Behavioral and Neural Correlates of Episodic Memory Regulation

Abstract

Episodic memory retrieval, while critical for daily living, needs to be regulated to maintain goal-directed behavior. Past work has shown that episodic memory regulation engages brain regions involved in cognitive control, such as the dorsolateral and ventrolateral prefrontal cortex. These regions interact with the medial temporal lobe structures to control retrieval processes. In the current study, I paired eye-tracking, a sensitive index of memory, with fMRI in a novel paradigm to address several open questions in the field of episodic memory regulation. Participants initially encoded three celebrity faces and three tools with multiple indoor and outdoor scenes. In a subsequent retrieval and search phase, participants were presented with scene cues and were instructed to either retrieve the associate of the scene, suppress it, or substitute it with one of the other encoded objects. After a delay, a search display consisting of the six encoded objects, intermixed with six dots was presented, and participants completed a simple visual search task with the dots. Incidental viewing directed to the associate of the scene cue was used as a measure of the success of episodic memory regulation. Results revealed that the two strategies of memory regulation tested here – retrieval suppression and thought substitution – led to a decrement in memory performance for pairs in which the associate was a tool. Memory regulation was also linked with reduced viewing of the associate embedded in the search display. Further, retrieval suppression and thought substitution activated distinct brain regions suggesting that although the two strategies have similar behavioral consequences, they are associated with distinct task demands. Finally, memory regulation affected the neural representation of retrieved memories in the hippocampus. However, the precise direction of this effect was different for faces and tools. Overall, the study yielded novel insights into the precise behavioral and neural substrates involved in two strategies of episodic memory regulation, and the effect of these processes on the representation of retrieved memories in the hippocampus.