Memory consolidation requires the sequential activation of temporally-specific epigenetic changes in the hippocampus and the cortex of the brain, reports a paper in Nature Communications this week. These findings shed new light on the role of epigenetic modifications in the formation of memories.

Memory consolidation is known to depend on two major brain regions, the hippocampus and the cortex. While the hippocampus is recruited for the formation and short-term storage of new memory traces, the cortex, in particular the prefrontal cortex, is required for long-term storage. Although epigenetic processes are thought to be associated with memory formation, the precise dynamics of these processes remain poorly understood.

vIsabelle Mansuy and colleagues train mice with an object recognition task and examine the epigenetic changes in the brain. They find that epigenetic modifications are rapidly activated in the hippocampus after learning, but are activated after a temporal delay in the cortex.

The authors conclude that these specific modifications can be conceived as molecular mnemonics which are crucial for sustaining the transfer of information between the hippocampus and the cortex and therefore the consolidation of memories.