Figure 2.

PST histograms (15 trials) showing the responses of an OFF RGC to light flashes (A), light flashes paired with choline (C), and choline alone (B). In regular Ames medium, the cell responded to 1-second light stimuli with sustained OFF response (black bars). The response to a 1-second application of 1 mM choline (gray bars) was multiphasic and included both enhancement and suppression of firing. Bath application of 3 μM atropine (D–F) resulted in decreases across all conditions, but did not completely eliminate the choline-induced enhancement of the firing rate.