INVESTIGATING BEHAVIORAL AND NEURAL CORRELATES OF EPISODIC MEMORY IN EARLY CHILDHOOD

Abstract

Episodic memory is a cornerstone ability that allows us to draw on past experiences to guide future behavior. Rather than reflecting a unitary process, episodic memory is supported by multiple interacting components, including memory for items, relations, details, order of events, and personally relevant life events. However, how these components interact over development, how they relate to hippocampal maturation, and how methodological differences influence their measurement remain poorly understood. In this dissertation, I investigate the behavioral and neural correlates of episodic memory, with a focus on mnemonic discrimination, in early childhood. I demonstrate a hierarchical organization of the episodic memory components such that simpler components support development of more complex components. Moreover, I show a developmental shift from memory driving hippocampal development to memory and hippocampal development shaping each other. Next, using a novel, block-design, passive-viewing Mnemonic Similarity Task (MST) fMRI paradigm, I demonstrate activation patterns consistent with pattern separation in the medial temporal lobe of children while adults show patterns consistent with a recall-to-reject strategy. Next, I demonstrate mnemonic discrimination’s sensitivity to sleep-dependent memory consolidation as habitual nappers leveraged the afternoon sleep bout for generalization processes and overnight sleep to recover details. Finally, I show that performance on the MST varies due to administration format, how mnemonic discrimination is calculated, the number of testing sessions administered, and testing environment. These findings advance understanding of the factors that underly episodic memory development. Further, they highlight strategies for supporting its development in early childhood and improving the precision with which it is measured. Together, these findings provide a more comprehensive account of episodic memory development by integrating behavioral, neural, and contextual perspectives. This work highlights the importance of considering both hippocampal maturation and methodological factors when studying memory in early childhood.