Criticality and Active Dynamics in Mechanical Detection by the Inner Ear

听觉(听觉)和前庭(平衡)系统为我们提供了关于周围世界的丰富信息。为了实现这一点，这些感官系统执行非凡的机械检测，对内耳毛细胞中非常微小的运动做出反应。即使在嘈杂的环境中，也必须达到这种敏感性，以便使个人能够将他们想要听到和解释的声音与背景噪音区分开来。虽然听力的基本过程是已知的，但支持听力敏锐度(能够清楚地检测出重要声音)的过程还没有被很好地理解。这个项目将着眼于毛细胞反应的基本力学和物理学，以便更好地理解听力过程的动力学。除了促进对这一重要生理过程的理解外，从研究中获得的知识还可能为模拟耳朵过程的传感器系统的开发提供信息。该奖项将允许纳入本科生研究人员，他们是通过扩大来自代表性不足的少数族裔的学生的参与而招募的。该实验室还将把高中生纳入研究项目，重点是鼓励女性在这一领域继续学习。该项目有两个指导性假设。首先，毛细胞之间的耦合改变了系统的动态，使其更接近临界点。其次，耦合系统中弱混沌的存在提高了系统的灵敏度。为了研究这些假设，这个项目将使用牛蛙球囊的体外准备来评估耦合的发束系统如何实现它们的检测。具体地说，这项研究将寻找关键的签名，这将是一种导致高度敏感的反应和广泛的幂定律行为的制度。该项目还将探索混沌动力学在完全耦合系统中的作用，以确定耦合如何改变单个束中的混沌，以及它如何影响整个系统的性能。为了阐明这些动态机制的作用，该项目将使用包含不同耦合条件的准备工作。在一组实验中，它将使用混合制剂，将不同数量的发束连接起来，建立不同大小的阵列。在另一组实验中，将使用半完整的系统，保存固有的覆盖膜。研究人员假设，系统处于接近临界点的弱振荡侧，临界振荡表现出混沌的动力学。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The auditory (hearing) and vestibular (balance) systems provide us with rich information about the world around us. To achieve this, these sensory systems perform remarkable mechanical detection, responding to very small movements in the hair cells of the inner ear. This sensitivity has to be achieved even in a noisy environment in order to allow individuals to distinguish sounds that they want to hear and interpret from background noise. While the fundamental process of hearing is known, the processes that support acuity of hearing (being able to clearly detect the important sounds) are not well understood. This project will look at the fundamental mechanics and physics of the response of hair cells in order to better understand the dynamics of the hearing process. Beyond advancing understanding of this important physiological process, the knowledge gained from the research may also inform the development of sensor systems that mimic the process of the ear. The award will enable the inclusion of undergraduate researchers, recruited through programs that broaden the participation of students from under-represented minorities. The laboratory will also include high school students in the research project, focusing on encouraging women to pursue studies in this field.This project has two guiding hypotheses. First, that the coupling between hair cells changes the dynamics of the system, poising it closer to criticality. Second, that the presence of weak chaos in the coupled system enhances its sensitivity. In order to investigate thse hypotheses, this project will use in vitro preparations of the bullfrog sacculus to assess how coupled systems of hair bundles achieve their detection. Specifically, the research will look for signatures of criticality, which would be a regime that leads to a highly sensitive response and a broad range of power-law behavior. The project will also explore the role of chaotic dynamics in the fully coupled system in order to determine how chaoticity in individual bundles is modified by the coupling, as well as how it affects the performance of the full system. To elucidate the role of these dynamic regimes, the project will use preparations that incorporate different coupling conditions. For one set of experiments, it will use hybrid preparations, in which different numbers of hair bundles will be connected to build arrays of different sizes. For another set of experiments, semi-intact systems will be used, which preserve the innate, overlying membrane. The researcher hypothesizes that the system is poised near criticality, on the weakly oscillatory side, and that the critical oscillations exhibit chaotic dynamics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.