Application of frequency modulated chirp stimuli for rapid and sensitive ABR measurements in the rat

Hear Res. 2008 Nov;245(1-2):92-7. doi: 10.1016/j.heares.2008.09.001. Epub 2008 Sep 10.

Abstract

Rodents have proven to be a useful model system to screen genes, ototoxic compounds and sound exposure protocols that may play a role in hearing loss. High-throughput screening depends upon a rapid and reliable functional assay for hearing loss. This study describes the use of a frequency modulated (FM) chirp stimulus as an alternative to the click to derive a rapid assessment of auditory brainstem response (ABR) threshold in the rodent. We designed a rising frequency A-chirp based upon the spatial mapping of preferred frequency along the rat basilar membrane to provide a more synchronous and equipotent input across the length of the cochlea. We observed that the ABR wave I and wave IV amplitudes evoked by the A-chirp were significantly greater than the click and that A-chirp minimum response thresholds were lower than the click. Subsequent analyses compared the efficacy of the A-chirp to linear, time-reversed and amplitude-reversed chirps and confirmed that the A-chirp was most effective chirp configuration. These data suggest that the A-chirp may be optimally suited as a single screening broad-frequency stimulus for rapid ABR threshold estimations in the rodent and could serve to complement more detailed frequency-specific physiologic and behavioral estimates of hearing threshold.

MeSH terms

  • Acoustic Stimulation / methods*
  • Acoustic Stimulation / statistics & numerical data
  • Animals
  • Auditory Threshold / physiology*
  • Basilar Membrane / physiology
  • Evoked Potentials, Auditory, Brain Stem / physiology*
  • Rats
  • Sensitivity and Specificity