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Effect of current stimulus on in vivo cochlear mechanics
Anand A Parthasarathi1, Karl Grosh, Jiefu Zheng
1Department of Biomedical Engineering, 3304 G. G. Brown, University of Michigan, Ann Arbor, Michigan 48109, USA.
The Journal of the Acoustical Society of America
|February 1, 2003
Summary
Direct current stimulation alters the basilar membrane's acoustic response. Positive current enhances gain and best frequency, while negative current has the opposite effect, impacting cochlear microphonics and harmonic levels.
Area of Science:
- Auditory Neuroscience
- Bioacoustics
- Biophysics
Background:
- The basilar membrane (BM) is crucial for auditory frequency analysis.
- Understanding how electrical stimulation affects BM mechanics is vital for hearing research.
Purpose of the Study:
- To investigate the influence of direct current (DC) stimulation on the acoustic impulse response of the basilar membrane.
- To elucidate the effects of DC polarity on BM gain, best frequency, and harmonic content.
Main Methods:
- Experimental study of the basilar membrane's acoustic impulse response under DC stimulation.
- Utilizing a computational model of outer hair cell (OHC) activity to interpret experimental findings.
Main Results:
- Positive DC current in scala vestibuli enhances BM gain and best frequency; negative current reverses this effect.
- DC stimulation alters low-frequency cochlear microphonic amplitude and changes the relative levels of BM vibration harmonics.
- OHC models demonstrate hyperpolarization-induced shortening under tension due to voltage-dependent stiffness.
Conclusions:
- DC stimulation significantly modulates the mechanical and electrical properties of the basilar membrane.
- OHC electromechanical coupling is a key factor in DC-induced changes in BM response.
- Findings highlight the importance of in vivo electrical and mechanical loading conditions in auditory function.