An analytic approach to identifying the sources of the low-frequency round window cochlear response

• Published in: Hearing research 2019-04, Vol.375, p.53-65
• Main Authors: Kamerer, Aryn M., Chertoff, Mark E.
• Format: Article
• Language: English
• Subjects: Acoustic Stimulation - methods; Animals; Cochlear Microphonic Potentials - physiology; Cochlear Nerve - physiology; Gerbillinae; Hair Cells, Auditory, Inner - physiology; Hair Cells, Auditory, Outer - physiology; Models, Animal; Models, Neurological; Nonlinear Dynamics; Round Window, Ear - physiology
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/j.heares.2019.02.001

The cochlear microphonic, traditionally thought of as an indication of electrical current flow through hair cells, in conjunction with suppressing high-pass noise or tones, is a promising method of assessing the health of outer hair cells at specific locations along the cochlear partition. We propose that the electrical potential recorded from the round window in gerbils in response to low-frequency tones, which we call cochlear response (CR), contains significant responses from multiple cellular sources, which may expand its diagnostic purview. In this study, CR is measured in the gerbil and modeled to identify its contributing sources. CR was recorded via an electrode placed in the round window niche of sixteen Mongolian gerbils and elicited with a 45 Hz tone burst embedded in 18 high-pass filtered noise conditions to target responses from increasing regions along the cochlear partition. Possible sources were modeled using previously-published hair cell and auditory nerve response data, and then weighted and combined using linear regression to produce a model response that fits closely to the mean CR waveform. The significant contributing sources identified by the model are outer hair cells, inner hair cells, and the auditory nerve. We conclude that the low-frequency CR contains contributions from several cellular sources. •Distortions in the 45 Hz cochlear response are products of nonlinear mechanisms in the gerbil cochlea.•Inner and outer hair cells and apical auditory nerve significantly contribute to a model of the 45 Hz cochlear response.•The low-frequency cochlear response may be useful to both physiological hearing research and clinical audiology.