Asymmetry Reduction with Aging : fMRI Studies of Memory

说明(由申请人提供)拟议研究的主要目标是 使用功能磁共振成像(FMRI)来阐明 衰老对认知相关神经的影响。特别是，我们将调查 脑的发现的概括性和功能意义 认知表现过程中的活动倾向于较少偏侧化 老年人的左半球和右半球多于年轻人。 研究与年龄相关的不对称性减少的概括性 认知任务，我们将比较衰老对大脑活动的影响 情景记忆编码、情景记忆检索、语义记忆检索 和工作记忆。探讨年龄相关因素的概括性 成年人口的不对称性减少，我们将调查 认知表现、教育和额叶的个体差异 函数，并将考察一大组均匀分布在 从年轻到老年。研究与年龄相关的不对称性的概括性 整个大脑的减少，我们将使用 感兴趣区域(ROI)方法，并将计算侧化指数 对于每个ROI。ROI分析将与体素分析相辅相成。 最后，探讨年龄相关不对称性的功能意义。 减少，我们将通过以下方式测试补偿和去分化假设 大脑活动与认知表现之间的关联，并通过使用 事件相关功能磁共振分析。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 有益于认知能力的功能。根据 去分化假说，它反映了与年龄相关的参与困难 专门的神经机制。在这些假设之间做出决定具有重要意义 具有实际意义。例如，如果与年龄相关的不对称性减少 反映一种补偿机制，双半球参与可能是有针对性的 作为认知康复计划的一个目标。建议的研究计划 对促进健康有直接影响。了解神经 正常大脑中认知功能的基础是任何 治疗或康复脑源性认知功能障碍的理性尝试 此外，功能障碍，理解与年龄相关的认知的神经基础 赤字最终将使药物和康复的发展成为可能 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.