Responses of peripheral auditory neurons to two-tone stimuli during development: III. Rate facilitation.
Approximately 25% of peripheral auditory neurons having low characteristic frequencies (CFs) and broad tuning, and recorded from immature animals, responded to two-tone stimuli with increases in discharge rate greater than predicted by linear summation of the responses to probe tones (facilitation), in contrast to the two-tone suppression observed in adult animals and in more sharply tuned immature neurons. Facilitation was not seen after 81 gestational days and was not observed when test tones produced a substantial increase in rate when presented alone. The fact that some neural responses were facilitated under conditions of two-tone stimulation during the final stages of cochlear differentiation provides additional evidence that signal transduction is fundamentally different in neonatal kittens than in adults. A linear model of basilar membrane mechanics coupled to nonlinear neural processes is proposed which can account for the production of facilitation.
Fitzakerley
J L
JL
Department of Physiology, Creighton University, Boys Town National Research Hospital, Omaha, NE 68131.
McGee
J A
JA
Walsh
E J
EJ
D000161:Acoustic Stimulation; D000818:Animals; D000831:Animals, Newborn; D001309:Auditory Threshold / Q000502:physiology; D002415:Cats; D017626:Cochlear Nucleus / Q000254:growth & development / Q000502:physiology; D005072:Evoked Potentials, Auditory; D009474:Neurons / Q000502:physiology; D000159:Vestibulocochlear Nerve / Q000254:growth & development / Q000502:physiology*