Fig. 14

Hodgkin–Huxley sodium channel: variance of current and state occupancy. Left: variance of the current $R_k\ast {(V-V_k)}^2$ as a function of voltage V for each reaction k where $V_k=45\text{ mV}$ is the reversal potential for the sodium channel. The magenta curve ($R_{11}=R_{12}$, corresponding to the transitions between state 7 and conducting state 8) has the largest variance in the voltage range $[-100,-25]\text{ mV}$ and the yellow curve ($R_{19}=R_{20}$, corresponding to the transitions between state 4 and conducting state 8) has the largest variance in the voltage range $[-25,100]\text{ mV}$. Right: leading eigenvector components (normalized so that the components sum to 1) as a function of voltage. This shows the probability of being in each state and how that changes with voltage