Age, Hearing Loss, and Sentence Comprehension: Neural Correlates

描述（由申请人提供）：成人老龄化代表着衰退和补偿的平衡。这项资助研究了成年人衰老、与年龄相关的听力下降和理解口语能力的神经网络的参与之间的相互作用。在理解行为层面的这种平衡方面已经取得了很好的进展，但对携带这些影响的潜在神经基质知之甚少。在这项研究中，我们研究了听觉句子理解的神经基础，以及听觉句子理解如何受到听觉敏度下降引起的感知努力和中枢认知负荷（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）的影响。我们在一个新的句子处理模型的指导下，该模型涉及几个可分离的神经基质，这些基质根据被处理材料的认知和知觉需求而参与。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来测试我们的神经认知模型，该方法将fMRI BOLD激活研究与灰质厚度和白质投影的结构成像结合起来，整合皮层区域。我们假设，这种选择性工作记忆和句子加工决策模型在衰老过程中部分失效，是因为大脑区域之间的白质投射有限，以及背外侧前额皮质皮质变薄。我们还评估了潜在的补偿机制。目的1研究句法复杂性和语速的影响，目的2研究工作记忆负荷对句子的影响，目的3研究解决句子加工过程中遇到的词汇和句法歧义所需的决策。我们提出的研究将填补认知老化和年龄相关性听力损失对老年人日常言语理解的相互作用方面的一个关键空白。这项工作也可以作为早期检测病理变化的框架，因为它影响了老化的大脑中的语言理解。

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.