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

点击翻译按钮获取中文摘要

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.