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，临床显著性听力损失的患病率约为63% （Lin et al., 2011）。此外，未经治疗的老年人听力损失与更快的认知能力下降和更大的痴呆风险有关（Lin et al., 2013）。在嘈杂的环境中难以跟上谈话是最常见的听力相关抱怨，无论是否通过扩音来补偿可听性。人类在存在竞争声音的情况下专注于所需声源（如演讲、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，空间听力的许多方面随着正常衰老而下降，但导致这种下降的机制尚不清楚。同样，我们知道，自上而下的感觉处理控制，包括集中注意力，随着年龄的增长而下降，但与年龄相关的选择性听觉空间注意力的变化还没有得到很好的记录，也没有得到很好的理解。这个项目的目标是利用同步脑电图和行为测量来研究老年听众的听觉空间调谐过程。实验被设计来评估与潜在的空间加工对手通道（OC）机制的潜在变化相关的特定假设。实验集中在低频刺激上，因为低于~ 1500hz的空间线索主要由耳间时差主导，而时间缺陷是老年性痴呆的一个标志。Aim 1的目标是确定老年听众（听力灵敏度正常）是否表现出相对于年轻听众的空间调谐改变。第二个目标是使用空间调谐的度量

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.