Biophysical Mechanisms Underlying Auditory Transduction

耳朵是一个非凡的探测器：它具有高度的灵敏度和选择性，并且在超过12个数量级的大动态范围内工作。然而，对耳朵的直接生理研究一直很困难，因此我们对耳朵中起作用的（基于细胞的复杂阵列）放大机制知之甚少。听力障碍通常是由这些过程中的问题引起的，并影响了相当一部分加拿大人的生活质量。幸运的是，我们可以利用耳朵的另一个非凡特性：它不仅对声音有反应，而且还能发出声音。这些声音被称为耳声发射（oae），可以自发产生，也可以由外部刺激引起，可以使用灵敏的麦克风在耳道内无创地测量。在科学和临床环境中（例如，听力障碍筛查），耳廓声发射都取得了巨大的成功，进一步的研究将有助于明确我们对耳内放大的基本生物物理学的理解。****该研究的目的是针对表征声发射产生机制及其与耳朵的感觉细胞如何将声音信息编码到大脑的关系。该项目主要关注蜥蜴，并将实验与数学建模相结合，其目标将解决目前处于基础听觉科学核心的几个基本问题。尽管与哺乳动物相比，蜥蜴的形态和生理相对简单，但蜥蜴的耳朵具有许多更复杂动物的共同功能特征（例如，低阈值，尖锐调谐，强大的oae）。因此，蜥蜴耳朵的简单性在我们试图阐明许多被认为对脊椎动物听觉功能至关重要的潜在生物物理过程时，可以成为我们的优势。因此，这里提出的工作将最终建立在我们对人类听觉功能的了解之上，并为加拿大成为听力研究的国际领导者做出贡献。******

The ear is a remarkable detector: It is both highly sensitive and selective, and operates over a large dynamic range spanning more than 12 orders of magnitude. Direct physiological study of the ear however has been difficult, and thus there is much we do not know about the [complex array of cellular-based] amplification mechanisms at work in the ear. Hearing impairment commonly arises due to problems with these processes and affects the quality of life for a significant fraction of Canadians. Fortunately, we can make use of another extraordinary property of the ear: Not only does it respond to sound but emits it as well. These sounds, known as otoacoustic emissions (OAEs), can arise either spontaneously or be evoked by an external stimulus and are measurable non-invasively in the ear canal using a sensitive microphone. OAEs have been employed with great success in both scientific and clinical contexts (e.g., screening for hearing impairment) and further study will help crystallize our understanding of the fundamental biophysics underlying amplification in the ear.****The aims of the study are targeted towards characterizing OAE generation mechanisms and their relationship to how the sensory cells of the ear encode sound information to the brain. Focusing primarily on lizards and combining experiment with mathematical modeling, the project's objectives will address several fundamental questions currently at the heart of basic auditory science. Despite the relative simplicity of their morphology and physiology when compared to mammals, lizard ears share many of the functional features common to more complex animals (e.g., low thresholds, sharp tuning, robust OAEs). Thereby, the simplicity of the lizard ear can be used to our advantage when trying to clarify many of the underlying biophysical processes believed crucial in vertebrate auditory function. Thus, the work proposed here will ultimately build on our knowledge of auditory function in humans and contribute towards Canada being an international leader in the study of hearing.******