(A, B) Linear tuning curve areas of the peak (A) inhibitory and (B) excitatory current measured in voltage-clamp recordings. Horizontal line represents median, box boundaries are IQR, and whiskers represent most extreme observation within 1.5× IQR. (C) Ratio of peak excitatory to peak inhibitory current (E/I) for each aligned stimulus direction (mean ± SEM), for cells in which both metrics were measured. 0° is directly superior (for Superior oDSGCs) or inferior (for Inferior oDSGCs) motion. Positive directions are clockwise. Statistical significance for each stimulus direction changes depending on how the tuning curves of Superior and Inferior oDSGCs are aligned (e.g., 180° rotation vs. reflection over the x-axis of the polar tuning curve). In general, E/I of Superior oDSGCs is greater than that of Inferior oDSGCs. (D–AA) For each bar direction, inhibition vs. spikes, excitation vs. spikes, and excitation vs. inhibition for cells in which both metrics were recorded (excitation and inhibition are peak values from voltage-clamp recordings, spikes are counts from cell-attached recordings). Dashed lines are least-squares linear regressions for Superior (magenta) and Inferior (gray) oDSGCs. R and p values are the Spearman’s rank correlation coefficient and associated two-sided significance, respectively. Large points represent univariate means ± SEM for each cell type taken from full data sets (i.e., small dots represent only a subset of cells in which both metrics were recorded, but full univariate datasets also consist of cells in which just one metric was recorded). Directions indicate aligned stimulus directions (as in [C]). For excitation vs. spikes, the fit line for Superior oDSGCs tends to fall below the fit line for Inferior oDSGCs, indicating lower intrinsic excitability. However, greater excitatory inputs to Superior oDSGCs outweigh the difference in intrinsic excitability, leading to more total spikes in Superior oDSGCs. Further, inhibition does not intuitively explain spike outputs since there is a positive correlation between inhibitory input and number of spikes across directions. This correlation is likely caused by an additional positive correlation between excitation and inhibition. Therefore, spikes are best explained by excitation. (BB) Preferred direction of inhibition vs. preferred direction of spikes recorded in the same cell. Dashed line represents the prediction for a 180° difference. (CC) Preferred direction of excitation vs. preferred direction of spikes recorded in the same cell. Dashed line represents prediction for 0° difference. (DD) Preferred direction of excitation vs. preferred direction of inhibition recorded in the same cell. Dashed line represents the prediction for 180° difference. Labels of T, D, N, and V correspond to temporal, dorsal, nasal, and ventral directions on the retina, respectively. *p<0.05, **p<0.01, ***p<0.001.