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BioMed Research International
Volume 2015, Article ID 727434, 12 pages
http://dx.doi.org/10.1155/2015/727434
Research Article

All Three Rows of Outer Hair Cells Are Required for Cochlear Amplification

1Department of Mechanical Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065, Japan
2PRESTO, JST, 4-1-8 Honcho, Kawaguchi 332-0012, Japan
3Department of Bioengineering and Robotics, Tohoku University, 6-6-01 Aoba-yama, Sendai 980-8579, Japan
4Department of Intelligent Information Systems, Faculty of Science and Technology, Tohoku Bunka Gakuen University, 6-45-1 Kunimi, Sendai 981-8551, Japan

Received 26 March 2015; Accepted 28 June 2015

Academic Editor: Paul C. Dechow

Copyright © 2015 Michio Murakoshi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In the mammalian auditory system, the three rows of outer hair cells (OHCs) located in the cochlea are thought to increase the displacement amplitude of the organ of Corti. This cochlear amplification is thought to contribute to the high sensitivity, wide dynamic range, and sharp frequency selectivity of the hearing system. Recent studies have shown that traumatic stimuli, such as noise exposure and ototoxic acid, cause functional loss of OHCs in one, two, or all three rows. However, the degree of decrease in cochlear amplification caused by such functional losses remains unclear. In the present study, a finite element model of a cross section of the gerbil cochlea was constructed. Then, to determine effects of the functional losses of OHCs on the cochlear amplification, changes in the displacement amplitude of the basilar membrane (BM) due to the functional losses of OHCs were calculated. Results showed that the displacement amplitude of the BM decreases significantly when a single row of OHCs lost its function, suggesting that all three rows of OHCs are required for cochlear amplification.