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

项目摘要 老年人比年轻人更难识别听觉（AO）和视觉（VO）语音。尽管 由于这些单一感觉的缺陷，一些老年人可以像年轻人一样准确地识别视听（AV）语音 成年人了老年人被发现表现出更多的跨模态可塑性，多感觉整合， 额叶皮层对感觉输入的调节，但这些与年龄有关的变化在多大程度上是有益的 并解释老年人保守的AV语言是一个关键的知识差距。建议的目标 研究计划将使用一种创新的神经系统方法，包括电生理学（EEG）， 结构成像（sMRI）和扩散成像（DKI），以表征特定的神经机制， 适应年龄以支持AV语音。将使用结合EEG和sMRI的源约束分析 计算特定感兴趣区域中产生的电势以及区域之间的功能连接 感兴趣跨模态可塑性将通过跨感觉反应幅度（视觉诱发的）来表征。 听觉皮层中产生的诱发电位和视觉皮层中产生的诱发电位）， 听觉和视觉皮层之间的功能连接（目标1）。多感官整合将是 其特征在于在颞顶皮层产生的AV反应幅度和功能连接 颞顶皮层和感觉皮层之间的联系（目标2）。感觉输入的额叶皮层调制 其特征在于在额叶皮层下部产生的言语诱发电位和功能性 下额叶皮层和感觉皮层之间以及下额叶皮层和 颞顶皮质（Aim 3）。我们假设，年龄相关的单感官缺陷的负面影响 AV言语感知将通过更大程度地依赖跨通道可塑性（目标1）、多感觉 整合（目标2）和/或感觉输入的额叶皮层调制（目标3）。虽然功能连接 假设是为了促进这些机制中的每一个，并保存老年人的AV语言，年龄- 预期相关的白色物质降解（DKI）会限制功能连接，使得任何年龄相关的 功能性连接的增加可能受到与年龄相关的白色脑片完整性缺陷的影响。虽然我们 假设每种机制都可以部分解释一些老年人保守的AV语音， 成年人，个体差异和机制之间的可变性预计将解释为什么一些老年人 成年人表现出保守的AV言语感知，而其他人则没有。重要的是，我们还将研究 在某种程度上，一些老年人所表现出的保守的AV语音转化为更好的感知 日常环境中的言语沟通能力，通过自我报告评估进行测量。识别 对老年人AV言语保护重要的机制可以阐明新的靶点， 干预，以帮助保存甚至恢复与感官缺陷的老年人的沟通能力。

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.