STEVE INSKEEP, HOST:
What happens when you sleep? While you're sleeping, the brain strengthens memories that it expects to use in the future. Now scientists say they've found a way to enhance that process. NPR's Jon Hamilton reports on research that might someday help people with memory loss from Alzheimer's disease.
JON HAMILTON, BYLINE: There's a lot going on in our brains at night. And Dr. Itzhak Fried, a neurosurgeon at UCLA, says much of this activity involves rhythmic electrical pulses.
ITZHAK FRIED: Brain cells are firing and then pausing, firing and pausing.
HAMILTON: Some of those brain rhythms can help transform a daily event into a memory that can last for weeks or longer, a process called memory consolidation. So Fried and a team of scientists wanted to watch this happen in people.
FRIED: But also trying, actually, to boost memory, to boost this process.
HAMILTON: To do that, the team needed some volunteers, so they approached 18 patients with severe epilepsy. They already had electrodes in their brain, which the team could use to monitor and alter their brain rhythms. Fried says one member of his team created a fun memory test.
FRIED: Or what we call celebrity pet. She presented a certain celebrity with a certain pet. So I think the patient found it engaging.
HAMILTON: The goal was to remember which animal went with which celebrity. Patients saw the images before going to bed. Then while they slept, some of them got tiny pulses of electricity through the wires in their brains. Fried says the pulses were designed to synchronize two distant brain areas involved in memory consolidation - the hippocampus and the prefrontal cortex.
FRIED: So we're measuring the activity in one area deep in the brain. And then, based on this, we're stimulating in a different area.
HAMILTON: The approach worked. Fried says in patients who got the stimulation, rhythms in the two brain areas became more synchronized. And when those patients woke up, they did better on the celebrity pet test.
FRIED: That synchrony really correlated well with the memory improvement.
HAMILTON: Fried says the results, which appear in the journal Nature Neuroscience, need to be confirmed in a larger study. Even so, he says, they suggest a new way to help people with sleep and memory problems.
FRIED: We know, for instance, that in patients with dementia, with Alzheimer, sleep is not working very well at all. The question is whether by changing the architecture of sleep, you can help memory.
HAMILTON: The experiment was based on decades of research done by scientists, including Dr. Gyorgy Buzsaki of New York University. Buzsaki says brain rhythms are how different areas of the brain communicate.
GYORGY BUZSAKI: If you would like to talk to the brain, you have to talk to the brain in its own language.
HAMILTON: Buzsaki says in healthy people, brain rhythms are already optimized. He says these epilepsy patients may have improved because they started out with sleep and memory problems.
BUZSAKI: These people are under medication. These people have perturbed sleep. So maybe what happened here is just making worse memories better.
HAMILTON: Even so, Buzsaki says this approach has the potential to help millions of people with impaired memory. And he says brain rhythms are involved in lots of other critical functions.
BUZSAKI: They are not specific to memory. They are doing a lot of other things - emotions, emotional regulations. They are served by the same kind of rhythms.
HAMILTON: So Buzsaki says tweaking brain rhythms might also help with disorders like depression.
Jon Hamilton, NPR News. Transcript provided by NPR, Copyright NPR.
