THE RESPONSE OF SINGLE AUDITORY-NERVE FIBERS TO ACOUSTIC STIMULATION

Abstract

THE AIM OF the experiments described here was to study the response of single auditory-nerve fibers to acoustic stimulation delivered to the intact ear. Similar studies on other single afferent fibers have remarkably extended knowledge of the mode of action of diverse sensory mechanisms, while at the same time emphasizing their fundamental similarities. The present report describes the behavior of single auditory fibers and stresses similarities to other sensory nerves; in a subsequent paper we hope to relate these findings to a specific theory of action of the mammalian cochlea. METHOD Young cats anesthetized with dial (0.75 cc. per kilo) were used in these experiments. The postero-dorsal aspect of the auditory nerve was exposed by removing the lateral portion of the occipital bone where it meets the petrous bone. Bleeding from the sinus petrosus inferior was stopped by judicious cauterization or by Clotting Globulin. * A Ringer-filled glass micropipette with Ag-AgCl wire inserted as close as possible to the tip served as the active lead from the nerve. It was early established that pipettes with openings greater than 5~ do not allow isolation of the action potentials of single auditory fibers. The 3 to 5~ electrodes used have an impedance of about 1 megohm when tested on a resistance-capacity bridge between 0.6 and 2.5 kc. The microelectrode and the indifferent electrode (a silver plate in the neck muscles) led to a capacity-coupled amplifier (Grass) with an input done photographically