Fluid flow stimulates the hair bundles (HB) of the inner hair cells (IHC) of the cochlea opening the mechano-electric transducer (MET) channels of the IHCs. The resulting current depolarizes the cell body inducing neurotransmitter release and, ultimately, auditory nerve stimulation. The active machinery of the cochlea, driven by motility of outer hair cells (OHC), both tunes the microfluidic excitation of the IHC HBs and provides for nonlinear compression. However, the relative influence of OHC somatic and HB motility on this final fluidic forcing in the cochlea has yet to be conclusively apportioned nor has the microfluidi flow that excites the IHC HB.
The specific aims of this grant are to develop models of IHC HB stimulation by developing a microfluidic representation of the flow in the subtectorial space and coupling these models to the macroscopic model of the cochlea.
In specific aim 2 we seek to determine the tonotopic dependence and combined effect of active OHC forces on the organ of Corti and of the fluidic forces on the IHC HB. The overarching goal of this research is to develop a complete fluid-mechanical-electrical model that describes the response of the cochlea to both external acoustic and internal electrical stimulation. If successful, this model will enhance our understanding of failure mechanisms in the cochlea, answering important questions as to the morphological elements of the cochlea that fail and why. This will improve noninvasive diagnosis of hearing as abnormalities in the response measures can be linked to specific pathologies. Further, as our model can predict the interaction of electrical and acoustic stimulus it will enable a prediction of the effect of a combined acoustic-electric prosthesis (such as would be used in schemes where some residual hearing is still present). Finally, a mathematical model of the cochlear response to sound over the entire spectrum will help us to understand how important classes of signals are processed in the cochlea (such as speech and music) which can lead to better speech processing algorithms or cochlear implant electrical stimulation paradigms.

Public Health Relevance

We seek to understand the active processes that are responsible for normal hearing by building mathematical models simulating the behavior of the cochlea, the transducer of the hearing system. By understanding the cochlea well enough to model it, we hope to predict how the cochlea might fail, say in response to loud sound or age, and guide the development of protective approaches or enhanced prosthetics. In addition, a predictive mathematical model will enable the development of new noninvasive tests to better interrogate the health of one's hearing.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC004084-12
Application #
8489275
Study Section
Auditory System Study Section (AUD)
Program Officer
Cyr, Janet
Project Start
1999-05-01
Project End
2017-05-31
Budget Start
2013-06-01
Budget End
2014-05-31
Support Year
12
Fiscal Year
2013
Total Cost
$231,518
Indirect Cost
$70,018
Name
University of Michigan Ann Arbor
Department
None
Type
Schools of Engineering
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Ren, Tianying; He, Wenxuan; Li, Yizeng et al. (2014) Light-induced vibration in the hearing organ. Sci Rep 4:5941
Cheng, Lei; Li, Yizeng; Grosh, Karl (2013) Including fluid shear viscosity in a structural acoustic finite element model using a scalar fluid representation. J Comput Phys 247:248-261
Meaud, Julien; Grosh, Karl (2009) Predicting the role of OHC somatic motility and HB motility in cochlear amplification using a mathematical model. Hear Res :
He, Wenxuan; Fridberger, Anders; Porsov, Edward et al. (2008) Reverse wave propagation in the cochlea. Proc Natl Acad Sci U S A 105:2729-33
Cheng, Lei; White, Robert D; Grosh, Karl (2008) Three Dimensional Viscous Finite Element Formulation For Acoustic Fluid Structure Interaction. Comput Methods Appl Mech Eng 197:4160-4172
Zheng, Jiefu; Deo, Niranjan; Zou, Yuan et al. (2007) Chlorpromazine alters cochlear mechanics and amplification: in vivo evidence for a role of stiffness modulation in the organ of corti. J Neurophysiol 97:994-1004
Ramamoorthy, Sripriya; Deo, Niranjan V; Grosh, Karl (2007) A mechano-electro-acoustical model for the cochlea: response to acoustic stimuli. J Acoust Soc Am 121:2758-73
Spector, A A; Deo, N; Grosh, K et al. (2006) Electromechanical models of the outer hair cell composite membrane. J Membr Biol 209:135-52
Deo, Niranjan; Grosh, Karl (2005) Plified nonlinear outer hair cell models. J Acoust Soc Am 117:2141-6
Halsey, Kirin; Fegelman, Karen; Raphael, Yehoash et al. (2005) Long-term effects of acoustic trauma on electrically evoked otoacoustic emission. J Assoc Res Otolaryngol 6:324-40

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