AN fibers from BKα^−/− ears show a decrease in saturated discharge rates. A, All rate-versus-level functions for AN fibers with high spontaneous discharge rates (>1 sp/s) are superimposed for BKα^+/+ (black) and BKα^−/− (red) ears. The position of each function along the x-axis is normalized to the model-fit threshold (see Materials and Methods). The “driven rate” (y-axis) is defined as the average discharge rate minus the spontaneous rate. B, Maximum rates are plotted versus SR for all fibers from BKα^−/− and BKα^+/+ ears. Fibers with spontaneous rate of 0 are plotted as 0.05 sp/s. Correspondence between symbol type and genotype is shown in the key. Maximum rates are derived from the model-fit data (see Materials and Methods) and are larger than the driven-rate values in A, because spontaneous rates have not been subtracted out.