Deep Brain Stimulation Trials Restore Speech, Movement

GLENN HARVEY

Conditions & Treatments

How Revolutionary Brain Implants Are Beginning to Restore Abilities and Combat Disease

In trials with a handful of patients, new technologies help improve movement and speech 

By Michael Greshko, AARP

Published November 20, 2024

Imagine a brain chip capable of decoding thoughts and intentions in ways that could help a person speak or move again, years after losing these skills to a devastating illness or injury.  

It may sound like science fiction, but in laboratories around the world, researchers are developing therapies that rely on devices called brain-computer interfaces (BCIs for short) to help

address several serious health issues that affect many adults age 50-plus.

You may have heard of this idea before: A brain-implanted chip was first used to control a computer cursor nearly two decades ago, in 2006. Or you may have seen more advanced BCIs in the

news recently. Tech billionaire Elon Musk’s brain-implant company Neuralink launched its first human clinical trial this year and planted a brain chip in a 30-year-old man who was paralyzed

below the neck after an accident in 2016.

Neuralink's first trial participant, Noland Arbaugh, was able to play digital chess and video games with the brain chip implant.

Rebecca Noble/The New York Times/Redux

The device — which is about the size of a quarter and sits near the top of the skull above the ear, while its wires weave through an area of the brain that controls movement and intention —

allows a person to control a computer cursor with their thoughts. The first patient in the trial, for example, was able to play digital chess and video games with the chip. A second

participant who received the brain chip over the summer is learning how to use computer software to design 3D objects that are then printed.

Neuralink sees this capability as a first step toward potentially creating a seamless interface between the human brain and computers. If computers could one day decode brain activity very

quickly and accurately, they could power technologies that could help restore complete autonomy to people who have lost sight, speech or movement. 

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“Taking an idea, putting it as a design, and actually having a physical item as a finished product makes me feel like I’m building things again,” the second trial participant said in a post

on Neuralink’s website.

Neuralink is just one of many private businesses and university research labs developing new BCI technologies, and others are working to improve brain implants we already have. And though it

will be years before innovations make their way through the regulatory process and into doctors’ offices, it’s still “a really exciting time for neurotechnology right now,” says David

McMullen, M.D., director of the Office of Neurological and Physical Medicine Devices at the U.S. Food and Drug Administration (FDA), which oversees BCIs.

Here’s a look at what’s happening.  

How we are already using — and improving — brain implants

First, know that some people are already benefiting from brain and spine implants.

Around the world, about 34,000 people per year receive spinal cord stimulators, devices that are implanted next to the spinal cord and release low-level electrical pulses that help manage

types of back pain. And for more than two decades, a treatment known as deep-brain stimulation (DBS) has been used to safely and effectively manage some symptoms of Parkinson’s disease, a

brain disorder that can cause balance problems, tremors and slowed movements. It affects an estimated 1 million U.S. adults, most of whom are 60 and older.  

can help people with movement disorders.

To date, more than 200,000 DBS implants worldwide have been placed within patients to treat Parkinson’s and other disorders. Here’s how it works: A surgeon implants a thin wire, called a

lead, into a specific region of the brain that, in Parkinson’s patients, produces irregular signals that cause tremor and other movement problems. The lead’s tip contains several metal wires

called electrodes that can send out electrical pulses more than 100 times per second into the surrounding nerve cells in the brain. These pulses can drown out the problematic brain signals

like a white-noise machine, helping to quell tremors and other movement symptoms. 

For Florida resident Bruce Ryan, the idea of lodging something in his brain to help tame his tremors seemed “crazy” at first. “I just couldn’t imagine that happening to me,” says Ryan, 61.

But his tremors were interfering with daily life. He didn’t want to go out to eat for fear of spilling something, and he couldn’t easily sign his name. So, he had the procedure.

Now, roughly five years later, Ryan said the difference it’s made in his life has been “profound.” 

“It’s hard to put in words, but it’s one of the best decisions I’ve ever made in my life,” he says.

Though DBS is now a mature technology, researchers are still trying to improve it. For example, DBS pulse generators — devices implanted beneath the patient’s skin near the chest that send

electrical signals to the wires in the brain — are getting smaller. And the batteries that power them, which once had to be changed every three to five years, are now rechargeable, lasting

much longer.  

Their controllability is also improving. Updated designs allow doctors to fine-tune the pulses to maximize their therapeutic benefit and minimize any potential side effects, such as slurring

of speech that some people experience from the pulses interfering with healthy brain signaling.  

How deep brain stimulation works: A neurotransmitter placed in the chest, usually under the skin near the collar bone, sends electrical signals that are carried by a wire to targeted areas

in the brain that control movement.

“You’re trying to disrupt abnormal information flow and minimally disrupt normal information flow,” says Kelly Foote, M.D., a neurosurgeon at the University of Florida College of Medicine

who specializes in DBS.

Researchers are also trying to make DBS implants more efficient. Currently, dialing in the exact intensity and frequency of pulses is a trial-and-error process — and it’s one that needs to

be adjusted as the disease worsens. Ideally, “the device could just program itself and turn itself on and off or up and down to meet the needs of that patient,” Foote says.

We’re not there yet, but research on such an adaptive device — known as a “closed loop” device — is well underway for people with both essential tremor and Parkinson’s disease.

To date, more than 200,000 DBS (deep brain stimulation) implants have been placed within patients to treat Parkinson’s and other disorders.

Josh Letchworth  

Building tomorrow’s brain implants

We’re not just seeing advancements in well-established brain implants. Here’s a look at new technologies that could one day change the way we treat a number of health issues.  

Recovering movement

One of the leading groups in this space is Switzerland’s NeuroRestore research center. In a NeuroRestore study published last May in the journal Nature, a team led by Lausanne University

neurosurgeon Jocelyne Bloch and Grégoire Courtine of the Swiss Federal Institute of Technology Lausanne unveiled a closed-loop “digital bridge” that could reconnect the brain and spinal cord

after an injury had severed them. 

In a small-scale human clinical trial, the researchers worked with Gert-Jan Oskam, a 40-year-old Dutch man who was told he would never walk again after breaking his neck in a cycling

accident in 2011. The team implanted 64 electrodes over the surface of Oskam’s motor cortex, the brain region responsible for controlling his movement.

Gert-Jan Oskam, a 40-year-old Dutch man, was told he would never walk again after breaking his neck in a cycling accident. He had 64 electrodes implanted in the region of his brain

responsible for controlling movement.

Jimmy Ravier/EPFL

These electrodes sensed Oskam’s brain activity and then sent those signals to a computer that parsed out Oskam’s movement intentions. These signals, in turn, were sent to a pulse generator

that sent electrical pulses into a 16-electrode lead implanted beside Oskam’s spinal cord. In effect, these pulses mimicked signals that Oskam’s brain would have sent down the spine before

his injury cut the connection. The system can detect a movement that Oskam is trying to make and then quickly transmit that signal to his spine. Combined with regular physical therapy, the

system let Oskam walk with crutches and a walker-like device. And over a three-year period, Oskam’s consistent use of the system improved his neurological recovery: He can now walk

independently for short distances with crutches, without needing to use the system.

“Honestly, I can tell you, I think this is the most impressive thing I’ve ever seen,” says NeuroRestore member Eduardo Martin Moraud, a clinical neuroscientist at the University Hospital in

Lausanne.  

The technology can detect a movement that Oskam is trying to make and then quickly transmit that signal to his spine. Combined with regular physical therapy, the system let Oskam walk with

crutches and a walker-like device.

Jimmy Ravier/EPFL

The NeuroRestore group has also been working on treatments for Parkinson’s disease. People with Parkinson’s can be prone to falls and what’s known as freezing gait: a sudden stopping of

movement or inability to move, especially when approaching a doorway. In a study published in November 2023 in the journal Nature Medicine, Moraud and colleagues unveiled a system that uses

a spinal implant in concert with four inertial sensors — like the ones that detect when a smartphone is tilted at an angle — to correct the walking gait of a person with Parkinson’s.

Unlike DBS, which adds electrical “white noise” to the brain, this system predicts which kinds of signals ought to be reaching the spine and sends those out into the spinal cord.

This system uses a sophisticated model of how nerve signals activate the body’s muscles to automatically correlate the person’s gait with the nerve signals that the brain should be sending

to the legs. It then sends corrective pulses of electricity to electrodes surgically implanted next to the spinal cord. When using the implant in combination with three months of physical

therapy, the study’s main test subject — a man from Bordeaux, France, named Marc Gauthier, who was 62 at the time of the study — saw his freezing gait almost vanish and the overall quality

of his walking gait improve.

Gauthier has been using the device for roughly three years, for about eight hours per day. He now takes miles-long nature walks around a lake. “I can walk better, I am less unbalanced, and I

think that stairs don’t scare me anymore,” he said in patient testimony included with the 2023 study. “Now, I can walk five kilometers without any stops.”

Restoring speech

Other research teams are working to restore speech in people who have lost it. Two studies published side-by-side in Nature in August 2023 unveiled brain implants that could synthesize

speech from recordings of brain activity. Working at between 60 and 70 words per minute, these systems are currently about half as fast as natural conversation — but they are more than

three times as fast as similar systems that came before them.

One of these systems, developed by a team led by University of California, San Francisco neurosurgeon Edward Chang, M.D., even came up with a way to use brain activity to animate a digital

avatar. This study’s participant, a 48-year-old woman named Ann Johnson, suffered a stroke in her brain stem in 2005 and was left paralyzed and unable to speak. The system could decode

Johnson’s brain activity and decipher her intentions to move her facial muscles and vocal tract — and then translate these signals into synthetic speech and corresponding animations of a

digital face.  

Ann Johnson suffered a stroke in her brain stem in 2005 and was left paralyzed and unable to speak. Brain implants helped her communicate. 

Noah Berger

In part, this study depended on electrodes implanted onto the upper surface of Johnson’s brain. There are inherent tradeoffs to these arrays, which have been around for years, but like DBS,

these technologies are being improved and refined. Implanting them in the brain improves signal quality — meaning that they can record brain signals in greater detail — but it also increases

the risk of infection.

Implanted devices must also resist corrosion, and then there’s the challenge of outwitting the body’s natural immune response, which may recognize the implant as a foreign substance and

surround it with scar tissue, worsening its performance. “Making these things stable over time is very difficult,” Moraud says. “After a year, maybe you don’t even sense anything anymore.”

Companies are trying to get around these issues by working with substances that are less likely to break down in the brain, for example, or making their electrodes extremely thin to minimize

risk of tissue damage. Neuralink’s “threads” of electrodes are between 4 and 6 microns thick — about 5 percent the thickness of a sheet of printer paper.

Even still, the technology needs tweaks. In the case of Neuralink’s first trial participant, 85 percent of the implant’s 64 threads stopped working several weeks after surgery, after many of

the threads had retracted out of the brain tissue. The company says it has since stabilized these threads and the study participant is back to being able to use his implant to control his

computer. In its August update, Neuralink reported that it had not seen any threads retract from the second participant’s brain tissue.

What This Means for You: The Lowdown on Brain-Computer Interfaces (BCIs) 

When will BCIs be available?  

Some technologies, like deep brain stimulation (DBS), are already here. Others may be decades away from widespread availability. The regulatory approval process often takes years, and not

every technology in the pipeline gets approved.  

How much will it cost? 

Because many of these cutting-edge technologies are not available yet, costs are unknown. Some will probably be at least as expensive as DBS, which can cost upwards of $30,000, according to

estimates. Medicare will cover the DBS procedure for some patients who meet the criteria; the same goes for private insurers.  

What will BCIs be used for? 

Researchers are studying BCIs and spine implants across a range of conditions, including:  

Parkinson’s disease and other movement disorders   Obsessive-compulsive disorder and depression  Loss of speech   Cognitive impairments from traumatic brain injury   Paralysis   Seizures  

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Kelly Foote, M.D., is a neurosurgeon at the University of Florida College of Medicine who specializes in deep brain stimulation.

JOSH LETCHWORTH

A challenging road to clinical use

Experts stress that advanced BCIs face a long, winding road of tests and trials before they will become clinically available — and that as extraordinary as the technology’s potential is, it

won’t be a cure-all.

For one, even the most advanced brain implant will yield minimal benefit if it’s not implanted in precisely the right spot, requiring a highly skilled team of specialists. “The difference

between here to California, in brain-space, can be less than a millimeter,” says Michael Okun, the director of the University of Florida’s Norman Fixel Institute for Neurological Diseases

and medical adviser for the Parkinson’s Foundation.  

Patient-selection criteria are also key when it comes to these technologies. For example, not every Parkinson’s patient will benefit from DBS — in fact, only about 10 to 15 percent of people

with Parkinson’s disease are considered good candidates for the treatment, and fewer still receive it. And while DBS can help with some symptoms of Parkinson’s, it doesn’t address all of

them — nor does it stop or slow the disease’s underlying progression.

Crucially, experts say that BCIs are best seen as just one part of a broader care approach. In the NeuroRestore trials, for example, technology is only part of the equation; often the most

important part is physical therapy. “I think a lot of people think technology alone is solving things,” Moraud says. “Technology is allowing physical therapy to work better.”

BCIs are still so new that physicians, device manufacturers and government regulators alike still have a lot of details to sort out.

“Who’s going to be part of that care team [for a BCI implantation]? How is that care delivered? How is it paid for?” McMullen asks. “All those questions need to be answered so that when one

— or hopefully several — new BCIs go through the process and demonstrate they’re safe and effective, they can actually get to patients and have an impact.”

Michael Greshko is a journalist who has covered science and technology for publications including The New York Times, Science, Scientific American, and National Geographic, where he worked

for seven years as a staff writer. He lives in Washington, D.C., with his family.

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