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Remember that memory story…

If you enjoyed reading my WSM story on memory, check out this article from Monday’s New York Times. It gets into one of the deepest questions about memory, which is, how and when does the brain select which memories to keep and which to discard? We take in far more information every day than we can remember, and since our brains are of finite size, they can’t retain a record of everything.

New York Times article on memoryThe memories with the greatest staying power, says WSU psychologist Jay Wright, are those that are important to us personally, especially those with a strong emotional element. Such memories seem to be engraved so deeply in our minds that we can vividly recall a moment that occurred decades ago, even if we haven’t thought about it for years.

But scientists don’t know how that happens. The brain records many things in short-term memory but only a few make it into long-term storage. The hypothesis is that the brain has a mechanism to strengthen the synapses, or active connections between nerve cells, that encode memories that the brain deems to be worth keeping longer.

The work described in the NYT article is a big step in understanding that process. Researchers at the SUNY Downstate Medical Center in Brooklyn, working with rats, have identified a protein that accumulates in heavily-used nerve endings, those that receive a lot of input from other neurons. The protein probably has something to do with stabilizing those synapses and creating long-term memories, because the scientists have also found that a drug that interferes with the protein destroys the memory of something the rats had learned weeks or months ago.

One of the tests used by these researchers resembles the water-tank test used by Jay Wright and his colleague Joe Harding, but instead of having the rats remember where a platform is in a pool of water, the rats must learn to avoid a sector of the round chamber they’re enclosed in. They get a shock to the feet if they step onto that sector. The rats quickly learn where they can safely go, but one shot of the drug into the part of the brain that stores spatial memories completely obliterates that learning. [View an illustration]

After describing the experiments, writer Benedict Carey delves into the ethical questions we will face if such a drug becomes available for human use. His discussion reminded me of the delightful, offbeat movie “Eternal Sunshine of the Spotless Mind,” with Kate Winslet, Jim Carrey, and Tom Wilkinson, in which a heartbroken man seeks treatment from a company that claims it can erase painful memories.

But the man’s memories of his former sweetheart keep surfacing in unexpected ways. The movie suggests that those memories are still there in his brain, somewhere, waiting, until the right circumstances prompt them to emerge again. It’s art, not science, but it fits our experience. Sometimes we remember that we used to know something, although we can no longer recall the something. How does that happen? If we’ve lost the memory of the thing, why didn’t we also lose the knowledge that we once had that memory? Why is a memory of having a memory stronger than the memory itself?

That’s one of the great pleasures of writing and reading about science: the questions keep getting deeper, and they don’t end.


“Brain Researchers Open Door to Editing Memory.New York Times, April 6, 2009:

Multimedia from the NYT article: Illustrations of research on erasing memory