Co-allocation of distinct contextual memories within a wide time window temporal dynamics and neuronal co-reactivation during retrieval

Abstract

Recent studies have shown that a shared neuronal ensemble in the hippocampus links distinct contextual memories encoded within a certain time window (specifically, 5 hours, 2 and 7 days). Here we explored the temporal dynamics of two contextual (neutral and aversive) memories linking and analysed neuronal ensembles in the hippocampus, amygdala and different cortical regions reactivated during retrieval. Firstly, we have found that memories integrated across different time-points including several hours, days and weeks but not if learning phases was separated by short-term and very long-term time intervals. Secondly, we have demonstrated a higher neuronal co-reactivation in the hippocampus and amygdala during retrieval in case of memories integration that supports the hypothesis that shared neuronal ensembles link distinct memories. Finally, we have elicited that proportions of reactivated neuronal ensembles in these brain regions are greater in case of contextual memories integration.