Behavioral and Cortical Signatures of Reduced Auditory Spatial Tuning with Age

描述(由申请人提供)：在70岁以上的成年人中，具有临床意义的听力损失的患病率约为63%(Lin等人，2011年)。此外，老年人中未经治疗的听力损失与认知能力下降更快和患痴呆症的风险更大有关(Lin等人，2013年)。在嘈杂的环境中难以跟上对话是最常见的与听力有关的抱怨，无论听觉是否通过放大来补偿。在存在相互竞争的声音的情况下，人类必须专注于期望的声源(例如，语音、音乐、环境声音)的非凡能力在很大程度上取决于空间听觉。众所周知，随着正常年龄的增长，空间听力的许多方面都会下降，但导致这种下降的机制尚不清楚。同样，众所周知，包括集中注意在内的自上而下的感觉加工控制会随着年龄的增长而下降，但选择性听觉空间注意的年龄相关变化还没有很好的文献记录，也很少被理解。这个项目的目标是利用同步的脑电和行为测量，调查老年听者在听觉空间调谐中涉及的过程。实验被设计用来评估特定的假说，这些假说与空间加工背后的对手通道(OC)机制的潜在变化有关。实验重点放在低频刺激上，因为~1500赫兹以下的空间线索主要是耳间时差，而时序缺陷是老年性耳聋的标志。目标1的一个目标是确定年龄较大的听者(听力正常)是否表现出相对于年轻听者的空间调谐改变。第二个目标是使用空间调整措施来 评估OC模型背后的潜在机制，以及与年龄相关的抑制下调和/或时间精确度对空间加工缺陷的潜在影响。在目标2中，平行实验被用来探索这样一种可能性，即随着年龄的增长，扩大的空间注意力进一步限制了年长听者所能获得的空间优势。在……里面 此外，这项工作的长期目标是确定适当的诊断方法和补救目标，评估并可能改变听力增强设备和听觉训练方法用于改善现有缺陷的方式，以及在发现减缓或逆转年龄相关性听力损失的治疗方法时开发有用的结果度量标准。概述的培训计划提供了一个强大的指导环境，无论是直接的实验室环境还是机构环境。奖学金申请者决心努力建立必要的工具和经验，以便在未来过渡到独立的学术研究生涯。

DESCRIPTION (provided by applicant): The prevalence of clinically-significant hearing loss is ~63% in adults over 70 years of age (Lin et al., 2011). Moreover, untreated hearing loss in older adults has been linked to more rapid cognitive declines and greater risk of dementia (Lin et al., 2013). Difficulty following conversations in noisy settings is the most common hearing-related complaint, regardless of whether audibility is compensated by amplification. The remarkable ability humans have to focus on a desired sound source (e.g., speech, music, environmental sounds) in the presence of competing sounds depends to a large extent on spatial hearing. It is known that many aspects of spatial hearing decline with normal aging but the mechanisms responsible for that decline are not known. Likewise, it is known that top-down control of sensory processing, including focused attention, declines with age but age-related changes in selective auditory spatial attention have not been well documented and are poorly understood. The goal of this project is to investigate the processes involved in auditory spatial tuning in oldr listeners, leveraging simultaneous electroencephalography and behavioral measurements. Experiments have been designed to evaluate specific hypotheses associated with potential changes in the opponent- channel (OC) mechanisms underlying spatial processing. The experiments focus on low-frequency stimuli, since spatial cues below ~1500 Hz are dominated by interaural time differences, and timing deficits are a hallmark of presbycusis. A goal of Aim 1 is to determine whether or not older listeners (with normal hearing sensitivity) exhibit altered spatial tuning relative to younger listeners. A second goal is to use measures of spatial tuning to evaluate the potential mechanisms underlying the OC model and the potential influence of either age-related down-regulation of inhibition and/or temporal precision on spatial processing deficits. In Aim 2, parallel experiments are used to probe the possibility that, with advancing age, broadened spatial attention further limits spatial advantages available to older listeners. In addition, long-term goals of this work are to identify appropriate diagnostic methods and remediation targets, to evaluate and possibly alter the way hearing enhancement devices and auditory training methods may be used to ameliorate existing deficits, and to develop outcome metrics useful should treatments that slow or reverse age-related hearing loss be discovered. The training program outlined provides a strong mentoring environment both from an immediate laboratory setting as well as the institutional setting. The fellowship applicant is determined to work towards establishing the tools and experience necessary to transition in the future to an independent academic research career.