Outer hair cell somatic, not hair bundle, motility is the basis of the cochlear amplifier

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Abstract

Sensitivity, dynamic range and frequency tuning of the cochlea are attributed to amplification involving outer hair cell stereocilia and/or somatic motility. We measured acoustically and electrically elicited basilar membrane displacements from the cochleae of wild-type and TectaΔENT/ΔENT mice, in which stereocilia are unable to contribute to amplification near threshold. Electrically elicited responses from TectaΔENT/ΔENT mice were markedly similar to acoustically and electrically elicited responses from wild-type mice. We conclude that somatic, and not stereocilia, motility is the basis of cochlear amplification.

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Figure 1: Basilar membrane responses to acoustic stimulation of the mouse cochlea.
Figure 2: Basilar membrane responses to electrical stimulation of the mouse cochlea.

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Acknowledgements

We thank G. Richardson for making the Tecta mice available. We thank J. Hartley for technical assistance and C. Kros for helpful comments on the manuscript. This work was supported by the Medical Research Council. M.M.M.L. was supported by a Federation of European Neuroscientists—International Brain Research Organization Fellowship, and M.D. was supported by a Deutsche Forschungsgemeinschaft Fellowship.

Author information

M.M.M.L. and M.D. contributed equally to measuring and analyzing the responses to acoustical and electrical stimulation of the cochlea. V.A.L. measured and analyzed responses to acoustical stimulation. A.N.L. contributed to the experimental design, directed the research and wrote the software. I.J.R. designed the experiments and contributed largely to data analysis and writing the paper.

Correspondence to Ian J Russell.

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Mellado Lagarde, M., Drexl, M., Lukashkina, V. et al. Outer hair cell somatic, not hair bundle, motility is the basis of the cochlear amplifier. Nat Neurosci 11, 746–748 (2008) doi:10.1038/nn.2129

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