Figure 8.

AII amacrine cell gain and flash-independent noise. A, Current responses of a mouse AII amacrine cell to a flash producing an average of 0.16 Rh*/rod with no background. Flash was delivered at time 0 and was 10 ms in duration. Noise trials were taken from the 200 ms period before the flash, and response trials were from the 200 ms period after. Template (thick trace) was the average of 28 responses. Holding potential was −60 mV. Filtered at 100 Hz. B, Responses to a flash producing an average of 2.6 Rh*/rod with a background of 1.0 Rh*/rod/s. Template (thick trace) was the average of 26 responses. C, Dependence of AII amacrine cell gain on background. Black circles plot gain for 13 wild-type AII amacrine cells, fit with Equation 5 with exponent m = −0.54 ± 0.04 (mean ± SD), a = 0.001, b fixed at 1.3, c = 21.9, and d fixed at 1. White circles plot gain for 12 connexin36^−/− AII amacrine cells, fit with Equation 5 with m = −0.65 ± 0.15 (mean ± SD), a = 0.04, b fixed at 1.3, c = 4.9, and d fixed at 1. Gray circles plot mouse ganglion cell gain. Error bars are SEM. D, Dependence of flash-independent noise on background for AII amacrine cells from wild-type (filled circles) and connexin36^−/− (open circles) mice. Smooth fit from Equation 5 with m = −0.21, a = 0.13, b fixed at 3, c = 5.8, and d = 0.01.