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In vivo outer hair cell length changes expose the active process in the cochlea
Dingjun Zha1, Fangyi Chen, Sripriya Ramamoorthy
1Oregon Hearing Research Center, Oregon Health and Science University, Portland, Oregon, United States of America.
Plos One
|April 13, 2012
Summary
Outer hair cells dynamically change length in the cochlea to amplify sound. These in vivo length changes, measured for the first time, depend on sound level, validating the active hearing process.
Area of Science:
- Auditory Neuroscience
- Bioacoustics
- Cellular Mechanics
Background:
- Mammalian hearing relies on the cochlea amplifying sound-evoked vibrations.
- Outer hair cells (OHCs) generate forces via protein motors for amplification.
- OHCs must dynamically change length, timed with stimuli, to transmit power.
Purpose of the Study:
- To measure outer hair cell length changes in vivo.
- To investigate the timing and magnitude of OHC length changes.
- To validate the role of OHC active processes in hearing.
Main Methods:
- In vivo optical coherence tomography (OCT) was employed.
- Measurements were conducted in living guinea pigs.
- Outer hair cell length changes were analyzed under varying stimulus levels.
Main Results:
- Outer hair cells exhibit length changes in vivo.
- The timing and magnitude of these length changes are stimulus-level dependent.
- Unexpected dynamics in OHC length changes were observed.
Conclusions:
- Measured level-dependent length changes are crucial for validating OHC power output.
- This study provides direct evidence for the active process underlying normal hearing.
- Findings offer insights into cochlear mechanics and auditory amplification.
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