Relationship Between Neural Correlates of Episodic Memory,Age, Memory Performanc

描述(由申请人提供)：情节记忆随着年龄的增长显著下降，与大多数其他形式的记忆相比，不成比例地下降，而情节记忆的严重损害是几个与年龄相关的神经退行性疾病的显著特征。了解健康受试者与年龄相关的间歇性衰退的认知和神经基础是很重要的，因为即使是进入70岁高龄的健康人典型的相对轻微的损伤，也足以对认知功能产生有害影响。因此，开发干预措施来改善与年龄相关的记忆衰退将具有相当大的价值，而且对其原因的更多了解将大大促进这一点。同样重要的是，如果不知道记忆及其神经底物在健康衰老过程中的变化，就很难全面了解阿尔茨海默病等病理疾病所特有的更严重的记忆损害。本研究计划的主要目的是阐明支持情景记忆的认知过程的神经关联中与年龄相关的差异的功能意义，确定这些差异中的哪些反映了与年龄相关的记忆功能下降的过程，哪些反映了改善这种下降的补偿机制。该程序的重点是情节编码和提取的神经关联，通过功能磁共振成像的“后续记忆”和“提取成功”效应来索引。研究发现，相对于20岁的S，60岁的S和70岁的S在后续记忆和提取成功效应的大小和皮质分布上表现出特征差异。其中一个差异是“右额叶过度招募”--相对于年轻个体而言，年龄较大的人在右侧前额叶皮质的后续记忆效应更大。最近的发现表明，右额叶对后续记忆效应的过度招募与相对较差的记忆表现水平有关。将进行五个实验，共同严格表征情景编码和提取的神经关联与年龄、记忆表现以及包括白质完整性在内的各种大脑结构指标之间的关系。这些研究包括对年轻人、中年人和老年人编码和提取相关神经活动的大规模调查，允许调查编码和提取效果与年龄相关记忆下降之间的关系的纵向研究，调查老年人后续记忆效应如何随着学习任务的难度而变化的研究，以及旨在验证以下假设的实验：在成功的情景提取过程中引发的神经活动在老年人中携带的区分较少的信息在年轻人中。

DESCRIPTION (provided by applicant): Episodic memory declines substantially and, relative to most other forms of memory, disproportionately, with age, while a considerably more severe impairment of episodic memory is a prominent feature of several age-related neurodegenerative disorders. An understanding of the cognitive and neural bases of age-related episodic decline in healthy subjects is important because even the relatively modest impairment typical of healthy individuals entering their 70's is sufficient to have a detrimental impact on cognitive function. Thus, the development of interventions that ameliorate age-related memory decline would be of considerable value and would be much facilitated by increased understanding of its causes. Equally important, a full understanding of the more severe memory impairments characteristic of pathological conditions such as Alzheimer's Disease will be difficult to achieve without knowledge of how memory and its neural substrates change in the course of healthy aging. The overarching aim of the present research program is to elucidate the functional significance of age- related differences in the neural correlates of cognitive processes supporting episodic memory, determining which of these differences reflect processes that contribute to age-related decline in memory function, and which reflect compensatory mechanisms that ameliorate such decline. The focus of the program is on the neural correlates of episodic encoding and retrieval as indexed by fMRI 'subsequent memory' and 'retrieval success' effects. The program takes as its starting point findings indicating that, relative to individuals in their 20's, people in the 60's and 70's demonstrate characteristic differences in the magnitude and cortical distribution of subsequent memory and retrieval success effects. One of these differences takes the form of 'right frontal over-recruitment' - larger subsequent memory effects in the right prefrontal cortex in older relative to younger individuals. Recent findings indicate that right frontal over-recruitment of subsequent memory effects is associated with relatively poor levels of memory performance. Five experiments will be conducted that, together, will rigorously characterize the relationship between neural correlates of episodic encoding and retrieval and age, memory performance, and a variety of structural brain measures including white matter integrity. The studies include a large-scale investigation of encoding- and retrieval-related neural activity in young, middle-aged and older individuals, a longitudinal study permitting investigation of the relationship between encoding and retrieval effects and age-related memory decline, a study to investigate how subsequent memory effects vary with the difficulty of the study task in older people, and an experiment aimed at testing the hypothesis that the neural activity elicited during successful episodic retrieval carries less well- differentiated information in older than in young individuals.