Age, Hearing Loss, and Sentence Comprehension: Neural Correlates

描述(申请人提供)：成年人的衰老代表着衰退和补偿的平衡。这项拨款调查了成年人年龄增长、与年龄相关的听力下降以及理解口语的能力所依赖的神经网络的参与所产生的交互影响。在行为层面上对这种平衡的理解已经取得了很好的进展，但对承载这些影响的潜在神经底物的了解要少得多。在这项授权中，我们讨论了听觉句子理解的神经基础，以及由于听力敏锐度降低而产生的知觉努力，以及中央认知负荷(如句法复杂性、语速、工作记忆需求以及日常话语中出现的语义和句法歧义)如何影响听力句子理解。我们遵循一种新的句子处理模型，该模型涉及几个可分离的神经底物，这些底物根据被处理材料的认知和知觉需求而投入使用。我们的受试者将是健康的年轻人和老年人，具有良好的听力敏锐度和轻度至中度听力损失。我们使用新的成像方法测试我们的神经认知模型，这些方法将fMRI大胆的激活研究与灰质厚度的结构成像和整合皮质区域的白质投影相结合。我们假设，在句子处理过程中，这种选择性工作记忆和决策的模型在衰老过程中部分崩溃，这是因为大脑区域之间的白质投射有限，以及前额叶背外侧皮质变薄。我们还评估了潜在的补偿机制。目标1考察句法复杂性和语速的影响，目标2具体操作句子中的工作记忆负荷，目标3考察解决句子处理过程中遇到的词汇和句法歧义所需的决策。这项拟议的研究将填补我们在认知老化和年龄相关听力损失对老年人日常言语理解的交互影响方面的一个关键知识空白。这项工作还可以作为早期发现病变的框架，因为它会影响老化大脑的语言理解。) 公共卫生相关性：成人老龄化代表着衰退和补偿的平衡，这项拨款调查了成人老龄化、与年龄相关的听力损失以及听和理解口语时神经补偿模式的交互影响。从句子处理的一种新的神经认知模型的角度，我们用创新的成像方法测试了我们的方法，这些方法结合了fMRI大胆激活研究、灰质厚度的结构成像和白质投影，这些区域整合了听语音时激活的大脑区域。这些研究将填补我们在认知老化和年龄相关听力损失对老年人日常言语理解的相互影响方面的知识空白，并可能作为早期发现病理变化的框架，因为它影响老化大脑的语言理解。

DESCRIPTION (provided by applicant): Adult aging represents a balance of decline and compensation. This grant investigates the interacting effects of adult aging, age-related declines in hearing acuity, and engagement of the neural networks that underlie the ability to comprehend spoken sentences. Good progress has been made in understanding this balance at the behavioral level, but far less is known about the underlying neural substrates that carry these effects. In this grant we address the neural basis for aural sentence comprehension and how this is affected by perceptual effort due to reduced hearing acuity, and central cognitive loads such as those imposed by syntactic complexity, speech rate, working memory demands, and the semantic and syntactic ambiguities that occur in everyday discourse. We are guided by a novel model of sentence processing that implicates several dissociable neural substrates that become engaged depending on the cognitive and perceptual demands of the materials being processed. Our subjects will be healthy young and older adults with good hearing acuity and with mild-to-moderate hearing loss. We test our neurocognitive model using novel imaging methods that combine fMRI BOLD activation studies with structural imaging of gray matter thickness and white matter projections that integrate cortical areas. We hypothesize that this model of selective working memory and decision-making during sentence processing partially breaks down during aging because of limited white matter projections between brain regions, and cortical thinning in dorsolateral prefrontal cortex. We also assess potential compensatory mechanisms. Aim 1 examines effects of syntactic complexity and speech rate, Aim 2 specifically manipulates working memory load within sentences, and Aim 3 investigates decision-making needed to resolve lexical and syntactic ambiguities encountered during sentence processing. The proposed studies will close a critical gap in our knowledge of the interacting effects of cognitive aging and age-related hearing loss on everyday speech comprehension in older adults. This work may also serve as a framework for early detection of pathological change as it affects language comprehension in the aging brain.) ) PUBLIC HEALTH RELEVANCE: Adult aging represents a balance of decline and compensation, and this grant investigates the interacting effects of adult aging, age-related hearing loss, and patterns of neural compensation while listening to and understanding spoken sentences. Using the perspective of a novel neurocognitive model of sentence processing, we test our approach with innovative imaging methods that combine fMRI BOLD activation studies with structural imaging of gray matter thickness and white matter projections that integrate brain areas activated while listening to speech. These studies will close a critical gap in our knowledge of the interacting effects of cognitive aging and age-related hearing loss on everyday speech comprehension in older adults, and may also serve as a framework for early detection of pathological change as it affects language comprehension in the aging brain.