Differential Reactivation of Task-Demand-Associated Firing Patterns in Subicular and CA1 Place Cells during a Hippocampal Memory Task

Reactivation of place cells during sharp-wave ripples (SWRs) in the hippocampus is pivotal for memory consolidation, yet the SWR dynamics between the hippocampus and its neighboring subiculum remain underexplored. This study examined the differential SWR-associated reactivations of task-demand-associated representations in the subiculum and CA1 during a visual scene memory task in rats. In the task, the spiking activities of place-cell ensembles were reactivated during a SWR event according to task demands. These reactivations were more frequent and associated with more heterogeneous task-demand types in the subiculum compared to CA1. These subicular characteristics were driven by multiple subfields within the subicular place field, parcellated by the theta phase precession cycle. In contrast, CA1 exhibited a higher incidence of spatial replay than the subiculum. These findings indicate that the subiculum plays a key role in transmitting task-specific variables from the hippocampus to other brain regions.