A Case of Memory Reconstruction: Sharing Memories via Communication

Abstract

The brain actively interprets and re-interprets our personal narrative. Incoming information is reshaped based on prior experience during the encoding, and this update process proceeds through consolidation, retrieval, and reconsolidation. But how does the brain implement this constructive process? In this dissertation I studied reconstructive memory from two perspectives. First, I asked whether memory and construction have shared neural mechanisms. To address this question, I studied how memories of past events (in a movie) are transmitted to other individuals, who mentally construct the events through listening to an audio recording of a participant’s recall in fMRI scanner. I observed reliable similarities between the scene specific patterns of brain response during encoding, recall, and construction of the same real-life episodes in the DMN. These mutual patterns of representation, suggest that a mutual mechanism to perform different construction-related functions might be at work. In the second study, I used fMRI to track the neural representations of the memory update during naturalistic recall. Participants watched a movie and at the end of the movie were exposed to a dramatic “twist” that changed the interpretation of the previously encoded movie. Participants were then instructed to recall several scenes in the movie in their own words (in the scanner). Most participants updated their recall to incorporate the twist. Two control groups performed similar tasks: one group watched a “spoiled” version of the movie (knowing the twist from the beginning), and a second group never saw the twist. Both control groups performed the spoken recall task in the scanner as well. This enabled us to compare how the twist transformed neural patterns during encoding and during recall. Our results demonstrated that providing participants with information about the twist beforehand (spoiled condition) altered the neural response patterns during the encoding phase (movie-viewing). Moreover, providing participants with information about the twist after the end of the encoding phase (post-viewing) transformed the neural patterns of the encoded information during recall. The similarity between activation patterns during encoding and recall was attenuated in participants who better updated their recall to accommodate the new information. This suggests that event representations are updated to retroactively accommodate new narrative information. Overall, the work presented in this dissertation provides a window into the neural mechanisms underlying social and constructive memory processes.