Hippocampal-cortical networks predict conceptual versus perceptually guided narrative memory

Current theories of event memory propose distinct connections between the hippocampus and neocortical regions, particularly those within the default mode network (DMN) subsystems, to support processing different types of content in memory. It has been established that hippocampal connectivity supports integrating this disparate content into unified event memories, suggesting that changing the way that an event is described could change the underlying hippocampal neural network. To address this knowledge gap, we developed event narratives that described the same core story (e.g., grocery shopping) with identical central story details described with additional descriptive details that were conceptually or perceptually related to the story. Using fMRI, we established hippocampal connectivity patterns as a group of human participants (N=35, of any sex) encoded these narratives, and then related these patterns to later memory for the narrative details. Consistent with prior work, we found that the conceptual narratives were associated with stronger anterior hippocampal connectivity to regions within the core and dorsomedial DMN subsystems, and a portion of this connectivity pattern predicted memory for the core story of the narrative. The perceptual narratives were selectively associated with anterior hippocampal connectivity to parietal and lateral temporal regions and regions outside the standard DMN, in relation to memory performance. These results provide new insights into hippocampal and DMN functional organization and how distinct neural components contribute differently to event memory. Significance Statement The present manuscript presents evidence that describing the same event with different content details results in shifts in hippocampal connectivity to different brain networks. Additionally, these content-based shifts in hippocampal connectivity patterns can predict later memory for the same elements of an encoded event.