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People who have had a severe traumatic brain injury often struggle to remember recent events or conversations. So brain scientists are looking for ways to help. NPR's Jon Hamilton reports on an approach that delivers tiny pulses of electricity to improve short-term memory.
JON HAMILTON, BYLINE: Most traumatic brain injuries, or TBIs are the mild type - a concussion. A fall or blow to the head causes symptoms that typically last a few days or weeks. Severe TBIs are far less common. But Dr. Ramon Diaz-Arrastia says they can permanently impair a person's thinking and short-term memory.
RAMON DIAZ-ARRASTIA: We see this a lot. This is a very common source of disability.
HAMILTON: Diaz-Arrastia directs the TBI Clinical Research Center at the University of Pennsylvania. Among his patients are young men who were injured in a car or motorcycle crash. He says they often recover physically, but not mentally.
DIAZ-ARRASTIA: We have patients, for example, whose family cannot leave them alone at home because, you know, they will turn on the stove and forget to turn it off.
HAMILTON: Diaz-Arrastia says even less-disabled patients are frequently unable to go back to work.
DIAZ-ARRASTIA: People that are having trouble remembering what they read five minutes ago or having trouble remembering what they were told five minutes ago are going to have a lot of problem holding the vast majority of jobs.
HAMILTON: So Diaz-Arrastia has been working with a team of scientists to restore damaged memory. One of them is Michael Kahana, a professor of psychology at Penn. For years, Kahana has been studying why even a healthy person's memory works well sometimes and not so well other times.
MICHAEL KAHANA: My memory is different than it was an hour ago or than it will be an hour from now. And it's that variability which may open the door to a whole host of potential ways that we can help people improve.
HAMILTON: By tweaking the brain so that it performs as well as it does in the best hour of its best day. Kahana's team started out by having a computer learn to recognize the electrical signals associated with retrieving a memory.
KAHANA: We can predict in a moment-to-moment basis when memory will fail or succeed within a given person.
HAMILTON: Next, the team devised a system that could deliver a precisely timed pulse of electricity to a brain area just behind the ear.
KAHANA: It would detect that you're about to have a memory lapse, and it would try to jostle the system into a state that's more conducive to good function.
HAMILTON: The system worked in a small group of people without a history of TBI. That's when Kahana teamed up with Diaz-Arrastia, the TBI expert, to put together a new experiment.
KAHANA: So in this study, for the first time, we actually tested this therapy in patients who had a history of moderate to severe traumatic brain injury.
HAMILTON: The study, which appears in the journal Brain Stimulation, involved eight people. Like previous participants, all were being evaluated for severe epilepsy, so they already had wires inserted in their brains. Scientists use these wires to both monitor activity and deliver electrical pulses. Kahana says the participants were shown a list of words.
KAHANA: Common English words like key, car, rose, cat, book, lamp.
HAMILTON: Then they tried to remember which words they'd seen. Kahana says when the system saw that a person was about to have a memory lapse, it sent an electrical pulse to that brain area behind the ear.
KAHANA: By electrically stimulating at only moments when you were predicted to fail, we were able to move the brain from a poor state into a better state.
HAMILTON: Stimulation improved their accuracy by about 20%, suggesting that it reduced their memory deficit by about half. Kahana has a financial interest in one company that plans to commercialize this technology. Several other companies are also working on brain stimulation systems. The systems are designed to boost memory and thinking in people with a range of conditions, including Alzheimer's disease. Jon Hamilton, NPR News.
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