Neural and Perceptual Mechanisms for Coding Frequency Modulation

调频（FM）在语音和音乐中提供关键信息，这意味着准确的 FM的神经编码和感知对于人类交流是必不可少的。类似地，双耳信息 帮助我们在复杂的日常环境中导航，使我们能够定位声音并在空间上隔离 分离的来源。FM和双耳感知都随着年龄的增长而恶化，其方式无法解释 这表明一定程度的衰老效应是由听觉大脑的变化驱动的。在 此外，患有轻度认知障碍（MCI）和阿尔茨海默病（AD）的人表现出较差的双耳听力。 处理和噪声中的语音感知。本提案将检验以下假设： MCI和AD患者在导航复杂的听觉场景时所经历的挑战可能是 由于听觉编码的潜在退化，超出了记忆障碍的范围， 认知能力普遍下降AD患者听觉脑的老化效应加重及相关 痴呆症已被证明是伴随着感知困难的。MCI是MCI的前驱期， AD，并为研究AD的早期神经和感知标志物提供了一个合适的阶段。存在一个临界 需要在MCI患者中进行心理物理实验，仔细控制记忆和任务要求， 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。拟议的研究将是第一个表征单声道和 双耳FM和调幅（AM）感知MCI，并将测试感知是否差异 影响的刺激和没有时间精细结构（TFS）线索。我们将专门测试那些 已被诊断患有由于AD导致的MCI，具有AD生物标志物以及年龄和听力匹配 对照目标1将评估调制知觉使用diotic刺激，其中一个单一的耳朵可以用来 以最佳方式执行任务。我们将测试MCI是否与FM特异性缺陷相关， 可以用年龄、听力损失和任务要求来解释。我们将使用一种新颖的AM刺激， FM感知的影响，但没有TFS线索的存在，以评估单耳TFS与 MCI中的包络（ENV）编码。Aim 2将通过测试双耳 先前在MCI中发现的损伤是由TFS或ENV的双耳处理或更高水平的 约束结果将提供MCI中听觉编码的第一个严格测试， 听觉机制（ENV与TFS处理），并比较了依赖于一只耳朵与两只耳朵的措施。 这些结果将为更大规模的研究听觉神经编码的机制提供初步的数据和基础 和认知变化，通过早期和更先进的阶段，AD，是一个关键的机会，PI， 将她的研究范围扩展到听觉感知和认知的相互作用。调查结果也将有助于 寻找一个早期的，负担得起的，和可访问的感知标记为AD。

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.