Action potentials in the cat at low sound intensities: thresholds, latencies, and rates of change.
The interpretation of whole-nerve action potentials is a topic of increasing importance in both clinical and research settings. This effort has been hampered by a lack of data on the action potential that are theoretically interpretable and systematically measured over a wide range of frequencies and at low sound intensities. Therefore, the present study was designed to measure the thresholds, latencies, and rates of change in the whole-nerve action potential in response to constant-spectral-width tone pips at eight frequencies between 0.5 and 20 kHz in the cat ear. These quantities were calculated by a linear regression technique from round-window potentials in 28 normal ears. They were found to be consistently within approximately 18 dB of previously published behavioral measures, a difference attributable to temporal integration. The interanimal variability had a standard deviation of about 5 dB and the intra-animal variability was extremely low. The growth of amplitude across frequencies, the rate of change of latency with intensity changes, and the latency at threshold all demonstrated orderly relationships which are presented. The data were all consistent with contention that the potentials were being produced by a single population of cells located at a place consistent with the frequency of the eliciting tone. The methods used provide exceedingly stable measures and should be applicable in both clinical and research settings.
D000161:Acoustic Stimulation; D000200:Action Potentials; D000818:Animals; D001309:Auditory Threshold / Q000502:physiology*; D002415:Cats; D000159:Vestibulocochlear Nerve / Q000502:physiology*