The Threshold Conditions in Electrical Excitation of the Nerve Fiber. Part I

Abstract

It was stressed that the excitatory state, which is produced by a stimulating current in the nerve fiber and releases a nerve impulse when it rises above a certain definite critical level, does not decay exponentially, as has been assumed in the previous theories, after removal of the current. A brief stimulating current set up an excitatory state which rises first slowly, then quickly and finally reaches a maximum a fraction of a millisecond after termination of the current. After this maximum is reached, it begins to decay (Fig. 4, left).
The time course of the excitatory state was shown to vary, as the course of the stimulating current, in accordance with “the law of proportionality and superposition” (Figs. 1, 2, 6 and 9; equation 10).
Evidence was presented to believe that the law of excitation by long, slowly varying stimulating currents is different from that for short stimulating currents.