Systems-level reconsolidation: reengagement of the hippocampus with memory reactivation.

Certain types of memories are dependent on the hippocampus for a short period of time following training, after which they are no longer susceptible to hippocampal manipulations. Having completed this initial consolidation process, a memory may once again engage the hippocampus (undergo reconsolidation) when recalled. Two studies in the current issue of Neuron make important advances in our understanding of reconsolidation but reach different conclusions about the modifiability of old memories.