A little brain stimulation at night appears to help people remember what they learned the previous day, a study of 18 severe epilepsy (癫澜) patients has found.
During sleep, brain cells fire in rhythmic patterns. When two brain areas synchronize (同步) their firing patterns, they are able to communicate. During non-rapid eye movement sleep, the hippocampus, found deep in the brain, synchronizes its activity with the prefrontal cortex, which lies just behind the forehead. This helps transform memories from the day into memories that can last a lifetime.
Dr. Itzhak Fried at the University of California and his team gathered 18 epilepsy patients who already had electrodes (电极) in their brains for medical evaluation. This offered the scientists a way to both monitor and change a person's brain rhythms. They used a "celebrity pet" test in which participants were shown images matching a particular celebrity with a specific animal. The goal was to remember which animal went with which celebrity.
Patients saw the images before going to bed. While sleeping, some of them got tiny electrical stimulation through the wires in their brains. In patients who got the stimulation, rhythms in the two brain areas became more synchronized. And when they woke up they scored higher on the test.
The experiment was based on decades of research done by scientists, including Dr. György Buzsáki, a neuroscientist at New York University. But changing rhythms in healthy peoples' brains might not improve their memory, he says, because those communication channels are already in perfect condition. The epilepsy patients may have improved because they started out with sleep and memory problems caused by both the disorder and the drugs used to treat it.
Even so, he says, the approach has the potential to help millions of people with damaged memory. And brain rhythms probably play parts in many other problems. "They are not specific to memory. They are doing a lot of other things," Buzsáki says, like regulating mood and emotion.