Neural Determinants of Age-Related Changes in Cross-Sensory Plasticity and Multisensory Integration Affecting Audiovisual Speech Perception

项目总结 老年人比年轻人更难识别听觉(AO)和视觉(VO)言语。尽管 这些单一感觉缺陷，一些老年人可以像年轻人一样准确地识别视听(AV)言语 成年人。研究发现，老年人表现出更多的跨模式可塑性，多感官整合，以及 额叶-皮质对感觉输入的调节，但这些与年龄相关的变化有益的程度 并解释了老年人保守的AV语音是一个关键的知识鸿沟。建议的目标是 研究计划将使用结合电生理学(EEG)的创新神经系统方法， 结构成像(SMRI)和扩散成像(DKI)，以表征特定的神经机制， 随着年龄的增长而适应，以支持AV语音。将使用结合EEG和sMRI的来源受限分析 计算特定感兴趣区域产生的潜力和区域之间的功能连通性 感兴趣的人。跨模式可塑性的特征是跨感觉反应幅度(视觉诱发 听觉皮层产生的电位和视觉皮层产生的听觉诱发电位)和 听觉和视觉皮质之间的功能连接(目标1)。多感官整合将是 以颞顶皮质产生的房室反应幅度和功能连接性为特征 在顶叶皮质和感觉皮质之间(目标2)。感觉输入的额叶-大脑皮层调节 以额叶下部皮层言语诱发电位为特征，功能性 额叶下部皮质和感觉皮质之间以及额叶下部皮质和感觉皮质之间的连接 颞顶皮质(目标3)。我们假设，与年龄相关的单一感觉缺陷对 通过更多地依赖跨模式可塑性(目标1)、多感官，AV言语感知将得到改善 整合(目标2)和/或感觉输入的额叶-皮质调节(目标3)。通过功能连接 假设是为了促进这些机制中的每一种，并保护老年人的AV言语，年龄- 相关的白质退化(DKI)预计会限制功能连接，因此任何与年龄相关的 功能连接性的增加可能会被白质完整性的年龄相关缺陷所减缓。当我们 假设每种机制本身都可以部分解释一些老年人的保守的AV语音 成年人、个体差异和机制之间的变异性预计可以解释为什么一些老年人 成年人表现出保守的AV言语知觉，而其他人则不是。重要的是，我们还将研究 一些老年人表现出的保守的AV语言在多大程度上转化为更好的感知 日常环境中的言语交流能力，通过自我报告评估来衡量。识别 保护老年人房室语言的重要机制可以阐明新的靶点 帮助保持甚至恢复有感觉障碍的老年人的沟通能力的干预。

PROJECT SUMMARY Older adults have more difficulty than younger adults identifying auditory (AO) and visual (VO) speech. Despite these unisensory deficits, some older adults can identify audiovisual (AV) speech as accurately as younger adults. Older adults have been found to exhibit more cross-modal plasticity, multisensory integration, and frontal-cortical modulation of sensory input, but the extent to which these age-related changes are beneficial and explain the conserved AV speech of older adults is a critical knowledge gap. The aims of the proposed research program will use an innovative neural systems approach incorporating electrophysiology (EEG), structural imaging (sMRI), and diffusion imaging (DKI) to characterize the specific neural mechanisms that adapt with age to support AV speech. Source-constrained analyses incorporating EEG and sMRI will be used to calculate potentials generated in specific regions of interest and the functional connectivity between regions of interest. Cross-modal plasticity will be characterized by cross-sensory response amplitudes (visual-evoked potentials generated in auditory cortex and auditory-evoked potentials generated in visual cortex) and the functional connectivity between auditory and visual cortex (Aim 1). Multisensory integration will be characterized by AV response amplitudes generated in temporoparietal cortex and the functional connectivity between temporoparietal cortex and sensory cortex (Aim 2). Frontal-cortical modulation of sensory input will be characterized by speech-evoked potentials generated in inferior frontal cortex and the functional connectivity between inferior frontal cortex and sensory cortex and between inferior frontal cortex and temporoparietal cortex (Aim 3). We hypothesize that the negative effects of age-related unisensory deficits on AV speech perception will be ameliorated by greater reliance on cross-modal plasticity (Aim 1), multisensory integration (Aim 2), and/or frontal-cortical modulation of sensory input (Aim 3). Though functional connectivity is hypothesized to facilitate each of these mechanisms and conserve the AV speech of older adults, age- related white matter degradation (DKI) is expected to limit functional connectivity, such that any age-related increases in functional connectivity may be moderated by age-related deficits in white mater integrity. While we hypothesize that each mechanism can on its own partially account for the conserved AV speech of some older adults, individual differences and variability between mechanisms are expected to account for why some older adults exhibit conserved AV speech perception while others do not. Importantly, we will also examine the extent to which the conserved AV speech demonstrated by some older adults translates to better perceived speech communication ability in day-to-day settings, as measured by self-report assessments. Identifying the mechanisms important for the conservation of AV speech in older adults can elucidate new targets for intervention to help preserve or even restore the communicative abilities of older adults with sensory deficits.