Nerve fiber stimulation threshold for multiphase stimuli

Abstract

The authors determined the strength-duration curves for stimulus pulse waveforms of one, two, or three rectangular phases of alternating polarity. Stimuli represented the induced transmembrane current density for a voltage-clamped unmyelinated axon. For any pulse length, the one-phase pulse always required the least current density to cause an action potential, while the two-phase pulse always required the most. For short pulse lengths (/spl tausub mem/, time constant of the resting membrane), the three-phase pulse curve approached that of the two-phase pulse.<>