How scientists have been manipulating the human brain in recent years is as fascinating as it is frightening. The folks at Neuralink, for instance, believe they will someday be able to connect our gray matter with our smartphones so we can call someone simply by thinking about it. Researchers at the University of California, Davis, meanwhile, have used a brain-computer interface to allow a man rendered speechless by amyotrophic lateral sclerosis (ALS) to make himself heard. And just last month, the Food and Drug Administration (FDA) approved a brain-stimulation implant that promises to ease the symptoms of Parkinson’s.
All this may seem like hyperbolic meandering around the edges of the neuroscience frontier, but for Keith Krehbiel, those electrodes affixed to his brain offer a real benefit. Diagnosed with early-onset Parkinson’s in 1997 at the age of 42, the Stanford University political science professor had relied for years on mega-doses of drugs to calm the involuntary muscle movements, known as dyskinesia, that often characterize the disease. But after enrolling in a clinical trial involving a novel version of deep brain stimulation (DBS), Krehbiel was relieved to find that his symptoms eased substantially.
“My tremor went away almost entirely,” he tells Scientific American. “I reduced my Parkinson’s meds by more than two-thirds. And I no longer have a sensation of a foggy brain, nor nausea or dyskinesia.”
The treatment employs a DBS device planted in his chest to send electrical signals via micro-thin wires connected to a sector of his brain that governs movement. Like a cardiac pacemaker, this model adapts its pulses to the brain signals of the person rather than delivering constant stimulation. The personalized delivery system makes it more precise and effective than earlier DBS iterations.
“Traditional DBS delivers constant stimulation, which doesn’t always match the fluctuating symptoms of Parkinson’s disease,” notes neurologist Todd Herrington, MD, PhD, one of the trial’s investigators. “[T]he goal is to adjust stimulation in real time to provide more effective symptom control, fewer side effects, and improved patient quality of life.”
For Casey Harrell, the brain-computer interface (BCI) that researchers implanted in his frontal lobes allowed him to finally recapture the voice ALS had stolen. He’d lost control of the muscles in his mouth, tongue, larynx, and vocal cords, so it was very difficult for people to understand what he was saying. “Not being able to communicate is so frustrating and demoralizing. It is like you are trapped,” he says. “Something like this technology will help people back into life and society.”
The procedure, part of the ongoing BrainGate clinical trial, involved implanting a device that translates activity in the part of the brain that controls speech into text on a computer, which then “speaks” — in a voice that sounds like Harrell’s in his pre-ALS days.
“We’re really detecting their attempt to move their muscles and talk,” explains neuroscientist Sergey Stavisky, PhD, the study’s co-principal investigator. “We are recording from the part of the brain that’s trying to send these commands to the muscles. And we are basically listening into that, and we’re translating those patterns of brain activity into a phoneme — like a syllable or the unit of speech — and then the words they’re trying to say.”
After three training sessions, the system correctly translated Harrell’s BCI-facilitated speech about 97 percent of the time. The results of the 2024 study were published in The New England Journal of Medicine.
As remarkable as these advances appear in clinical trials, I worry that our instinctive yearning for miracle cures — and the healthcare industry’s predictable craving for increased profits — will tempt scientists to move a bit too quickly on this neurotechnology front. (I can already imagine the marketing ads: “Ask your doctor if implanting electrodes in your brain is right for you!”)
I’m not alone in my concerns. Multiple studies in recent years have warned that housing a foreign object inside your brain is not necessarily a good idea. A 2021 report in Frontiers in Neuroscience warned of “novel risks,” including migration of the implant and brain tissue damage from the electrodes. There’s also the chance that the implant could cause brain bleeds and chronic inflammation, according to a 2021 study in Current Opinion in Biotechnology. And, in what should be a cautionary message, the FDA last week ordered a recall of Medtronic embolization devices used to treat brain aneurysms after the deaths of four patients who were using the devices.
The problem with implanting electronic devices in the brain, it seems, is that the brain may be particularly sensitive to bacterial invasions — from the gut. That’s what a team of researchers at Case Western Reserve University recently discovered after implanting microelectrodes in the brains of lab mice. The subsequent presence of gut bacteria there, they note in Nature Communications, suggests a breach in the blood-brain barrier caused by the implantation of the device.
“This is a paradigm-shifting finding,” lead study author George Hoeferlin, PhD, argues. “For decades, the field has focused on the body’s immune response to these implants, but our research now shows that bacteria — some originating from the gut — are also playing a role in the inflammation surrounding these devices.”
Some of the bacteria they found in the brains of the mice have been linked to Alzheimer’s, Parkinson’s, stroke, and other neurological diseases. This suggests that scientists need to rethink their approach to preventing — and treating — the risks of brain implantation, notes Jeff Capadona, PhD, who led the study.
“If we’re not identifying or addressing this consequence of implantation, we could be causing more harm than we’re fixing,” he says. “This finding highlights the urgent need to develop a permanent strategy for preventing bacterial invasion from implanted devices, rather than just managing inflammation after the fact. The more we understand about this process, the better we can design implants that work safely and effectively.”
Of course, none of this probably matters to Keith Krehbiel, Casey Harrell, and many others suffering from a debilitating neurological disease. The rewards for them may well outweigh the risks. But, for the rest of us, it’s probably a good idea to approach this evolving technology with a somewhat lower level of zeal than, say, the folks at Neuralink who tout their thought-provoking connection between our brains and our smartphones as a step toward “redefining the boundaries of human capabilities.”
That may eventually prove to be the case, I suppose, but it does raise some questions beyond the risks and rewards of a brain implant. I mean, if every time I thought about calling someone resulted in an actual phone call, I’d be spending an awful lot of time apologizing for what may become known as a revolutionary redefinition of butt dialing.
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