Fig. 2.

Velocity is linearly represented by charge transfer. (A) Mean EPSC amplitude and weighted decays for EPSCs occurring during baseline and motion in the preferred direction (group 1: cells showing no change, P > 0.05, open circles, n = 13; group 2: showing a significant change, P < 0.05, solid circles; n = 5). (B) (Top to bottom) Velocity stimulus waveform, example current trace and EPSC amplitudes recorded from a group 1 cell plotted over time (n = 31 trials, 1,545 events). (C) Cumulative probability distributions for spontaneous and stimulus-evoked EPSC amplitudes recorded from the cell shown in (B). (Inset) The average EPSCs recorded during baseline (black) and motion in the preferred direction (gray). (D) Average EPSC traces for the same cell over 10°/s velocity bins, aligned on the time scale reporting the average preceding inter-EPSC interval for that velocity bin. Scale bar insert shows time scale for EPSC traces. (E) Population data for average EPSC amplitude recorded at different velocities (n = 13 cells). Data points reflect the mean values obtained from 10°/s velocity bins and are normalized to the average EPSC amplitude observed during baseline. Plot of change in charge transfer from baseline against EPSC frequency (F) and velocity (G) (all calculated over 100 ms bins) from a representative cell.