Temporal interaction of excitation and inhibition (Fitzhugh-Nagumo Model)

"As shown in figure 2 a supra-threshold disturbance triggers an action potential (red, figure 2). Trailing the increase in membrane potential is an increase in the inhibitory current (blue) which reduces the excitability of the cell. As the membrane potential returns to the rest potential, the slower inhibitory current decays to its rest state." (from "Vulnerability of cardiac dynamics," Scholarpedia)

Note that the excitatory action potential (red) spikes, then subsides quickly at the onset of the inhibitory current (blue). As inhibition reaches its peak, the action potential is extinguished. The inhibitory action persists long after the cessation of the action potential.—MK