The consolidation of new but not reactivated memory requires hippocampal C/EBPβ

Long-term memory formation consists of multiple phases. A new memory is initially labile and sensitive to disruption by a variety of interfering events or agents. To become stable, this new memory undergoes a process known as consolidation, which, in the case of declarative memories, occurs within the medial temporal lobes and requires gene expression. When recalled, memories re-enter a new phase of vulnerability and seem to require a reconsolidation process in order to be maintained. Here we show that consolidation but not reconsolidation of inhibitory avoidance memory requires the expression of the transcription factor CCAAT enhancer binding protein β (C/EBPβ) in the hippocampus. Furthermore, in the same region, de novo protein synthesis is not essential for memory reconsolidation. C/EBPβ is an evolutionarily conserved genetic marker that has a selective role in the consolidation of new but not reactivated memories in the hippocampus.