Neural correlates of item and spatial context memory in high vs. lower-performance groups

情节记忆指的是我们在丰富的背景细节中编码和回忆过去经历的能力。健康的衰老通常与间歇性记忆力下降有关。然而，与健康的年轻人(18-35岁)相比，并不是所有健康的老年人(60-75岁)都表现出记忆力下降。此外，YA和OA在特定情景记忆任务，即空间语境记忆任务上的表现存在显著差异。基于这些观察，我目前的研究计划的目标是确定YA中成功的空间语境编码和提取的神经相关因素，并确定在记忆任务中表现在高四分位数的YA和OA与表现较差的YA和OA的区别的神经/认知策略。我有兴趣确定高表现的OA(High-OA)是不是那些：i)表现出与高YA(High-YA)相似的结构完整性和脑行为关联模式，从而比表现较低的OA(低OA)更好地维持认知功能(成功衰老的维持假说)；或者ii)表现出与高YA和低OA不同的大脑行为关联模式，这与更好的记忆表现相关(成功衰老的补偿假说)。我将进行两项功能磁共振研究，一项在YA(研究1)，另一项在OA(研究2)。我将让高、中、低表现的YA和OA参与一项空间背景记忆任务，同时在编码和检索阶段接受fMRI扫描。本研究旨在区分物品/熟悉度提取和空间记忆。在研究1中，我将检验关于不同的内侧颞区、顶区和额区在YA的情景编码和提取中的作用的具体假设。我将使用区域大脑活动、大脑变异性和区域间连通性的比较测量来推进我们关于人类情节记忆和大脑功能的模型。在研究2中，我将在年龄组内和年龄组之间比较三个表现组，以促进我们对大脑功能与年龄相关的表现差异的理解。我将测试是否与维持假设一致：高、中、低绩效队列显示出不同的大脑活动、连通性、变异性和大脑行为关联模式，这些差异是否与年龄组没有交互作用。我还将测试上述补偿假设。影响：我们的结果将推进我们大脑中的学习和记忆模型，并告诉我们成功的衰老是否与大脑维护和/或招募独特的补偿机制有关。因此，这项工作可能识别潜在的神经认知过程，这些过程可以被用来开发新的人类记忆优化训练方法/工具，并为人类记忆的神经计算模型提供信息。

Episodic memory refers to our ability to encode and retrieve past experiences in rich context detail. Healthy aging is generally associated with episodic memory decline. Yet, not all healthy older adults (OA; 60-75 yrs old) exhibit memory decline compared to healthy young adults (YA; 18-35yrs old). Moreover, there is significant variability in how YA and OA perform on specific episodic memory tasks, i.e. spatial context memory tasks. Based on these observations, the goals of my current research program are to identify the neural correlates of successful spatial context encoding and retrieval in YA, and determine the neuro/cognitive strategies that differentiate YA and OA who perform in the upper quartile on memory tasks (high-performers) from lower performing YA and OA. I am interested in determining if high-performing OA (High-OA) are those who: i) exhibit similar patterns of structural integrity and brain-behavior associations as high-performing YA (High-YA), and are thus maintaining' cognitive function better than their lower performing OA (Low-OA)(Maintenance Hypothesis of successful aging); or ii) exhibit different patterns of brain-behavioral associations to high-YA and low-OA, which correlate with better memory performance (Compensation Hypothesis of successful aging). I will conduct two fMRI studies, one in YA (Study 1) and one in OA (Study 2). I will have high-, moderate- and low-performing YA and OA participate in a spatial context memory task while undergoing fMRI scans during encoding and retrieval phases. This task is designed to differentiate item/familiarity retrieval from spatial recollection. In Study 1, I will test specific hypotheses about the roles of distinct medial temporal, parietal and frontal regions in episodic encoding and retrieval in YA. I will use comparative measures of regional brain activity, brain variability and inter-regional connectivity to advance our models of human episodic memory and brain function. In Study 2, I will compare the three performance groups, within and between age-groups, to advance our understanding of performance vs. age-related differences in brain function. I will test if, consistent with the Maintenance Hypothesis: High, Moderate and Low performance cohorts exhibit different patterns of brain activity, connectivity, variability and brain-behavior associations, and that these differences do not interact with age-group. I will also test the aforementioned Compensation Hypothesis.Impact: Our results will advance our models of learning & memory in the brain and inform us if successful aging is related to brain maintenance and/or the recruitment of unique compensatory mechanisms. Thus, this work may identify potential neurocognitive processes that can be leveraged to develop new training methods/tools for memory optimization in humans and inform neuro-computational model of human memory.