by Traumatic brain injuries have left more than 5 million Americans with permanent disabilities. They have difficulty concentrating on even simple tasks and often have to quit a job or drop out of school.
A study published on Monday gave them a glimmer of hope. Five people with moderate or severe brain injuries had electrodes inserted into 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 be the first effective therapy for chronic brain injuries, the researchers said.
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“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 accident left her with fatigue, memory problems and uncontrollable emotions. She abandoned her plans for law school and lived with her parents in Modesto, California, unable to hold down a job.
In 2018, 18 years after the accident, Arata received the implant. Her life has changed a lot, she said. “I can be a normal person and have a conversation,” she said. “It’s amazing how I’ve seen myself improve.”
Schiff and his colleagues designed the test based on years of research into the structure of the brain. Those studies suggested that our ability to focus on tasks depends on a network of brain regions connected to each other by long neuronal branches. The regions send signals to each other, creating a feedback loop that keeps the entire network active.
A sudden strain on the brain—in a car accident or a fall, for example—can break some of the long-range connections in the network and lead people to fall into a coma, Schiff and his colleagues have hypothesized. During recovery, the network may be able to power itself up. But if the brain is severely damaged, it may not fully rebound.
Schiff and his colleagues identified a deep structure within the brain as a critical core in the network. Called 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 calm itself at night for sleep and refresh the brain in the morning. Stimulating the neurons in these regions can wake up a sleeping rat, Schiff’s research has shown.
These studies raised the possibility that stimulation of the central lateral nuclei could help people with traumatic brain injuries regain their focus and attention.
Surgeons routinely implant electrodes in patients with Parkinson’s disease. The tiny electrical pulses, which the implants fire hundreds of times a second, instruct neighboring neurons to lock in their own signals, restoring some brain functions.
In 2018, Schiff and his colleagues began recruiting volunteers, including Arata, who suffered from chronic problems for years after their accidents. Before the electrodes were inserted, the researchers gave the volunteers a battery of tests to assess their ability to focus and switch tasks. In one test, for example, volunteers were given a sheet of paper covered in letters and numbers and had to draw a line connecting them in order as quickly as possible.
Before the surgery, the researchers scanned each volunteer’s brain to create a precise map. Dr. Jaimie Henderson, a neurosurgeon at Stanford University, guided the electrode through the brain, to the central lateral nucleus.
Henderson implanted the electrodes in six volunteers, but one of them had to drop out of the study after developing a scalp infection. Starting one month after surgery, the other five volunteers underwent follow-up tests. In the letter and number test, their scores jumped anywhere from 15% to 52%.
To gain a broader understanding of the volunteers’ experiences, Dr. Joseph Fins, a medical ethicist at Weill Cornell Medicine, conducted a series of interviews with them and their families. Most of the volunteers, including Arata, said the implant made them more like their real selves.
In contrast, the volunteer who saw the greatest improvement on cognitive tests had a lukewarm reaction. “I don’t think it’s hurt,” he said. “I don’t know if it helped much.”
And yet the son of that patient saw significant changes, especially in his father’s self-awareness. “It is night and day,” said the son.
Dr Steven Lareys, a neuroscientist at the University of Liège in Belgium who was not involved in the study, said the findings supported the theory that attention and other forms of thinking depend on the brain’s network. “There’s a lot of reason to believe it’s worth pursuing,” he said of the research.
Schiff and his colleagues are planning a much larger study of the brain implants. “We have to see how the data shakes out,” he said.
The lateral central nuclei are not the only regions showing promise as hubs in the brain network, said Dr. Alex Green, a neurosurgeon at the University of Oxford who was not involved in the study.
“We still don’t know where to give encouragement,” Green said. He and his colleagues are preparing their own brain injury trial to test electrodes in a region called the pedunculopontine nucleus.
Lareys acknowledged that implant surgeries would be expensive but argued that society should recognize the millions of people who suffer from traumatic brain injuries. “This is a silent epidemic,” he said.
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