title: Mapping auditory nerve firing density using high-level compound action potentials and high-pass noise masking.
abstract: Future implementation of regenerative treatments for sensorineural hearing loss may be hindered by the lack of diagnostic tools that specify the target(s) within the cochlea and auditory nerve for delivery of therapeutic agents. Recent research has indicated that the amplitude of high-level compound action potentials (CAPs) is a good predictor of overall auditory nerve survival, but does not pinpoint the location of neural damage. A location-specific estimate of nerve pathology may be possible by using a masking paradigm and high-level CAPs to map auditory nerve firing density throughout the cochlea. This initial study in gerbil utilized a high-pass masking paradigm to determine normative ranges for CAP-derived neural firing density functions using broadband chirp stimuli and low-frequency tonebursts, and to determine if cochlear outer hair cell (OHC) pathology alters the distribution of neural firing in the cochlea. Neural firing distributions for moderate-intensity (60 dB pSPL) chirps were affected by OHC pathology whereas those derived with high-level (90 dB pSPL) chirps were not. These results suggest that CAP-derived neural firing distributions for high-level chirps may provide an estimate of auditory nerve survival that is independent of OHC pathology.
authors.affiliation: Department of Hearing and Speech, University of Kansas Medical Center, 3031 Miller, 3901 Rainbow Boulevard, Kansas City, Kansas 66160-7605, USA. bearl@kumc.edu
authors.forename: Brian R
authors.initials: BR
authors.lastname: Earl
authors.forename: Mark E
authors.initials: ME
authors.lastname: Chertoff
mesh_terms: D000161:Acoustic Stimulation; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001309:Auditory Threshold; D002491:Central Nervous System Agents / Q000494:pharmacology; D015834:Cochlear Diseases / Q000503:physiopathology; D003056:Cochlear Nerve / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005839:Gentamicins / Q000494:pharmacology; D005849:Gerbillinae; D006198:Hair Cells, Auditory / Q000502:physiology; D006319:Hearing Loss, Sensorineural / Q000503:physiopathology; D009431:Neural Conduction / Q000502:physiology; D009622:Noise; D010470:Perceptual Masking / Q000502:physiology*; D011930:Reaction Time
chemical_list: D002491:Central Nervous System Agents; D005839:Gentamicins