The Development of a Single Frequency Place in the Mammalian Cochlea: The Cochlear Resonance in the Mustached Bat Pteronotus parnellii

Ian J. Russell, Markus Drexl, Elisabeth Foeller, Marianne Vater, Manfred Kössll

Research output: Contribution to journalArticlepeer-review

Abstract

Cochlear microphonic potentials (CMs) were recorded from the sharply tuned, strongly resonant auditory foveae of 1- to 5-week-old mustached bats that were anesthetized with Rompun and Ketavet. The fovea processes Doppler-shifted echo responses of the constant-frequency component of echolocation calls. During development, the frequency and tuning sharpness of the cochlear resonance increases, and CM ringing persists for longer after the tone. CM is relatively insensitive at tone onset and grows linearly with increased stimulus level. During the tone, the CM is more sensitive and grows compressively with increased stimulus level and phase leads onset CM by 90° for frequencies below the resonance. CM during the ringing is also sensitive and compressive and phase leads onset CM by 180° below the resonance and lags it by 180° above the resonance. Throughout postnatal development, CMs measured during the tone and in the ringing increase both in sensitivity and compression. The cochlear resonance appears to be attributable to interaction between two oscillators. The more broadly tuned oscillator dominates the onset response, and the narrowly tuned oscillator dominates the ringing. Early in development, mechanical coupling between the oscillators results in a relatively broadly tuned system with several frequency modes in the CM at tone onset and in the CM ringing. Beating occurs between the resonance and the stimulus response during the tone and between two components of the narrowly tuned oscillator at tone offset. At maturity, the CM has three modes for frequencies within 10 kHz of the resonance at tone onset and a single, sharply tuned mode in the ringing.

Original languageEnglish
Pages (from-to)10971-10981
Number of pages11
JournalJournal of Neuroscience
Volume23
Issue number34
Publication statusPublished - 26 Nov 2003

Keywords

  • Auditory fovea
  • Basilar membrane
  • Cochlea
  • Cochlear amplifier
  • Frequency tuning
  • Microphonic potential
  • Mustached bat
  • Resonance
  • Synchronization
  • Tectorial membrane

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