Beyond Temporary Scaffolding: Persistent Hippocampal Engagement and Brain-Wide Network Reorganization in Remote Memory Consolidation

Abstract

The standard model of memory consolidation posits a temporary role for the hippocampus. We challenge this view by combining a novel face-name associative memory task with cross-modal decoding of fMRI data. We demonstrate that the hippocampus remains persistently engaged in representing both recent and remote memories, with distinct subregional contributions: recent memories were represented in the right posterior hippocampus, whereas remote memories additionally recruited the left anterior hippocampus. This sustained hippocampal involvement occurred alongside a large-scale network reorganization. Remote memory retrieval was accompanied by increased global connectivity among semantic regions, yet the hippocampus itself did not emerge as a major hub. Instead, network hubs shifted from the medial prefrontal cortex (mPFC) for recent memories to the mPFC and bilateral inferior parietal lobule for remote memories. These findings reveal a dynamic process in which the hippocampus preserves long-lasting representational functions while the broader memory network undergoes extensive reorganization.