Every day, your brain takes in new experiences, emotions, and ideas. Some of these become lasting memories, while others fade away.
But how does your brain decide what to keep and what to forget? A recent study by scientists at Rockefeller University provides new insights into this fascinating process. The findings were published in the journal Nature.
For a long time, scientists believed that memory worked like a simple switch. The hippocampus stored short-term memories, and the cortex stored long-term ones. Once a memory moved to the cortex, it was thought to last forever. But this model didn’t explain why some memories disappear after a few weeks while others stay with us for a lifetime.
Now, researchers have found that memory is much more dynamic. Instead of a one-time switch, memories go through a series of changes in different parts of the brain. These changes work like a system of timers, deciding how long a memory should last.
Using virtual reality, the team trained mice to remember different types of experiences. Some memories were repeated more often, making them seem more important. The scientists then looked at the mice’s brains to see what changed when a memory lasted longer.
They found that several areas of the brain—including the thalamus and the anterior cingulate cortex—play key roles in this process. The thalamus acts like a gatekeeper, helping decide which memories are important enough to store for the long term.
To dig deeper, the team used a genetic tool called CRISPR to turn off specific genes in these brain areas. They found that certain molecules were essential for keeping memories intact. These molecules didn’t help form the memory, but they were critical in making sure it stayed.
In the thalamus, two key molecules called Camta1 and Tcf4 helped protect the memory in its early stages. Camta1 helps keep the memory stable right after it forms, while Tcf4 works later to strengthen brain cell connections.
In the anterior cingulate cortex, a molecule called Ash1l helps with long-term memory by supporting changes in DNA structure that make memories more stable.
Together, these molecules act like a sequence of timers. Some activate quickly but fade fast, allowing short-term memories to disappear. Others activate more slowly and provide the support needed for long-term memory. The more often a memory is recalled or repeated, the more likely it is to move from short-term to long-term storage.
What’s interesting is that these memory molecules aren’t only found in the brain. Ash1l belongs to a family of proteins that help the immune system remember infections and help cells “remember” their identity during growth. This suggests that the brain may be using general biological memory tools to manage our thoughts and experiences.
These findings could have real-world benefits. In diseases like Alzheimer’s, parts of the brain that store memories get damaged.
If scientists can understand how memories move and which parts of the brain help preserve them, they might one day find ways to reroute memories around damaged areas. This could help people keep their memories even when parts of their brain are affected by disease.
The next step for the researchers is to learn more about what activates these memory timers and how the brain decides which memories are worth keeping. They believe the thalamus plays a central role in this decision-making process.
In the end, memory is not just about storing information. It’s a living, changing process involving multiple brain regions and a series of gene-based programs. Understanding how these memory timers work could open up new ways to treat memory loss and improve learning.
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