Most of us may balk at the thought of a neural implant nestled within our brains (emphasis on most). But the technology first revolutionized decades ago, can now restore the ability to speak and walk while offering relief from conditions like depression and obsessive-compulsive disorder.
Now, new advancements in brain implants are also providing therapeutic answers for patients with traumatic brain injury, a major source of disability worldwide and one impacting more than five million Americans.
A study published Monday in the journal Nature Medicine details the results of a small, phase 1 clinical trial that featured implanted electrodes within the brains of five individuals with moderate to severe brain injuries. For 12 hours a day, the electrodes delivered electrical stimulation, particularly to an area deep in the brain called the central lateral nucleus — a part of the thalamus that helps control alertness, awareness, and sense control. After three months of this deep-brain stimulation, all the participants scored 15 to 55 percent higher on a battery of cognitive tests than before receiving the implant.
“These participants had experienced brain injury years to decades before, and it was thought that whatever recovery process was possible had already played out, so we were surprised and pleased to see how much they improved,” co-author Nicholas Schiff, a professor of neurology and neuroscience at Weill Cornell Medicine’s Feil Family Brain and Mind Research Institute, said in a press release.
The participants, which included four men and one woman, ranged in age from 22 to 60 years old and had traumatic brain injuries sustained three to 18 years prior to the clinical trial. The researchers targeted the central lateral nucleus because it acts as an on-and-off switch of a brain circuit called the “mesocircuit,” which runs executive cognitive functions like attention, planning, and memory. Scientists believe that traumatic brain injuries impair this circuit as well as damage the central lateral nucleus.
In a 2007 study, Schiff and colleagues discovered that deep-brain stimulation to this brain area in one person with severe traumatic brain injuries improved their cognition and behavior. This and subsequent studies suggested that delivering electrical impulses to the central lateral nucleus might be able to reawaken the mesocircuit.
The results of this new study have been five years in the making, as the participants’ implants were surgically placed back in 2018. After two weeks of fine-tuning and making sure no one experienced serious side effects, the stimulation was turned on for 12 hours a day and turned off at night. Before implantation, the participants had their cognitive function tested with neuropsychological tests that judged their ability to concentrate, focus, and plan. Three months of the treatment saw the participants improving their testing speed by 32 percent on average, which far exceeded the 10 percent the researchers hoped to achieve.
“The only surprising thing is it worked the way we predicted it would, which is not always a given,” Jaimie Henderson, a professor of neurosurgery at Stanford Medicine, who also co-authored the study, said in a press release.
The participants have had their brain implants for some years now and report their lives have completely improved. Driven by the success of this trial, the researchers are now gearing up for a phase 2 clinical trial with at least 25 to 50 participants. The hope is to see how well the treatment works for other types of traumatic brain injuries and to experiment with tweaking the implant if need be.
“There’s a long road ahead,” Schiff said in the press statement, ”but at least we have a road.”
