The brain actively erases long-term memories!

It’s not always our fault when we forget something

We blame ourselves all the time for forgetting things, and sometimes, to be fair, it is our fault. Perhaps we didn’t pay close attention in the first place, or maybe we didn’t take care to review that new information at least a few times to make sure it became more of a long-term memory. But research has revealed that the brain actually has a deletion process that erases memories bit by bit, and one which we, apparently, have no control over.

the human brainThe researchers in a team led by the University of Edinburgh are hopeful that this discovery could point us towards new ways to combat dementia. Their finding are published in The Journal of Neuroscience. The discovery could also explain why some long-term memories are so persistent, as in PTSD (post-traumatic stress disorder). 

Memories are maintained in the brain by a process of chemical signalling between neurones, and this process depends on certain specialised receptors called AMPA receptors. The more AMPA receptors that have been built up on the surface where neurones connect, the stronger the memory (and presumably the number of these receptors increases as we regularly review information we want to store in memory).

The brain starts deleting memories, bit by bit

The research team found that the memory deletion process happens when neurones remove AMPA receptors from the point at which they connect. Gradually, if the memory is not recalled, the number of AMPA receptors may reduce, with the effect that the memory is slowly erased, bit by bit (it is not yet known why brain cells start to remove AMPA receptors, and why only on certain cells).

This shows the importance of recalling and reviewing memories you want to keep stored in your brain. It’s not enough to learn something – you have to review that information from time to time. And a good way to do it is to do it is in an ordered or organised way, such as keeping a list of those things you want to store long-term and reviewing them briefly once a week or so.

The research also indicated that this process of actively erasing memories actually helps animals to adapt their behaviour according to their surroundings.

Can drugs stop the brain forgetting?

Researchers also found that blocking the removal of AMPA receptors with a drug that kept them at the surface of the cell did indeed stop the natural forgetting (or erasing) of memories. Tests are ongoing to investigate potential therapies to prevent memory loss due to Alzheimer’s and other forms of dementia.

However, researchers are aware that this active ‘forgetting’ might actually be an important part of learning and memory. It’s worth noting, at this point, that we simply don’t have a very clear idea of how the brain learns new things and remembers them, so it would be a mistake to assume that we now have the keys to mastering memory. Using drugs to interfere with this memory deletion process, for example, could potentially affect the brain’s ability to absorb new information and retrieve existing memories.

Dr Oliver Hardt, of the Centre for Cognitive and Neural Systems at the University of Edinburgh, summed it up like this:

“Our study looks at the biological processes that happen in the brain when we forget something. The next step is to work out why some memories survive whilst others are erased. If we can understand how these memories are protected, it could one day lead to new therapies that stop or slow
pathological memory loss.”

Maybe we’re getting closer to actually understanding memory

I can only add that if we learn more about how and why certain memories are erased it might also mean we’re a step closer to having more control over the whole faculty of memory. It might prove to be a very small step, but bit by bit we seem to be learning how the whole thing works.

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