The Dynamic DC Potential in the Cochlea of the Guinea Pig (Summating Potential)

Abstract

Using non polarising electrodes, changes of the DC potential in the various turns of the guinea pig's cochlea were measured during the application of sound stimuli by varying the parameters: frequency, intensity and duration. In all turns of the cochlea a distinct change in polarity of the SP was found, when the frequency of the stimulus was varied by a specific amount. The maximum of the +SP corresponds with the tonotopic projections of the experiments of von Békésy. The − SP is found in that part of the cochlea, which is in rest during the application of the sound stimulus. It is argued that the + SP and the − SP are generated in different parts of the organ of Corti. It is found that the latency of the − SP equals the latency of the AP. The + SP starts simultaneously with the CM and has no latency. The explanation is offered that the − SP can be considered as the summated effects of the asynchronous action potentials. The + SP can be considered as the consequence of a leakage current through the organ of Corti in accordance with Davis' supposition, concerning the mechanical sensorial transfer during the movements of the cochlear fluid. This leakage results in the generation of the + SP.