Investigating the hair-bundle state space in an exploration of inner ear tuning

描述（由申请人提供）：噪声性、药物性和先天性听力损失是由内耳感觉受体毛细胞损伤引起的。75岁以上的美国人中有一半患有中度至重度听力障碍，全球年轻人中听力障碍的患病率上升，听力损失是一个重大的公共卫生问题。了解毛细胞的正常运作，包括它的机械天线，毛发束，将有助于理解听力损失的病理生理学和开发治疗方法。提出的研究旨在检查头发束的动力特性，这是其放大机械刺激能力的基础。作为一个

DESCRIPTION (provided by applicant): Noise-induced, drug-induced, and congenital hearing loss results from damage to hair cells, the sensory receptors of the inner ear. With half of Americans over 75 afflicted by moderate to severe hearing impairment and a worldwide rise in the prevalence of hearing impairment in younger adults, hearing loss is a significant public-health concern. Knowledge of the normal operation of the hair cell-including that of its mechanical antenna, the hair bundle-will contribute to understanding the pathophysiology of hearing loss and developing treatments for it. The proposed study seeks to examine the dynamical properties of a hair bundle that underlie its ability to amplify mechanical stimuli. As a dynamical system, the activity of a hair bundle can be characterized by a state space that describes the bundle's behavior under various conditions. Included in the state space is a Hopf bifurcation, an instability that endows the hair bundle with the ability to self-tune near criticalty. This dynamical system can be readily explored by manipulation of two control parameters, offset force and stiffness. I will attempt to coerce the hair bundle to cross its critical point, demonstrating for the first time the presence of a Hopf bifurcation embedded in hair-bundle mechanics. This demonstration will provide a tool for further investigation of phenomena characteristic of the active process in hearing. Thus, by controlling mechanical properties, I shal elucidate the functions of hair bundles that endow humans with highly resolved auditory sensation.