To establish the magnitude of the electromechanical force generated by the outer hair cell from the mammalian cochlea, we used a cylindrical membrane model characterized by area and shear moduli for a passive elastic element, and a membrane potential-dependent, active tension-generating element. We measured pressure-strain relations to determine the elastic moduli, and found the area modulus was both close to a lipid bilayer and an order of magnitude larger than the shear modulus. We also determined that the active tension element is nearly isotropic, with an amplitude sensitivity of about 2x10~2 Nm-1V-1. At 73 dB of acoustical stimulation, the active force generated per outer hair cell is about 0.6 nN--close to the force applied to a corresponding area of the basilar membrane by acoustic pressure. This finding supports the hypothesis that the outer hair cell acts as a feedback motor in the fine-tuning mechanism of the mammalian ear. A model has been developed to study outer hair-cell feedback in waves on the cochlear partitions and the resulting sharpening mechanism.

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Intramural Research (Z01)
Project #
1Z01RR010407-05
Application #
2590331
Study Section
Special Emphasis Panel (BEI)
Project Start
Project End
Budget Start
Budget End
Support Year
5
Fiscal Year
1996
Total Cost
Indirect Cost
Name
National Center for Research Resources
Department
Type
DUNS #
City
State
Country
United States
Zip Code