title: Brain-behavior relationships in aging
title: episodic memory, medial-frontal parietal network, and cognitive reserve
titleType: Subtitle
Creators: name: Rivera-Dompenciel, Adriana M.
Publisher: name: University of Iowa
Year: 2025
Subjects: Cognitive Reserve
Episodic Memory
Functional Connectivity
Hippocampus
Medial-Frontal Parietal Network
public abstract
Aging

description: Normal aging entails cognitive and functional decline that could potentially become pathological unless certain lifestyle factors that contribute to protective cognitive effects manage to offset this course. Episodic memory (EM) is a cognitive function that is unmistakably impacted by age-related neurodegeneration, such that the amount of deterioration in EM can even distinguish between normal decline and that caused by Alzheimer’s Disease. EM also critically depends on the hippocampus (HC), a brain structure that is strongly associated with the Medial-Frontal Parietal Network (MFPN). The MFPN is a functional brain network associated with EM processes and undergoes structural and functional reorganization in normal and pathological aging. Both the HC and the MFPN are functionally subdivided in ways that may display heterogeneous aging processes, yet these are not well characterized in older adults in relation to the decline in their EM performance. In the same vein, it is unknown whether and how protective “cognitive reserve” (CR) lifestyle factors buffer the effects of EM decline via the MFPN and its interactions with the HC. For my research, I sought to characterize the HC-MFPN brain-behavior relationship with EM in aging. By determining the assignments of the three HC segments (Head, Body, and Tail) to either of the three MFPN subnetworks (A, B, and C), I prepared a functional brain atlas that served as the basis for processing resting state functional connectivity (rs-fc) data of two independent datasets of older adults to assess the brain-behavior relationship with EM. I further tested this relationship by looking at possible moderator effects from years of education and physical activity as part of a CR framework. I performed hierarchical multiple regressions per subnetwork for each dataset, including exploratory analyses evaluating other CR factors. Regarding my functional atlas, all three hippocampal segments were only significantly affiliated with the MFPN-C (which includes the Medial-Temporal Lobe), thus supporting the MFPN-C’s designation as a “medial-temporal subnetwork”. For the brain-behavior relationship, only MFPN-C rs-fc was related to the Late Learning EM measure of the Auditory-Verbal Learning Test (AVLT) when the exploratory CR factor of verbal intelligence was in the model. MFPN-A rs-fc was marginally significantly related, but no other predictor survived corrections for multiple comparisons in any other model. Overall, my notable results can be summed up by the following two points: (1) all HC segments showed a connection “preference” for MFPN-C, and (2) MFPN-C and less so MFPN-A rs-fc were related to EM performance only when accounting for verbal intelligence. Though some outcomes were unexpected—such as a lack of significant findings concerning performance in the commonly used AVLT Delayed Recall measure—they add to our understanding of the complex and still under-explored nature of rs-fc subnetworks, EM performance, and CR in aging.