EFFECTS OF POLARIZING ELECTRODES ON THE THRESHOLD OF NERVE STIMULATION

Abstract

1) Changes in the threshold of electrical stimulation under the electrodes ofa long polarization were measured by the “superposition method” and the “interruption method.” The measurements were also carried out on a desheathednerve and compared with an ordinary non-desheathed one.
2) By the interruption method one can see evidently that the thresholdslowly increases under the cathode and decreases under the anode during thepolarization and returns slowly to normal after breaking the polarizing current.By the superposition method these changes in the threshold are masked anddistorted by the existence of the polarization potential. The distorting effectsubsides during the polarization, but in anodal polarization this subsidence ofthe effect is of small extent.
3) Between a desheathed and a non-desheathed nerve there can be foundno remarkable difference in the magnitude or the time course of the abovestated changes in the threshold both in the interruption method and in thesuperposition method.
4) These changes in the threshold under both the electrodes are in anopposite direction to those observed in the electrotonus. They should be attributedto some changes in properties of the nerve membrane, such as thepermeability or the polarizability, under the electrodes of a long polarization.If the electrical polarization, whose physiological manifestation is the electrotonus, is considered to be the first effect and the stimulation the second effectof electrode of a polarizing current, then we might name the here observedeffect on the polarizability and excitability of the nerve of a long polarizationas the third effect of the polarizing electrode.