Figure 4.
Gain, noise, and threshold of primate ganglion cells. A, Dependence of gain on background. Collected current responses (mean ± SEM) from eight primate on ganglion cells. Smooth fit from Equation 5 with exponent m = −0.53 ± 0.06 (mean ± SD), a = 0.01, b fixed at 1.3, c = 7.1, and d fixed at 1. Error bars represent SEM. Measurements at backgrounds that differed by <30% were averaged together. Voltage clamped at −60 mV. B, Dependence of flash-independent noise on background. Smooth fit from Equation 5 with parameters a = 4.4, b = 3.7, c fixed at 1, d = 0.004, and m fixed at 0. C, Dependence of flash-dependent noise on background. Smooth fit from Equation 5 with parameters a = 23, b = 27, c = 0.56, d = 0.01, and m = −0.67. D, Dependence of threshold on background. Smooth fit from Equation 6 with M = 0.6 ± 0.1 (mean ± SD), ID = 0.16, and K = 0.02.