Braun M
Hear Res. 1994 Jul;78(1):98-114. doi: 10.1016/0378-5955(94)90048-5.
A cochlear model is presented suggesting that the organ of Corti (OC) and the basilar membrane (BM) are both tuned resonant systems, but have different functions. The OC provides frequency filtering and amplification by means of tuned outer hair cells. The BM provides resonant absorption of excessive vibrational energy as an overload protection for vulnerable elements in the OC. Evidence supporting this model is demonstrated in dolphins, bats, and desert rodents. Specialized auditory capabilities correlate with cochlear deviations, some of them dramatically changing BM compliance. In characteristic regions along the cochlea there are BM thickenings and, on both sides of the OC, hypertrophied supporting cells. Structures of striking similarity have evolved independently across orders or families, revealing multiple events of convergent evolution. In all cases, the locations of deviating structures rule out a BM function in auditory frequency selectivity but support one in resonant absorption. Cochlear microphonics and BM responses demonstrate strongest high-level absorption in the frequency bands most vital for the tested species. The assumed cause is increased internal damping in the enlarged structures during BM motion. Species with intermediate specializations supply further evidence that resonant absorption is universally the genuine function of BM mechanics in mammals, providing complementary high-level protection of low-level sensitivity.
提出了一种耳蜗模型，表明柯蒂氏器（OC）和基底膜（BM）都是调谐共振系统，但功能不同。OC通过调谐的外毛细胞提供频率滤波和放大。BM提供对过量振动能量的共振吸收，作为对OC中脆弱元件的过载保护。在海豚、蝙蝠和沙漠啮齿动物中证明了支持该模型的证据。专门的听觉能力与耳蜗偏差相关，其中一些偏差会显著改变BM的顺应性。在沿耳蜗的特征区域存在BM增厚，并且在OC的两侧有肥大的支持细胞。惊人相似的结构在不同的目或科中独立进化，揭示了多次趋同进化事件。在所有情况下，偏离结构的位置排除了BM在听觉频率选择性方面的功能，但支持其在共振吸收方面的功能。耳蜗微音电位和BM反应表明，在对受试物种最重要的频段中，存在最强的高水平吸收。假定的原因是BM运动期间扩大结构中的内部阻尼增加。具有中间特化的物种提供了进一步的证据，表明共振吸收普遍是哺乳动物中BM力学的真正功能，为低水平敏感性提供互补的高水平保护。
