for conditions in H. Dashed line indicates the fitted slope during the spikelet's initial rising phase. J and K: spikelet amplitude (J) and initial slope of spikelets (K) across 4 cells for conditions in H. Circles indicate individual cells; error bars indicate SE.