they soon discovered that at threshold potential, the inward and outward currents, of sodium and potassium ions respectively, were exactly equal and opposite. as opposed to the resting membrane potential, the threshold potential's conditions exhibited a balance of currents that were unstable. instability refers to the fact that any further depolarization activates even more voltage-gated sodium channels, and the incoming sodium depolarizing current overcomes the delayed outward current of potassium. at resting level, on the other hand, the potassium and sodium currents are equal and opposite in a stable manner, where a sudden, continuous flow of ions should not result. the basis is that at a certain level of depolarization, when the currents are equal and opposite in an unstable manner, any further entry of positive charge generates an action potential. this specific value of depolarization (in mv) is otherwise known as the threshold potential.