The goals of this project are to characterize and use a new animal model for the measurement of outer hair cell (OHC) motility in vivo. The electrical stimulation of the cochlea with constant current acoustic frequency sinusoids results in electrically-evoked otoacoustic emissions (EEOAE) that can be measured in the ear canal. Placement of an electrode on the round window membrane of the cochlea generates the EEOAE and is non invasive to the inner ear. There are three Specific Aims.
In Aim 1, the relationship of the parameters of the stimulation, particularly the position of the stimulation electrodes, to the EEOAE that is produced will first be determined. The goal is to show that the measured EEOAE bears a quantitative relationship to a particular population of OHCs. We will also determine the EEOAE produced from current injected into scala media, in order to relate the data of the new extracochlear stimulation method to the published literature where intracochlear current delivery has been used. In further experiments, this goal will also be achieved by altering and eliminating a population of hair cells with ototoxic drugs. A morphological assessment of the toxic effects of the drug treatment on OHCs will be performed. We will coordinate these studies with those of Project 2 (Aim 1) where the psychophysical percept of electrical stimulation is determined.
In Aim 2, the goal is to determine whether the linearity of the EEOAE bears a predictable relationship to the known properties of electromotility obtained from in vitro studies. The quality and significance of in vivo electromotility is not known and thus this study should determine how electromotility contributes to cochlear nonlinear responses. This study is coordinated with Project 3 (Aim 3) where the influence of efferent neural activation on the EEOAE is explored. The measurement of the EEOAE not only provides information about the basic properties of electromotility in vivo but could also serve as the basis of a human hearing test determining the presence and health status of cochlear OHCs in future work.

Project Start
1999-12-01
Project End
2000-11-30
Budget Start
1998-10-01
Budget End
1999-09-30
Support Year
34
Fiscal Year
2000
Total Cost
$315,282
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Type
DUNS #
791277940
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Stefanescu, Roxana A; Koehler, Seth D; Shore, Susan E (2015) Stimulus-timing-dependent modifications of rate-level functions in animals with and without tinnitus. J Neurophysiol 113:956-70
Basura, Gregory J; Koehler, Seth D; Shore, Susan E (2015) Bimodal stimulus timing-dependent plasticity in primary auditory cortex is altered after noise exposure with and without tinnitus. J Neurophysiol 114:3064-75
Le Prell, Colleen G; Hughes, Larry F; Bledsoe Jr, Sanford C (2014) Dynorphin release by the lateral olivocochlear efferents may inhibit auditory nerve activity: a cochlear drug delivery study. Neurosci Lett 571:17-22
Le Prell, Colleen G; Dolan, David F; Hughes, Larry F et al. (2014) Disruption of lateral olivocochlear neurons with a dopaminergic neurotoxin depresses spontaneous auditory nerve activity. Neurosci Lett 582:54-8
Koehler, Seth D; Shore, Susan E (2013) Stimulus-timing dependent multisensory plasticity in the guinea pig dorsal cochlear nucleus. PLoS One 8:e59828
Basura, Gregory J; Koehler, Seth D; Shore, Susan E (2012) Multi-sensory integration in brainstem and auditory cortex. Brain Res 1485:95-107
Dehmel, Susanne; Pradhan, Shashwati; Koehler, Seth et al. (2012) Noise overexposure alters long-term somatosensory-auditory processing in the dorsal cochlear nucleus--possible basis for tinnitus-related hyperactivity? J Neurosci 32:1660-71
Koehler, Seth D; Pradhan, Shashwati; Manis, Paul B et al. (2011) Somatosensory inputs modify auditory spike timing in dorsal cochlear nucleus principal cells. Eur J Neurosci 33:409-20
Bledsoe Jr, Sanford C; Koehler, Seth; Tucci, Debara L et al. (2009) Ventral cochlear nucleus responses to contralateral sound are mediated by commissural and olivocochlear pathways. J Neurophysiol 102:886-900
Skjonsberg, Asa; Halsey, Karin; Ulfendahl, Mats et al. (2007) Exploring efferent-mediated DPOAE adaptation in three different guinea pig strains. Hear Res 224:27-33

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