Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
School of Engineering, College of Science and Engineering, San Francisco State University, San Francisco, California 94132, USA.
Phys Rev Lett. 2019 Jan 18;122(2):028101. doi: 10.1103/PhysRevLett.122.028101.
Stereociliary imprints in the tectorial membrane (TM) have been taken as evidence that outer hair cells are sensitive to shearing displacements of the TM, which plays a key role in shaping cochlear sensitivity and frequency selectivity via resonance and traveling wave mechanisms. However, the TM is highly hydrated (97% water by weight), suggesting that the TM may be flexible even at the level of single hair cells. Here we show that nanoscale oscillatory displacements of microscale spherical probes in contact with the TM are resisted by frequency-dependent forces that are in phase with TM displacement at low and high frequencies, but are in phase with TM velocity at transition frequencies. The phase lead can be as much as a quarter of a cycle, thereby contributing to frequency selectivity and stability of cochlear amplification.
在听骨膜（TM）中的立体纤毛印痕被视为外毛细胞对 TM 剪切位移敏感的证据，这在外毛细胞通过共振和行波机制对耳蜗敏感性和频率选择性起关键作用。然而，TM 高度水合（按重量计 97%的水），这表明 TM 即使在单细胞水平上也可能具有柔韧性。在这里，我们表明，与 TM 接触的微尺度球形探针的纳米级振荡位移受到与 TM 位移在低频和高频时同相但在过渡频率时与 TM 速度同相的频率相关力的抵抗。相位超前可以达到四分之一周期，从而有助于频率选择性和耳蜗放大的稳定性。
