Asymmetry Reduction with Aging : fMRI Studies of Memory

描述（由申请人提供）拟议研究的主要目标是 使用功能性磁共振成像（fMRI）来阐明 衰老对认知神经系统的影响特别是，我们将调查 大脑的普遍性和功能意义 在认知表现过程中的活动往往是不那么偏侧化之间的 老年人的左右半球比年轻人的要多。 为了研究年龄相关的不对称性减少的普遍性， 认知任务，我们将比较老化对大脑活动的影响， 情景记忆编码，情景记忆提取，语义记忆提取， 和工作记忆调查年龄相关的普遍性 在整个成年人群的不对称减少，我们将调查 认知表现、教育和额叶的个体差异 函数，并将检查均匀分布的大量受试者， 从年轻到年老。探讨年龄相关不对称性的普遍性 减少整个大脑，我们将分析大脑活动数据使用 感兴趣区域（ROI）方法，并将计算偏侧化指数 每一个王ROI分析将辅以体素分析。 最后，探讨年龄相关不对称的功能意义 减少，我们将测试补偿和去分化假说， 将大脑活动与认知表现联系起来， 事件相关fMRI分析。根据补偿假说， 与年龄相关的不对称性减少反映了与年龄相关的大脑重组 对认知能力有益的功能。根据 去分化假说，它反映了一个与年龄有关的参与困难， 专门的神经机制在这些假设之间做出决定， 实际影响。例如，如果年龄相关的不对称性减少 反映了一种补偿机制，双半球参与可能是针对 作为认知康复项目的目标。拟议的研究计划 对促进健康有直接的影响。了解神经 正常大脑中认知功能的基础是任何 治疗或恢复因脑损伤引起的认知缺陷的合理尝试 此外，了解与年龄相关的认知功能障碍的神经基础 赤字最终将允许药物和康复的发展 改善这些缺陷的方法。

DESCRIPTION (provided by applicant) The main goal of the proposed research is to use functional magnetic resonance imaging (fMRI) to elucidate the effects of aging on the neural correlates of cognition. In particular, we will investigate the generalizability and functional significance of the finding that brain activity during cognitive performance tends to be less lateralized between the left and right hemispheres in old adults than in young adults. To investigate the generalizability of age-related asymmetry reductions across cognitive tasks, we will compare the effects of aging on brain activity during episodic memory encoding, episodic memory retrieval, semantic memory retrieval, and working memory. To investigate the generalizability of age-related asymmetry reductions across the adult population, we will investigate individual differences in cognitive performance, education, and frontal-lobe function, and will examine a large group of subjects evenly distributed from young to old age. To investigate the generalizability of age-related asymmetry reductions across the brain, we will analyze brain activity data using a regions-of-interest (ROIs) approach, and will calculate a lateralization index for each ROI. ROI analyses will be complemented with voxel-wise analyses. Finally, to investigate the functional significance of age-related asymmetry reductions, we will test compensation and dedifferentiation hypotheses by correlating brain activity with cognitive performance and by using event-related fMRI analyses. According to the compensation hypothesis, age-related asymmetry reductions reflect an age-related reorganization of brain functions that is beneficial for cognitive performance. According to the dedifferentiation hypothesis, it reflects an age-related difficulty in engaging specialized neural mechanisms. Deciding between these hypotheses has important practical implications. For example, if age-related asymmetry reductions reflect a compensatory mechanism, bihemispheric involvement could be targeted as a goal of cognitive rehabilitation programs. The proposed research program has direct implications for the promotion of health. Understanding the neural basis of cognitive functions in the normal brain is a precondition for any rational attempt to cure or rehabilitate cognitive deficits due to brain dysfunction, Moreover, understanding the neural basis of age-related cognitive deficits will eventually allow the development of drugs and rehabilitation methods to ameliorate these deficits.