Latency of Action Potentials in the Cochlea of the Guinea Pig

Abstract

The latency of the well-synchronized whole-nerve action potential in the cochlea of the guinea pig includes both neural and traveling-wave delays. The latency varies with the intensity and with the frequency of the acoustic stimulus. Selective local interference with the response was produced by: (1) selective masking, (2) local fatigue of sensory elements, and (3) local injection of drugs. Such interference in the basal turn prolonged the latency. Low-frequency tones reduced the N1 response to click stimuli without changing the modal latency. Apparently nearly all of the well-synchronized action potential is due to neurons that arise in the 1st turn of the cochlea. The traveling-wave delay appears as a significant component of latency only in smaller responses that remain after the impulses arising in the 1st turn are suppressed. Information about the time of onset of an acoustic signal can be delivered to the central nervous system primarily by the -best-synchronized or modal portion of the action potential response.