Neuroimaging of Age-Related Changes in Language

描述（由申请人提供）：成人发育通常与身体和认知能力下降的概念有关。然而，与词义相关的语义过程在很大程度上被保留了下来：例如，随着年龄的增长，词汇量会增加，语义词联想和类别成员判断也会被保留下来。不仅语义记忆通常在健康的老龄化过程中保持不变，而且词汇项目之间的关联数量也可能增加。此外，尽管年龄相关的变化会影响大脑结构，但这些能力仍然保持不变。尽管保存的语义过程中的语音过程的具体赤字已被观察到。例如，老年人在命名物体时表现出速度和准确性下降，口误增加。年龄对语义和语音过程的影响模式表明，这两种能力的认知组织存在根本差异。传递缺陷理论通过提出语义和语音系统的认知结构的根本差异，为这些结果的不对称模式提供了一种理论解释。拟议的研究测试对比预测的传输缺陷理论和其他理论的年龄差异的语义和语音过程。这项建议的首要目标是使用行为的措施，扩散张量成像（DTI），和功能磁共振成像（fMRI），调查的机制不对称的老化影响的语音和语义过程。虽然这种不对称性已被调查的行为，很少有研究调查与这些认知变化相关的年龄相关的神经变化。这些结合的方法将把潜在的结构变化与功能激活和行为表现联系起来。拟议的实验将表征语义和语音过程中的大脑老化，调查任务无关的信息在语言产生和语言理解任务的作用，并调查与年龄相关的变化，在短暂的和持续的语义和语音过程。这项研究将提高目前对语言中与年龄相关的变化的科学理解，并描述导致认知能力下降的神经因素。这些数据将特别与可塑性的概念有关，可塑性是老年人行为功能维持的基础。这些结果将为区分正常的年龄相关的语言变化与疾病的影响提供必要的信息，在我们对语言年龄相关变化的理论概念化方面取得进展，并为健康老龄化和临床患者的认知衰退的康复治疗提供见解。 公共卫生相关性：公共卫生将受益于拟议的研究，通过提高我们的神经和行为基础的语言与年龄相关的变化的基本知识。这项研究将有助于我们区分健康老龄化与临床状况的能力，并为认知衰退的康复治疗提供见解。

DESCRIPTION (provided by applicant): Adult development is often associated with the concept of physical and cognitive decline. However, semantic processes related to the meaning of words are largely preserved: vocabulary increases as we age, and semantic word associations and category membership judgments are preserved, for example. Not only does semantic memory typically remain intact during healthy aging, but the number of associations among lexical items may also increase. In addition, these abilities are maintained despite age-related changes that affect brain structure. Despite the preservation of semantic processes specific deficits in phonological processes have been observed. For example, older adults exhibit decreased speed and accuracy in naming objects and increased slips of the tongue. This pattern of aging effects on semantic and phonological processes suggests a fundamental difference in the cognitive organization of these two abilities. The Transmission Deficit Theory provides one theoretical account of these asymmetric patterns of results by proposing fundamental differences in the cognitive architecture of the semantic and phonological systems. The proposed research tests contrasting predictions of the Transmission Deficit theory and other theories for age differences in semantic and phonological processes. The overarching goal of this proposal is to use behavioral measures, diffusion tensor imaging (DTI), and functional magnetic resonance imaging (fMRI) to investigate the mechanisms underlying the asymmetry in aging effects on phonological and semantic processes. While this asymmetry has been investigated behaviorally, few studies have investigated the age-related neural changes that are related to these cognitive changes. These combined methodologies will relate the underlying structural changes to functional activation and behavioral performance. The proposed experiments will characterize semantic and phonological processes in the aging brain, investigate the role of task-irrelevant information in language production and language comprehension tasks, and investigate age-related changes in transient and sustained semantic and phonological processes. This research will improve the current scientific understanding of age-related changes in language, and describe the neural factors that contribute to cognitive decline. The data will be particularly relevant to the concept of plasticity that underlies the maintenance of behavioral functions in older adults. These results will provide essential information for differentiating normal age-related changes in language from the effects of disease, forge advances in our theoretical conceptualization of age-related change in language, and provide insight into rehabilitative therapies for cognitive decline in both healthy aging and clinical patients. PUBLIC HEALTH RELEVANCE: Public health will benefit from the proposed research by improving our basic knowledge of the neural and behavioral foundations of age-related change in language. This research will facilitate our ability to differentiate healthy aging from clinical conditions, and provide insight into rehabilitative therapies for cognitive decline.