""""""""Peripheral Mechanisms of Deafness"""""""" proposes to test the hypothesis that normal cochlear mechanics are dependent on active (energy- consuming) processes which functionally feed back onto the vibration of the basilar membrane. Specifically, this project will attempt to establish whether the outer hair cell of the mammalian inner ear participate in determining the properties of the basilar membrane, thus also largely determining the response properties of the cochlear primary afferents. Two parallel strategies, both based on the disruption of the normal function of the organ of Corti, will be used. The first strategy consists of measuring the acoustically-evoked vibrations of the basilar membrane before, during and after transient (reversible) alterations or dysfunction of the outer hair cells, induced by procedures such as stimulation of the olivocochlear efferent system, injection of diuretics or instillation of cyanide into the perilymphatic spaces. The second strategy consists of studying the activity of individual cochlear afferents in animals whose cochleas have been permanently damaged by chronic administration of ototoxic agents. Both sets of measurements, mechanical on the basilar membrane and microelectrode recordings from cochlear afferents, will be performed in a single species, the chinchilla. The basilar membrane vibration will be measured by means of an application of the Mossbauer effect that permits detection of very low velocities (e.g., 0.03 mm/sec). Results of the proposed investigation will be of value in defining the bidirectional relationship between the sensory hair cells and the basilar membrane in normal mammalian cochleas and will also serve to clarify the pathophysiology of sensorineural hearing loss in humans.

Project Start
1997-07-01
Project End
1999-06-30
Budget Start
1996-10-01
Budget End
1997-09-30
Support Year
23
Fiscal Year
1997
Total Cost
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Type
DUNS #
168559177
City
Minneapolis
State
MN
Country
United States
Zip Code
55455
Donaldson, Gail S; Kreft, Heather A; Litvak, Leonid (2005) Place-pitch discrimination of single- versus dual-electrode stimuli by cochlear implant users (L). J Acoust Soc Am 118:623-6
Munson, Benjamin; Nelson, Peggy B (2005) Phonetic identification in quiet and in noise by listeners with cochlear implants. J Acoust Soc Am 118:2607-17
Collison, Elizabeth A; Munson, Benjamin; Carney, Arlene Earley (2004) Relations among linguistic and cognitive skills and spoken word recognition in adults with cochlear implants. J Speech Lang Hear Res 47:496-508
Munson, Benjamin; Donaldson, Gail S; Allen, Shanna L et al. (2003) Patterns of phoneme perception errors by listeners with cochlear implants as a function of overall speech perception ability. J Acoust Soc Am 113:925-35
Robles, L; Ruggero, M A (2001) Mechanics of the mammalian cochlea. Physiol Rev 81:1305-52
Javel, E; Viemeister, N F (2000) Stochastic properties of cat auditory nerve responses to electric and acoustic stimuli and application to intensity discrimination. J Acoust Soc Am 107:908-21
Recio, A; Rich, N C; Narayan, S S et al. (1998) Basilar-membrane responses to clicks at the base of the chinchilla cochlea. J Acoust Soc Am 103:1972-89
Robles, L; Ruggero, M A; Rich, N C (1997) Two-tone distortion on the basilar membrane of the chinchilla cochlea. J Neurophysiol 77:2385-99
Temchin, A N; Rich, N C; Ruggero, M A (1997) Low-frequency suppression of auditory nerve responses to characteristic frequency tones. Hear Res 113:29-56
Ruggero, M A; Rich, N C; Recio, A et al. (1997) Basilar-membrane responses to tones at the base of the chinchilla cochlea. J Acoust Soc Am 101:2151-63