Figure 7.

Rod bipolar cell gain and flash-independent noise. A, Current responses of a mouse rod bipolar cell to flashes producing an average of 0.1 Rh*/rod with no background. Flash was delivered at time 0 and was 10 ms in duration. Noise trials were taken from the 300 ms period before the flash, and response trials were taken from the 300 ms period after. Template (thick trace) is the average of 20 responses. Holding potential was −60 mV. Filtered at 100 Hz. B, Responses to flashes producing an average of 0.1 Rh*/rod with a background of 1.3 Rh*/rod/s. Template (thick trace) is the average of 10 responses. C, Dependence of rod bipolar gain on background collected from current (filled circles; N = 23) and voltage (open circles; N = 17) responses. Smooth fit from Equation 5 with m = −1.2 ± 1.3, a = 3.9, b fixed at 3, c = 0.01, and d fixed at 1. Superimposed in gray is the mouse ganglion cell gain. Error bars are SEM. D, Dependence of flash-independent noise on background. Smooth fit from Equation 5 with m fixed at −0.7, a fixed at 16, b fixed at 15, c = 0.07, and d fixed at 0.13.