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Force generation by mammalian hair bundles supports a role in cochlear amplification


It is generally accepted that the acute sensitivity and frequency discrimination of mammalian hearing requires active mechanical amplification of the sound stimulus within the cochlea1. The prevailing hypothesis is that this amplification stems from somatic electromotility of the outer hair cells attributable to the motor protein prestin2,3. Thus outer hair cells contract and elongate in synchrony with the sound-evoked receptor potential4,5. But problems arise with this mechanism at high frequencies, where the periodic component of the receptor potential will be attenuated by the membrane time constant. On the basis of work in non-mammalian vertebrates, force generation by the hair bundles has been proposed as an alternative means of boosting the mechanical stimulus6,7. Here we show that hair bundles of mammalian outer hair cells can also produce force on a submillisecond timescale linked to adaptation of the mechanotransducer channels. Because the bundle motor may ultimately be limited by the deactivation rate of the channels, it could theoretically operate at high frequencies. Our results show the existence of another force generator in outer hair cells that may participate in cochlear amplification.

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Figure 1: Method of hair bundle stimulation.
Figure 2: Mechanical properties of the OHC hair bundle.
Figure 3: Force generation by the OHC bundle.
Figure 4: Effects of Ca2+ on OHC bundle mechanics.


  1. Dallos, P. The active cochlea. J. Neurosci. 12, 4575–4585 (1992)

    CAS  Article  Google Scholar 

  2. Zheng, J. et al. Prestin is the motor protein of cochlear outer hair cells. Nature 405, 149–155 (2000)

    ADS  CAS  Article  Google Scholar 

  3. Liberman, M. C. et al. Prestin is required for electromotility of the outer hair cell and for the cochlear amplifier. Nature 419, 300–304 (2002)

    ADS  CAS  Article  Google Scholar 

  4. Brownell, W. E., Bader, C. R., Bertrand, D. & de Ribaupierre, Y. Evoked mechanical responses of isolated cochlear outer hair cells. Science 227, 194–196 (1985)

    ADS  CAS  Article  Google Scholar 

  5. Ashmore, J. F. A fast motile response in guinea-pig outer hair cells: the cellular basis of the cochlear amplifier. J. Physiol. (Lond.) 388, 323–347 (1987)

    CAS  Article  Google Scholar 

  6. Hudspeth, A. J. Mechanical amplification of stimuli by hair cells. Curr. Opin. Neurobiol. 7, 480–486 (1997)

    CAS  Article  Google Scholar 

  7. Fettiplace, R., Ricci, A. J. & Hackney, C. M. Clues to the cochlear amplifier from the turtle ear. Trends Neurosci. 24, 169–175 (2001)

    CAS  Article  Google Scholar 

  8. Hudspeth, A. J. How the ear's works work. Nature 341, 397–404 (1989)

    ADS  CAS  Article  Google Scholar 

  9. Kros, C. J., Rüsch, A. & Richardson, G. P. Mechano-electrical transducer currents in hair cells of the cultured neonatal mouse cochlea. Proc. R. Soc. Lond. B 249, 185–193 (1992)

    ADS  CAS  Article  Google Scholar 

  10. Kennedy, H. J., Evans, M. G., Crawford, A. C. & Fettiplace, R. Fast adaptation of mechanoelectrical transducer channels in mammalian cochlear hair cells. Nature Neurosci. 6, 832–836 (2003)

    CAS  Article  Google Scholar 

  11. He, D. Z. Z., Jia, S. & Dallos, P. Mechanoelectrical transduction of adult outer hair cells studied in a gerbil hemicochlea. Nature 429, 766–770 (2004)

    ADS  CAS  Article  Google Scholar 

  12. Eatock, R. A. Adaptation in hair cells. Annu. Rev. Neurosci. 23, 285–314 (2000)

    CAS  Article  Google Scholar 

  13. Ricci, A. J., Crawford, A. C. & Fettiplace, R. Active hair bundle motion linked to fast transducer adaptation in auditory hair cells. J. Neurosci. 20, 7131–7142 (2000)

    CAS  Article  Google Scholar 

  14. Crawford, A. C. & Fettiplace, R. The mechanical properties of ciliary bundles of turtle cochlear hair cells. J. Physiol. (Lond.) 364, 359–379 (1985)

    CAS  Article  Google Scholar 

  15. Howard, J. & Hudspeth, A. J. Compliance of the hair bundle associated with gating of mechanoelectrical transduction channels in the bullfrog's saccular hair cell. Neuron 1, 189–199 (1988)

    CAS  Article  Google Scholar 

  16. Ricci, A. J., Crawford, A. C. & Fettiplace, R. Mechanisms of active hair bundle motion in auditory hair cells. J. Neurosci. 22, 44–52 (2002)

    CAS  Article  Google Scholar 

  17. Russell, I. J., Kössl, M. & Richardson, G. P. Nonlinear mechanical responses of mouse cochlear hair bundles. Proc. R. Soc. Lond. B 250, 217–227 (1992)

    ADS  CAS  Article  Google Scholar 

  18. van Netten, S. M. & Kros, C. J. Gating energies and forces of the mammalian hair cell transducer channel and related hair bundle mechanics. Proc. R. Soc. Lond. B 267, 1915–1923 (2000)

    CAS  Article  Google Scholar 

  19. Martin, P., Mehta, A. D. & Hudspeth, A. J. Negative hair-bundle stiffness betrays a mechanism for mechanical amplification by the hair cell. Proc. Natl Acad. Sci. USA 97, 12026–12031 (2000)

    ADS  CAS  Article  Google Scholar 

  20. Ricci, A. J., Wu, Y. C. & Fettiplace, R. The endogenous calcium buffer and the time course of transducer adaptation in auditory hair cells. J. Neurosci. 18, 8261–8277 (1998)

    CAS  Article  Google Scholar 

  21. Strelioff, D. & Flock, A. Stiffness of sensory-cell hair bundles in the isolated guinea pig cochlea. Hear. Res. 15, 19–28 (1984)

    CAS  Article  Google Scholar 

  22. Géléoc, G. S., Lennan, G. W., Richardson, G. P. & Kros, C. J. A quantitative comparison of mechanoelectrical transduction in vestibular and auditory hair cells of neonatal mice. Proc. R. Soc. Lond. B 264, 611–621 (1997)

    ADS  Article  Google Scholar 

  23. Langer, M. G. et al. Lateral mechanical coupling of stereocilia in cochlear hair bundles. Biophys. J. 80, 2608–2621 (2001)

    ADS  CAS  Article  Google Scholar 

  24. Rzadzinska, A., Schneider, M. E., Davies, C., Riordan, G. P. & Kachar, B. An actin molecular treadmill and myosins maintain stereocilia functional architecture and self-renewal. J. Cell Biol. 164, 887–897 (2004)

    CAS  Article  Google Scholar 

  25. Kros, C. J. et al. Reduced climbing and increased slipping adaptation in cochlear hair cells of mice with Myo7a mutations. Nature Neurosci. 5, 41–47 (2002)

    CAS  Article  Google Scholar 

  26. Müller, M. Frequency representation in the rat cochlea. Hear. Res. 51, 247–254 (1991)

    Article  Google Scholar 

  27. Assad, J. A. & Corey, D. P. An active motor model for adaptation by vertebrate hair cells. J. Neurosci. 12, 3291–3309 (1992)

    CAS  Article  Google Scholar 

  28. Dallos, P. & Evans, B. N. High frequency outer hair cell motility: corrections and corrigendum. Science 268, 1420–1421 (1995)

    ADS  CAS  Article  Google Scholar 

  29. Santos-Sacchi, J. On the frequency limit and phase of outer hair cell motility: effects of the membrane filter. J. Neurosci. 12, 1906–1916 (1992)

    CAS  Article  Google Scholar 

  30. Preyer, P., Renz, S., Hemmert, W., Zenner, H.-P. & Gummer, A. W. Receptor potential of outer hair cells isolated from base to apex of the adult guinea pig cochlea: implications for cochlear tuning mechanisms. Aud. Neurosci. 2, 145–157 (1996)

    Google Scholar 

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This work was supported by a grant to R.F. from the National Institutes on Deafness and other Communicative Disorders (NIH).

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Correspondence to R. Fettiplace.

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Kennedy, H., Crawford, A. & Fettiplace, R. Force generation by mammalian hair bundles supports a role in cochlear amplification. Nature 433, 880–883 (2005).

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