High-frequency sensitivity of the mature gerbil cochlea and its development

Edward H. Overstreet, Claus Peter Richter, Andrei N. Temchin, Mary Ann Cheatham, Mario A. Ruggero*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

The thresholds of compound action potentials evoked by tone pips were measured in the cochleae of anesthetized gerbils, both in adults and in neonates aged 14, 16, 18, 20 and 30 days, using round-window electrodes. Stapes vibrations were also measured, using a laser velocimeter, in many of the same ears of adults and neonates aged 14, 16, 18 and 20 days to assess cochlear sensitivity in isolation from middle ear effects and to circumvent problems associated with calibration of acoustic stimuli at high frequencies. Whether referenced to sound pressure level in the ear canal or stapes vibration velocity, thresholds in adults were roughly uniform in the entire range of tested frequencies, 1.25-38.5 kHz. In neonates, thresholds decreased systematically as a function of age, with the largest reductions occurring at the highest frequencies. Thresholds remained slightly immature at all frequencies 30 days after birth. The results for adult gerbils are consistent with the recent finding that basilar-membrane responses to characteristic frequency tones normalized to stapes vibrations are as sensitive at sites near the round window as at more apical sites. The results for neonates confirm that the extreme basal region of the cochlea is the last to approach maturity, with substantial development occurring between 20 and 30 days after birth.

Original languageEnglish (US)
Pages (from-to)19-27
Number of pages9
JournalAudiology and Neuro-Otology
Volume8
Issue number1
DOIs
StatePublished - 2003

Keywords

  • Basilar membrane
  • Cochlea
  • Development
  • Gerbil
  • Middle ear
  • Stapes

ASJC Scopus subject areas

  • Physiology
  • Otorhinolaryngology
  • Sensory Systems
  • Speech and Hearing

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