Neural Encoding and Auditory Perception in Cochlear Implant

项目总结/摘要 65岁或以上的人工耳蜗植入体（CI）使用者通常表现出较差的言语感知 性能比年轻的成年CI用户，特别是在竞争的背景噪音。底层 机制尚不清楚。尽管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。结果是 对于老年植入患者，没有优化程控设置或中断策略的稳健指标。 本研究旨在更好地了解言语知觉的神经生理机制 老年CI用户的缺陷。年长的听众被认为有时间处理缺陷， 对于区分CI用户的语音尤其重要。因此，拟议的研究将侧重于 比较外周和中枢听觉神经对时间包络的编码和感知灵敏度 年轻和年长的成年CI用户之间的线索。目标1将评估时间上的组差异 年轻（< 60岁）和老年（65 - 85岁）成人CI的听神经反应性 用户.将对听神经的三个时间特性进行组比较： 神经适应、适应恢复和幅度调制编码的准确性。目标2将评估 在听觉皮层（即皮层编码）的神经表征和感知的组差异 敏感性，时间间隔和声音开始时间，以及它们与言语感知的关系， 年轻和年长的成年CI用户。目标3将评估AN时间差异的贡献 反应和皮层编码的时间差距和幅度调制的变化，知觉 个别成年CI用户的包络敏感性。对于目标2和3的实验，心理物理程序 将结合外周和中枢产生的诱发电位的电生理测量 并在相同的CI用户中一致应用。此外，认知功能将被评估并作为一个 行为结果的预测因素。本研究结果从两个基本方面都具有实质性意义 科学和临床管理的观点。例如，这些结果将提供有关 外周与中枢听觉功能的贡献，以及听觉与认知因素对知觉的影响。 对时间间隔和振幅调制的敏感性，这对于理解潜在的 这些听觉过程的机制。这些结果还将提供有关是否 在老年CI使用者中，神经编码和电听觉处理的准确性下降， 听觉系统的水平，这种下降，如果有的话，存在。这些信息可能会导致开发 早期识别可能需要额外康复策略的老年CI患者的客观工具。 鉴于时间处理对言语感知的重要性，以及老年人数量的迅速增加， 本申请中提出的CI患者的实验具有很高的科学和转化意义。

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.