Figure 5. Offline ensemble reactivation drives retrospective memory-linking across days.

After single experiences, the cells active during learning are reactivated to support their consolidation. After a strong aversive experience, memories are linked retrospectively across days by the co-reactivation of the ensembles representing both the recent and the past neutral memory ensembles. During recall of the neutral memory, many of the cells that were active during both the neutral and aversive experiences are reactivated to drive fear in the neutral context.