This proposal includes three new projects addressing the mechanical """"""""cochlear amplifiers"""""""" of the inner ears of vertebrates. The first project investigates the effects of various noxious agents on the responses to sound of the basilar membrane, the outer hair cells and auditory-nerve fibers at basal sites of the chinchilla cochlea. These agents have been chosen because they target the somatic electromotility of outer hair ceils (the putative amplifiers of mammalian cochleae) in vitro, affect otoacoustic emissions and/or otherwise affect outer hair cell function in-vivo or in-vitro. The second project will extend our recent findings on the development of passive cochlear traveling waves in newborn Mongolian gerbils by studying the maturation of the cochlear amplifier as reflected in the growth of basilar-membrane sensitivity and the strength of compressive nonlinearities. The third project consists of mechanical and electrophysiological recordings in the basilar papillae (analogues of the mammalian cochlea) of avian and reptilian species (pigeon, alligator and turtle), which have basilar membranes but not outer hair cells. The goal is to ascertain whether basilar-membrane vibrations in these species reflect the presence of stereociliar cochlear amplifiers which may play a role equivalent to that of outer hair cell somatic electromotility in mammalian cochleae. The results of the proposed research should be of fundamental value in defining the mechanical bases of auditory transduction in the inner ears of mammals and other vertebrates and may also serve to clarify the pathophysiology of sensorineural hearing loss in humans.

National Institute of Health (NIH)
National Institute on Deafness and Other Communication Disorders (NIDCD)
Research Project (R01)
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Special Emphasis Panel (ZRG1-IFCN-6 (01))
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Donahue, Amy
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Northwestern University at Chicago
Other Health Professions
Schools of Arts and Sciences
United States
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Charaziak, Karolina K; Siegel, Jonathan H; Shera, Christopher A (2018) Spectral Ripples in Round-Window Cochlear Microphonics: Evidence for Multiple Generation Mechanisms. J Assoc Res Otolaryngol 19:401-419
Temchin, Andrei N; Ruggero, Mario A (2014) Spatial irregularities of sensitivity along the organ of Corti of the cochlea. J Neurosci 34:11349-54
Recio-Spinoso, Alberto; Fan, Yun-Hui; Ruggero, Mario A (2011) Basilar-membrane responses to broadband noise modeled using linear filters with rational transfer functions. IEEE Trans Biomed Eng 58:1456-65
Temchin, Andrei N; Recio-Spinoso, Alberto; Ruggero, Mario A (2011) Timing of cochlear responses inferred from frequency-threshold tuning curves of auditory-nerve fibers. Hear Res 272:178-86
Temchin, Andrei N; Ruggero, Mario A (2010) Phase-locked responses to tones of chinchilla auditory nerve fibers: implications for apical cochlear mechanics. J Assoc Res Otolaryngol 11:297-318
Recio-Spinoso, Alberto; Narayan, Shyamla S; Ruggero, Mario A (2009) Basilar membrane responses to noise at a basal site of the chinchilla cochlea: quasi-linear filtering. J Assoc Res Otolaryngol 10:471-84
Ruggero, Mario A; Temchin, Andrei N (2007) Similarity of traveling-wave delays in the hearing organs of humans and other tetrapods. J Assoc Res Otolaryngol 8:153-66
Temchin, Andrei N; Recio-Spinoso, Alberto; van Dijk, Pim et al. (2005) Wiener kernels of chinchilla auditory-nerve fibers: verification using responses to tones, clicks, and noise and comparison with basilar-membrane vibrations. J Neurophysiol 93:3635-48
Siegel, Jonathan H; Cerka, Amanda J; Recio-Spinoso, Alberto et al. (2005) Delays of stimulus-frequency otoacoustic emissions and cochlear vibrations contradict the theory of coherent reflection filtering. J Acoust Soc Am 118:2434-43
Ruggero, Mario A; Temchin, Andrei N (2005) Unexceptional sharpness of frequency tuning in the human cochlea. Proc Natl Acad Sci U S A 102:18614-9

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