Forward and Reverse Travelling Waves in the Cochlea

耳蜗是内耳的一个复杂结构，它包含一层弹性膜，即基底膜，基底膜响应声音而振动。这种振荡刺激被称为毛细胞的机械感觉细胞，它将信号发送到听神经。大约15年前的一项重大发现表明，一组毛细胞，即外毛细胞，本身可以表现出运动性，因此可以作为调节耳蜗灵敏度的机电元件。作为该功能的副产品，外毛细胞的活动以声能的形式传回耳朵，产生可测量的声音，称为耳声发射，这已被科学家和临床医生用作研究耳蜗功能的非侵入性工具。本项目利用电生理学、计算机模拟和耳声发射测量来检验关于基底膜振动和外毛细胞活动如何参与正常耳蜗功能的几个新假设。它将具体评估非线性放大发生在耳蜗的位置，以及基底膜是否可能具有不同于经典行波形式的振荡模式。这种独特的生理和建模结合方法的结果将对所有听觉神经科学产生影响，新的发现将不仅对听力障碍的处理产生重要影响，而且对听觉交流的设计，以及生物力学和生物工程产生重要影响。＊＊＊

9320326 Mountain The cochlea is the complex structure in the inner ear that contains an elastic membrane, the basilar membrane, which oscillates in response to sound. The oscillations stimulate mechanosensory cells called hair cells, which send signals to the auditory nerve. A remarkable finding around 15 years ago showed that one group of hair cells, the outer hair cells, can themselves show motility, and so act as electromechanical elements that can modulate cochlear sensitivity. As a byproduct of that function, the outer hair cell activity is transmitted as acoustical energy back out of the ear, producing measurable sounds called otoacoustic emissions, which have been used by scientists and clinicians as a non-invasive tool to study cochlear function. This project uses electrophysiology, computer simulation, and measurements of the otoacoustic emissions to examine several novel hypotheses about how the basilar membrane vibration and the outer hair cell activity may be involved in normal cochlear function. It will specifically evaluate where the non-linearities in amplification occur in the cochlea, and whether the basilar membrane may have modes of oscillation different from the classical traveling-wave form. Results from this unique combined physiological and modeling approach will have an impact on all auditory neuroscience, and novel findings will have important impact not only on handling of hearing disorders, but on design of auditory communications, and on biomechanics and bioengineering. ***