title: Application of frequency modulated chirp stimuli for rapid and sensitive ABR measurements in the rat.
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.
authors.affiliation: Department of Hearing and Speech Sciences, Vanderbilt Bill Wilkerson Center for Otolaryngology and Communication Sciences, Vanderbilt University Medical Center, Nashville, TN 37232-8548, United States.
authors.forename: Christopher
authors.initials: C
authors.lastname: Spankovich
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Hood
authors.forename: D
authors.initials: D
authors.lastname: Wesley Grantham
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Polley
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods* / Q000706:statistics & numerical data; D000818:Animals; D001309:Auditory Threshold / Q000502:physiology*; D001489:Basilar Membrane / Q000502:physiology; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D051381:Rats; D012680:Sensitivity and Specificity