Department of Biomedical Engineering, University of Rochester, 204 Goergen Hall, Rochester, New York 14627, USA.
Department of Mechanical Engineering, University of Rochester, 212 Hopeman Engineering Building, Rochester, New York 14627, USA.
J Acoust Soc Am. 2018 Feb;143(2):735. doi: 10.1121/1.5023206.
In the mammalian cochlea, the geometrical and mechanical properties of the organ of Corti complex (OCC, consisting of the tectorial membrane, the organ of Corti, and the basilar membrane) have fundamental consequences for understanding the physics of hearing. Despite efforts to correlate the mechanical properties of the OCC with cochlear function, experimental data of OCC stiffness are limited due to difficulties in measurement. Modern measurements of the OCC stiffness use microprobes exclusively, but suffer ambiguity when defining the physiologically relevant stiffness due to the high nonlinearity in the force-displacement relationship. The nonlinearity stems from two sources. First, microprobes apply local force instead of fluid pressure across the OCC. Second, to obtain the functionally relevant stiffness, the OCC is deformed well beyond in vivo levels (>10 μm). The objective of this study was to develop an alternative technique to overcome challenges intrinsic to the microprobe method. Using a custom-designed microfluidic chamber system, hydrostatic pressures were applied to the excised gerbil cochlea. Deformations of the OCC due to hydrostatic pressures were analyzed through optical-axis image correlation. The pressure-displacement relationship was linear within nanoscale displacement ranges (<1 μm). To compare the results in this paper with existing measurements, a three-dimensional finite element model was used.
在哺乳动物耳蜗中，耳蜗器官复合体（OCC，由盖膜、耳蜗和基底膜组成）的几何和机械特性对理解听觉物理学具有重要意义。尽管人们努力将 OCC 的机械特性与耳蜗功能相关联，但由于测量困难，OCC 硬度的实验数据有限。现代 OCC 硬度测量仅使用微探针，但由于力-位移关系的高度非线性，在定义与生理相关的硬度时存在歧义。这种非线性源于两个来源。首先，微探针在 OCC 上施加的是局部力而不是流体压力。其次，为了获得与功能相关的硬度，OCC 的变形远远超出了体内水平（>10 μm）。本研究的目的是开发一种替代技术，以克服微探针方法固有的挑战。使用定制的微流控室系统，向切除的沙鼠耳蜗施加静压。通过光轴图像相关分析来分析 OCC 因静压而产生的变形。在纳米级位移范围内（<1 μm），压力-位移关系呈线性。为了将本文中的结果与现有测量结果进行比较，使用了三维有限元模型。
