Neural and Perceptual Mechanisms for Coding Frequency Modulation

调频(FM)提供语音和音乐中的关键信息，这意味着 调频信号的神经编码和感知是人类交流的基础。类似地，双耳信息 通过允许我们定位声音并在空间上隔离，帮助我们在复杂的日常环境中导航 分开的消息来源。调频和双耳知觉都会随着年龄的增长而恶化，这是无法解释的 因为听力损失，这表明某种程度的衰老效应是由听觉大脑的变化驱动的。在……里面 此外，轻度认知障碍(MCI)和阿尔茨海默病(AD)患者的双耳听力较差 处理和噪声中的语音感知。目前的提议将检验这样一种假设，即一些 患有MCI和AD的人在导航复杂的听觉场景时遇到的挑战可能是 这是由听觉编码的潜在退化造成的，而不是由于记忆障碍和 全面性认知能力下降。阿尔茨海默病及相关疾病患者听觉脑老化加剧 痴呆症已被证明伴随着知觉困难。MCI是MCI的前驱阶段 AD是研究AD早期神经和知觉标记物的好时机。有一个关键的问题 需要在MCI患者中进行心理物理实验，仔细控制记忆和任务需求， 特别是考虑到了解AD的神经机制和预防AD的长期潜力 进一步下降的进程。这项拟议的研究将是对单声道和 MCI中的双耳调频和调幅(AM)感知，并将测试感知是否存在差异 受具有和不具有时间精细结构(TFS)提示的刺激的影响。我们将专门测试那些 因AD而被诊断为MCI，具有AD生物标记物以及年龄和听力匹配 控制。Aim 1将使用单耳刺激来评估调制知觉 以最佳方式执行任务。我们将测试MCI是否与FM特有的缺陷有关 根据年龄、听力损失和任务要求进行解释。我们将使用一种新颖的AM刺激来模拟 FM感知的影响，但不存在TFS线索，以评估单耳TFS与TFS的作用 信封(ENV)编码，以MCI表示。目标2将通过测试双耳或双耳进一步探测中枢听觉系统 以前在MCI中发现的损害是由TFS或ENV的双耳处理或由更高水平的 约束条件。这一结果将提供第一个针对特定目标的MCI听觉编码的严格测试 听觉机制(ENV与TFS处理)，并比较依赖于一只耳朵和两只耳朵的测量。 研究结果将为更大规模的听觉神经编码研究提供初步数据和基础 并通过AD的早期和更高级阶段的认知变化，这是PI的关键机会 将她的研究范围扩大到听觉感知和认知的相互作用。这些发现也将有助于 为AD寻找一种早期的、负担得起的和可获得的感知标记。

Frequency modulation (FM) provides critical information in both speech and music, meaning that accurate neural encoding and perception of FM is essential for human communication. Similarly, binaural information helps us navigate complex everyday environments by allowing us to localize sounds and segregate spatially separated sources. Both FM and binaural perception worsen with age in a manner that cannot be accounted for by hearing loss, suggesting some degree of aging effects are driven by changes in the auditory brain. In addition, people with mild cognitive impairment (MCI) and Alzheimer’s Disease (AD) exhibit poor binaural processing and speech-in-noise perception. The present proposal will test the hypothesis that some of the challenges experienced by people with MCI and AD when navigating complex auditory scenes can be accounted for by underlying degradation in auditory encoding, beyond what is due to memory impairment and general cognitive decline. Exacerbated aging effects in the auditory brain in people with AD and related dementias have been shown to be concomitant with difficulties in perception. MCI is the prodromal phase of AD, and an opportune stage for investigating early neural and perceptual markers of AD. There is a critical need for psychophysical experiments in MCI patients that carefully control for memory and task demands, especially given the long-term potential for understanding the neural mechanisms of AD and preventing the progression of further decline. The proposed research will be the first characterization of monaural and binaural FM and amplitude modulation (AM) perception in MCI and will test whether perception is differentially impacted for stimuli with and without temporal fine structure (TFS) cues. We will specifically test people who have been diagnosed with MCI due to AD with AD biomarkers as well as age- and audiometrically matched controls. Aim 1 will assess modulation perception using diotic stimuli where a single ear can be used to perform the task optimally. We will test whether MCI is associated with an FM-specific deficit beyond what can be explained by age, hearing loss, and task demands. We will use a novel, AM stimulus that simulates the effects of FM perception, but without the presence of TFS cues, to assess the role of monaural TFS versus envelope (ENV) coding in MCI. Aim 2 will further probe the central auditory system by testing whether binaural impairments previously found in MCI are driven by binaural processing of TFS or ENV, or by higher-level constraints. The results will provide the first rigorous test of auditory encoding in MCI that targets specific auditory mechanisms (ENV vs. TFS processing) and compares measures that rely on one versus two ears. Results will provide the preliminary data and foundation for larger-scale studies on how auditory neural coding and perception change through early and more advanced stages of AD, and is a key opportunity for the PI to expand her research scope to the interaction of auditory perception and cognition. Findings will also contribute to the search for an early, affordable, and accessible perceptual marker for AD.