Every day, our brain captures impressions, experiences, and moments. But only a few turn into lasting memories that stay with us for years or even a lifetime. So, what decides which ones stick?
A new study in Nature shows that long-term memory forms through a series of molecular timers that activate in different parts of the brain. Scientists used a complex virtual reality system with mice to control how intense and repeated experiences were. They watched how the brain chooses certain memories for long-term storage while letting others fade away.
We used to think the hippocampus stored short-term memories and the cortex handled long-term ones like a ‘switch.’ But the new findings reveal a much more complicated picture. In 2023, researchers found that the thalamus serves as a main gateway, deciding which memories go to the cortex for long-term storage.
The study uncovered three genetic programs—Camta1, Tcf4, and Ash1l—that are key to this process. Each one activates at different times: some fade quickly for fast forgetting, while others work slowly but ‘lock’ memories in for a long time. Using CRISPR, they showed that turning off these molecules shortens memory duration.
This discovery about how the brain uses ‘layers’ of memory and sequential molecular regulators opens new ways to understand conditions like Alzheimer’s. In the future, we might be able to transfer memories through parallel neural circuits, avoiding damaged areas.
