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It's Trying To Remember

Brain works more to recall a memory than to make one

FRIDAY, June 1, 2001 (HealthDayNews) -- If a study of fruit flies is any indication, scientists say we use more of our brains to retrieve a memory than we do to make a memory in the first place.

Researchers at Cold Spring Harbor Laboratory on Long Island say they have discovered that how a memory is formed and stored is not how it is recalled. They say the finding could lead to new drugs to preserve or even enhance memory.

"It's another piece of evidence that supports the notion that initial stages of memory are chemical, not electrical," says Tim Tully, a neurogeneticist and co-author of the study, which was reported last week in Nature.

Tully and his colleagues put a mutant form of a gene called shibire, which is involved in the release of neurotransmitters in fruit flies, into the part of their brain responsible for memories. Neurotransmitters are the chemicals neurons use to communicate with each other. The mutated gene allowed the scientists to switch the flies' brains on and off at various points of the memory process. The mutated gene shut the brain down at high temperatures by blocking neurotransmitter activity.

When the brain was disabled during the first two stages of memory -- formation and storage -- the flies remembered to stay away from an odor they had been trained to avoid. But when their brains were deactivated during the third stage -- recall -- the flies could not remember what odor to avoid.

Lead author Josh Dubnau says a key part of the study was finding a way to turn the brains of fruit flies on and off during the memory process. By using the mutant gene, the researchers found that different parts of the brain do not have to communicate with each other to store a memory, but they do need to communicate to recall that memory, he says.

The discovery could shed light on how the human brain makes and uses memory, he says.

"There's lots of evidence that the way memories are formed is essentially identical in all animals. Humans have bigger circuits, and it's more complex, but how information is stored is similar. We do this in the fly because we can. We have a lot of confidence that we can apply it to humans," Dubnau says.

"I think it's neat that they came up with a very ingenuous way of turning the brain on and off. One of the messages with this kind of research is that the building blocks are the same with all species," says Tim DeVoogd, an associate professor of psychology at Cornell University.

DeVoogd says the study shows that if you quiet part of the brain, you can learn but not remember. That's because only a tiny part of the brain is used to make a memory while a larger portion of the brain is needed to retrieve a memory. For example, he says trying to remember someone's name requires a sorting process which is much more complicated than simply hearing the name in the first place.

"I think demonstrating this concretely is new," he says.

Craig Kinsley, a professor of neuroscience at the University of Richmond in Virginia, says, "As far as the implications of the study, I think what they're tapping into is the underlying process of learning. What's fascinating about it is that it's a self-contained demonstration of the memory process."

As for future treatments that might spring from this research, Dubnau says, "It's difficult to say at this stage how this will link to cognitive therapy."

What To Do

For more on memory and the mind, check Zeal.com.

Check this MSNBC article to find out more about how memories are made.

For more HealthDay stories on memory, click here.

SOURCES: Interviews with Tim Tully, neurogeneticist, and Josh Dubnau, neurogeneticist, Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y.; Tim DeVoogd, professor of psychology, Cornell University, Ithaca, N.Y., and Craig Kinsley, professor of neuroscience, University of Richmond, Richmond, Va.; May 24, 2001, Nature
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