Suprathreshold model. A, The voltage dependence of the rms noise is shown for a threefold range of K⁺ channel densities. The leak and slow K⁺ channel densities are varied between (η_leak = 0.006, η_K = 3), (η_leak = 0.012, η_K = 6), and (η_leak = 0.018,η_K = 9) (channels per square micrometer). Noise increases with K⁺ channel density and with depolarization. B, We performed Monte Carlo simulations of a 160 pA depolarizing current pulse injection for 40 msec. Ten trials are shown in the overlap. σ_t indicates the SD of the temporal jitter in the resulting action potential. C, The SD in the time of the spike peak is shown from 20 trials performed at varying amplitude of the 40 msec current pulse. The timing jitter decreases with increasing input current amplitude. The mean spike peak time is plotted in the inset.