Traumatic brain injuries have left more than five million Americans permanently disabled. They have trouble focusing on even simple tasks and often have to quit jobs or drop out of school.
A study published on Monday has offered them a glimpse of hope. Five people with moderate to severe brain injuries had electrodes implanted in their heads. As the electrodes stimulated their brains, their performance on cognitive tests improved.
If the results hold up in larger clinical trials, the implants could become the first effective therapy for chronic brain injuries, the researchers said.
“This is the first evidence that you can move the dial for this problem,” said Dr. Nicholas Schiff, a neurologist at Weill Cornell Medicine in New York who led the study.
Gina Arata, one of the volunteers who received the implant, was 22 when a car crash left her with fatigue, memory problems and uncontrollable emotions. She abandoned her plans for law school and lived with her parents in Modesto, Calif., unable to keep down a job.
In 2018, 18 years after the crash, Ms. Arata received the implant. Her life has changed profoundly, she said. “I can be a normal human being and have a conversation,” she said. “It’s kind of amazing how I’ve seen myself improve.”
Dr. Schiff and his colleagues designed the trial based on years of research on the structure of the brain. Those studies suggested that our ability to focus on tasks depends on a network of brain regions that are linked to each other by long branches of neurons. The regions send signals to each other, creating a feedback loop that keeps the whole network active.
Sudden jostling of the brain — in a car crash or a fall, for example — can break some of the long-distance connections in the network and lead people to fall into a coma, Dr. Schiff and his colleagues have hypothesized. During recovery, the network may be able to power itself back up. But if the brain is severely damaged, it may not fully rebound.
Dr. Schiff and his colleagues pinpointed a structure deep inside the brain as a crucial hub in the network. Known as the central lateral nucleus, it is a thin sheet of neurons about the size and shape of an almond shell.
The human brain has two such structures, one in each hemisphere. They seem to help the brain quiet itself at night for sleep and rev up the brain in the morning. Stimulating the neurons in these regions can wake up a sleeping rat, Dr. Schiff’s research has shown.
