Neural Encoding and Auditory Perception in Cochlear Implant

项目摘要/摘要 65岁或以上的人工耳蜗(CI)使用者通常表现出较差的言语感知能力 比年轻的成年CI用户表现更好，特别是在竞争背景噪音中。潜在的 机制仍不清楚。虽然认知功能下降被认为是主要因素， 听觉系统的恶化也被认为是主要原因。因此，有 没有可靠的指标来优化老年植入患者的编程设置或康复策略。 这项研究旨在更好地了解言语感知的潜在神经生理机制。 较老CI用户的缺陷。众所周知，年长的听者有时间处理缺陷，以及时间线索 对于识别CI用户的语音尤其重要。因此，拟议的研究将集中于 比较外周和中枢听神经对时间包络的编码和感知敏感度 年轻人和老年人之间的提示CI用户。目标1将评估群体在时间上的差异 青年(60岁)和老年(65-85岁)成人CI的听神经反应性 用户。这组人将对听神经的三个时间特性进行比较：周围刺激 神经适应、适应恢复和调幅编码的准确性。目标2将评估 在听觉皮质(即皮层编码)和知觉的神经表征的组差异 时间间隔和发声时间的敏感度及其与言语知觉的关系 更年轻和更年长的成年CI用户。目标3将在时间上评估差异的贡献 时间间隔和幅度调制对知觉变化的反应和皮层编码 个别成年CI用户的信封敏感性。对于目标2和3中的实验，心理物理程序 外周和中枢诱发电位的电生理测量将结合起来 并在同一CI用户中协同应用。此外，认知功能将作为一个整体进行评估和使用 行为结果的预测者。本研究的结果从两个基本方面都具有实质性的意义 科学和临床管理的观点。例如，这些结果将提供有关 外周和中枢听觉功能以及听觉和认知因素对知觉的贡献 对时间间隔和幅度调制的敏感性，这对于理解潜在的 这些听觉过程的机制。这些结果还将提供以下信息： 在老年CI使用者中，神经编码和电听力处理的准确性下降，以及 听觉系统的水平这种下降，如果有的话，是存在的。这些信息可能会导致开发 目的为早期识别可能需要额外康复策略的老年CI患者提供工具。 鉴于时间处理对语音感知的重要性以及老年人数量的迅速增加 对于CI患者，本申请中提出的实验具有很高的科学意义和翻译意义。

PROJECT SUMMARY/ABSTRACT Cochlear implant (CI) users who are 65 years or older typically show poorer speech perception performance than younger adult CI users, especially in competing background noise. The underlying mechanisms remain unclear. Whereas declined cognitive function has been proposed as the major factor, deteriorations in the auditory system have also been suggested to be the primary reason. As a result, there is no robust indicator for optimizing programming settings or habilitation strategies for older implanted patients. This study is designed to better understand underlying neurophysiological mechanisms of speech perception deficits in older CI users. Older listeners are known to have temporal processing deficits, and temporal cues are particularly important for discriminating speech in CI users. Therefore, the proposed study will focus on comparing peripheral and central auditory neural encoding of, and perceptual sensitivity to, temporal envelope cues between younger and older adult CI users. Aim 1 will assess group differences in temporal responsiveness of the auditory nerve in younger (< 60 years) and older (between 65 and 85 years) adult CI users. The group comparison will be done for three temporal properties of the auditory nerve: peri-stimulus neural adaptation, adaptation recovery and the accuracy of amplitude modulation encoding. Aim 2 will assess group differences in neural representation at the auditory cortex (i.e. cortical encoding) of, and perceptual sensitivity to, temporal gaps and voice onset time, as well as their association with speech perception in younger and older adult CI users. Aim 3 will evaluate contributions of differences in AN temporal responsiveness and cortical encoding of temporal gaps and amplitude modulation to variations in perceptual envelope sensitivity in individual adult CI users. For experiments in Aims 2 and 3, psychophysical procedures and electrophysiological measures of peripherally and centrally generated evoked potentials will be combined and applied in concert in the same CI users. In addition, cognitive functions will be evaluated and used as one of the predictors for behavioral results. Results of this study have substantial significance from both a basic science and a clinical management point of view. For example, these results will provide information about the contributions of peripheral vs central auditory functions, as well as auditory vs cognitive factors to perceptual sensitivity to temporal gaps and amplitude modulations, which is crucial for understanding underlying mechanisms of these auditory processes. These results will also provide information about whether the accuracy of neural encoding and processing of electrical hearing declines in older CI users, as well as at which level of the auditory system this decline, if any, exists. This information could potentially lead to developing objective tools for early identification of older CI patients who may need additional rehabilitation strategies. Given the importance of temporal processing for speech perception and the rapidly increasing number of older CI patients, experiments proposed in this application are of high scientific and translational significance.