Effects of Electrical Current Applied to Cochlear Partition on Discharges in Individual Auditory-Nerve Fibers. I. Prolonged Direct-Current Polarization
This study is designed to reveal the effects of electrical polarization applied to the cochlear partition on discharges in individual auditory‐nerve fibers in guinea pigs. Direct current is introduced in the basal turn across the organ of Corti. Its effects on the impulse discharges of the primary auditory fibers are measured during systematic variation of electrical and acoustic parameters. Data, recorded on tape, are analyzed by computing latency and interval histograms. With external current flowing from scala vestibuli to scala tympani, the spontaneous activity and sound‐evoked responses increase in most of the auditory‐nerve fibers. Current in the opposite direction causes decrease of impulse discharges. These nerve impulses show adaptation during application of the current and an aftereffect following its offset. It appears that electrical polarization modifies the resting current through the hair cells and also the excitability of the initial segment of the afferent auditory fibers.