Details

Autor(en) / Beteiligte

• Nowotny, Manuela
• Gummer, Anthony W.

Titel

Nanomechanics of the Subtectorial Space Caused by Electromechanics of Cochlear Outer Hair Cells

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 2006-02, Vol.103 (7), p.2120-2125

Ort / Verlag

United States: National Academy of Sciences

Erscheinungsjahr

2006

Quelle

MEDLINE

Beschreibungen/Notizen

• The stereocilia of the cochlear inner hair cells (IHCs) transduce vibrations into the sensory receptor current. Until now, mechanisms for deflecting these stereocilia have not been identified experimentally. Here, we identify a mechanism by using the electromechanical properties of the soma of the outer hair cell to produce an intracochlear, mechanical force stimulus. It is known that the soma of this cell generates mechanical force in response to a change of its transmembrane potential. In the present experiments, the force was induced by intracochlear electrical stimulation at frequencies that covered the entire functionally relevant range of 50 kHz. Vibration responses were measured in the transverse direction with a laser Doppler vibrometer. For frequencies up to ≈3 kHz in the first three turns of the guinea-pig cochlea, the apical surface of the IHC and the opposing surface of the tectorial membrane were found to vibrate with similar amplitudes but opposite phases. At high frequencies, there was little relative motion between these surfaces in the transverse direction. The counterphasic motion up to ≈3 kHz results in a pulsatile motion of the fluid surrounding the stereocilia of the IHCs. Based on physical principles of fluid flow between narrowly spaced elastic plates, we show that radial fluid motion is amplified relative to transverse membrane motion and that the radial motion is capable of bending the stereocilia. In conclusion, for frequencies up to at least 3 kHz, there appears to be direct fluid coupling between outer hair cells and IHCs.