Researchers at the University of California, San Francisco (UCSF) have developed a new form of adaptive deep brain stimulation (aDBS) that adjusts therapy in real time as patients walk, improving gait stability and reducing falls in people with Parkinson’s disease.
Published in Nature Medicine, the study demonstrates for the first time that an implanted neurostimulator can detect brain signals associated with individual steps and modify stimulation within fractions of a second. The approach represents a significant advance in personalized neuromodulation and could help address one of the most difficult-to-treat symptoms of Parkinson’s disease.
“Difficulty walking is one of the most disabling symptoms of Parkinson’s disease and one of the hardest to treat,” said senior author Doris D. Wang, MD, PhD, associate professor of neurological surgery at UCSF. “Walking is a highly dynamic behavior that requires precise timing across both sides of the body. We developed a system that can recognize those movement patterns and respond in real time, effectively allowing the stimulation to work with the patient as they move.”
Addressing a major unmet need in Parkinson’s disease
More than 10 million people worldwide are living with Parkinson’s disease, a progressive neurodegenerative disorder characterized by tremor, rigidity, slowness of movement, and postural instability.
Deep brain stimulation has become an established treatment for many motor symptoms of the disease, particularly tremor and rigidity. However, gait impairment, freezing of gait, and falls often persist despite therapy and are major contributors to disability, hospitalization, and loss of independence.
One limitation of conventional DBS is that it delivers continuous stimulation regardless of a patient’s activity. While effective for relatively stable symptoms, this approach may not adequately support complex behaviors such as walking, which require rapid and constantly changing coordination between the brain, spinal cord, and muscles.
The UCSF team hypothesized that stimulation timed to a patient’s actual movements might provide more effective support for gait control.
Turning brain signals into therapeutic feedback
To develop the system, researchers identified neural activity patterns associated with movements of the left and right legs. These movement-related signals were then incorporated directly into an implanted neurostimulator capable of adjusting therapy automatically during different phases of walking.
Unlike previous adaptive DBS approaches that typically respond to slower changes in disease-related brain activity, the new system operates on a timescale of milliseconds and responds directly to behavior itself.
“The brain contains remarkably rich information about movement,” said first author Kenneth H. Louie, PhD, a UCSF postdoctoral scholar. “We found that we could identify neural signatures linked to each step and use them to guide stimulation in real time.”
The researchers liken the device to a cardiac pacemaker. Rather than delivering constant stimulation, the neurostimulator continuously monitors neural signals and dynamically modifies therapy to match the brain’s walking rhythm.
The system performs these adjustments internally without requiring an external computer, making it suitable for real-world use outside the laboratory.
Testing the adaptive system
The study enrolled five individuals with Parkinson’s disease who had previously undergone DBS surgery as part of a UCSF investigational research program.
In addition to therapeutic DBS leads implanted deep within the brain, participants received research electrodes positioned over motor-related cortical regions. These electrodes allowed researchers to record neural activity associated with walking and identify personalized movement signatures for each participant.
Using these individualized neural biomarkers, investigators programmed the implanted device to automatically adjust stimulation during walking.
Laboratory testing demonstrated improvements in several objective measures of gait performance, including increased gait symmetry and reduced variability between steps. Both metrics are associated with more stable and efficient walking patterns.
The researchers then evaluated the system in participants’ daily lives through a blinded, multi-day crossover study comparing periods with adaptive stimulation and periods with conventional stimulation settings.
During adaptive stimulation, participants experienced fewer falls while maintaining overall control of their Parkinson’s symptoms.
No serious adverse events were reported, and participants tolerated the rapid stimulation changes without difficulty.
Although the trial was small, the findings provide early evidence that matching stimulation to behavior may offer benefits beyond those achieved with continuous DBS.
A shift toward behavior-responsive neuromodulation
The study highlights an emerging trend in neuromodulation: moving from static therapies toward systems that continuously sense and respond to changing neural states.
Most adaptive DBS technologies under development focus on biomarkers that fluctuate over minutes or hours. The UCSF approach instead targets neural signals associated with immediate actions, enabling stimulation to respond almost instantaneously.
“This study is about more than walking,” said Wang. “It demonstrates that brain stimulation can adapt to what a person is doing in real time. That opens the door to future therapies that respond dynamically to movement, speech, mood, cognition, and other brain functions.”
The concept could ultimately extend beyond Parkinson’s disease to other neurological and psychiatric disorders in which symptoms vary throughout the day.
Toward intelligent brain implants
Researchers envision future implanted devices that function as closed-loop systems, continuously monitoring neural activity and delivering therapy only when needed.
Such systems could potentially improve treatment efficacy while reducing side effects and conserving device battery life. By tailoring stimulation to specific behaviors or symptoms, clinicians may be able to provide more precise and individualized care.
The work also represents an important technological milestone because the adaptive algorithms were embedded directly within the implanted device rather than relying on external processing hardware.
“This is an important step toward a new generation of brain therapies,” Wang said. “Instead of delivering the same stimulation all day long, future devices may continuously listen to the brain and immediately respond to a patient’s needs. Just as pacemakers transformed the treatment of heart disease, intelligent neurostimulators may transform how we treat disorders of the brain.”
While larger clinical studies will be needed to confirm the benefits of the approach, the results provide an early demonstration that real-time, behavior-responsive neuromodulation may offer a new way to address some of Parkinson’s disease’s most challenging symptoms.
This is today’s edition of The Download, our weekday newsletter that provides a daily dose of what’s going on in the world of technology.
This man with ALS is the first “power user” of a brain implant that lets him speak
Casey Harrell has had a set of electrodes embedded in his brain for almost three years. Harrell, who has ALS and is paralyzed, first used his brain-computer interface (BCI) to “speak” in 2023. Since then, he’s clocked thousands of hours of use.
Harrell can now use the device largely independently. His team has added new features to it, and he also uses it to surf the web and perform his job. “Living with a disease like ALS, you are supposed to have diminished dreams. I do not,” Harrell told MIT Technology Review.
The team behind the device call Harrell “the first power user of a speech BCI.” They now plan to add further enhancements to the device.
While a public backlash against AI brews across the US, South Koreans are optimistic. Only 16% say they are more concerned than excited about AI—the lowest of the 25 countries surveyed by the Pew Research Center—while 50% of Americans were more worried than excited.
South Koreans share a deep conviction that embracing technology is integral to modernizing the country and cementing its place in the global order. Their fascination with AI is just the latest incarnation of that ethos—and it’s making them anxious to stay ahead.
This story is from The Algorithm, our weekly newsletter giving you the inside track on all things AI. Sign up to receive it in your inbox every Monday.
The must-reads
I’ve combed the internet to find you today’s most fun/important/scary/fascinating stories about technology.
1 The US says it restricted Anthropic AI over foreign intelligence risks Commerce chief Lutnick said he acted over national security fears. (Reuters $) + Following the ban, Anthropic disabled access to its new models. (BBC) + Both sides are increasingly desperate for a resolution. (WSJ $)
2 DeepSeek just became China’s most valuable startup It raised $7 billion, the largest-ever first-round funding for an AI startup. (The Information $) + The deal values DeepSeek at over $50 billion. (WSJ $) + Its unusual structure preserves founder control. (Reuters $) + DeepSeek’s new flagship model has caused a stir. (MIT Technology Review)
3 Alibaba has unveiled AI models for robots amid a shift from chatbots It’s joined a global race to move AI into the physical world. (SCMP) + AI is learning to understand its surroundings. (MIT Technology Review)
4 Fox is buying streaming giant Roku for $22 billion The deal creates the third-largest player in US TV by viewing share. (BBC) + Fox is making a big bet on free streaming. (Washington Post $)
5 EA has launched a new way to advertise “directly into gameplay” EA Advertising allows brands to become part of the game itself. (CNBC) + Xbox’s new chief strategy officer is also eyeing in-game ads. (PC Gamer) + GenAI could reinvent what it means to play. (MIT Technology Review)
6 It’s trivially easy to use Reddit to manipulate AI search A tiny snippet of text can trick ChatGPT and Google’s AI search. (404 Media) + AI search is being manipulated to generate dangerous biases. (BBC)
7 Sperm have been made magnetic to allow IVF inside the body The technique enables remote guidance towards an egg. (New Scientist $) + Automation and AI are transforming IVF. (MIT Technology Review)
8 The world’s leading deepfake expert no longer trusts his own eyes He’s struggling to prove what’s real before the internet decides. (NYT $)
9 Meta’s CTO admits its AI reorganisation was “atrocious” He’s promised staff better communication—and snacks. (Wired $)
10 Silicon Valley billionaires are pretending to kill each other for fun In a new game show from Peter Thiel’s Founders Fund. (WSJ $)
Quote of the day
“There was a speeding ticket, and they gave Fable the death penalty.”
—Alex Stamos, the former chief security officer of Facebook, tells the Washington Post that banning foreign access to Anthropic’s leading model is a disproportionate punishment.
One More Thing
VICTOR KERLOW
Inside effective altruism, where the far future counts a lot more than the present
Since its birth in the late 2000s, effective altruism has aimed to answer a deceptively simple question: “How can those with means have the greatest impact?”
Directing money to evidence-based approaches is EA’s best-known technique. But as it’s expanded from an academic philosophy into a community and a movement, its ideas of the “best” way to change the world have evolved as well.
A place for comfort, fun, and distraction to brighten up your day. (Got any ideas? Drop me a line.)
+ The humble table has been reimagined as an unconventional public artifact. + Take a visual tour of the weird, centuries-old history of architecture’s most gruesome gargoyles. + A colorful parakeet unseen for an entire century was triumphantly rediscovered in an unexplored Indonesian forest. + This shimmering Southern Lights timelapse filmed by an astronaut on the SpaceX Dragon is stunning.
Casey Harrell has had a set of electrodes embedded in his brain for almost three years. Harrell, who has amyotrophic lateral sclerosis (ALS) and is paralyzed, first used his brain-computer interface (BCI) to “speak” sentences with the help of a research team in 2023.
Since then, Harrell has clocked thousands of hours of use. He can use the device largely independently, once he’s been “plugged in” with the help of a carer. His team has added new features to it, and Harrell also uses it to surf the web and perform his job.
“Living with a disease like ALS, you are supposed to have diminished dreams. I do not,” Harrell tells MIT Technology Review. “Any one of these things would be an absolute godsend of improvement. To have all of them, and many, many more, is truly revolutionary.”
Within the first 22.6 months after the device was implanted, Harrell had used it for more than 3,800 hours at home without any researchers present, the team reported today in the journal Nature Medicine. “He’s the first power user of a speech BCI,” says team member Sergey Stavisky, a neuroengineer at the University of California, Davis.
Decoding speech
Three years ago, Harrell entrusted David Brandman, an associate professor of neurological surgery at the University of California, Davis, and his colleagues with his brain. Harrell, who was 45 at the time, had already been diagnosed with ALS, a degenerative disease that robs people of the use of their muscles.
Harrell was dependent on others to control his wheelchair and to dress and feed him. He had difficulty speaking; people struggled to understand what he was saying. Then Brandman and his colleagues asked if he’d like to trial a brain implant that might help him communicate. “The industry was [on the] cusp of a transformation, and I wanted to be part of it,” says Harrell. He signed up.
In July 2023, during a five-hour operation, doctors implanted four arrays of 64 electrodes each into his brain. Each pair of arrays was wired to a “pedestal” connection point—creating two docking locations on the exterior of his skull to connect the electrodes to a computer.
The team had long been working on developing algorithms to decode brain activity into speech. Their system works by recording activity from the speech motor cortex—a region of the brain responsible for the movements that allow us to speak.
“There are 39 phonemes that make up all the sounds in the [American] English language,” says Nicholas Card, a neuroengineer at UC Davis and member of the team. Mapping neural activity related to producing each of those phonemes can allow the team to create a personalized speech decoder and software that can “speak” those words. “We first go from brain data to phonemes, and then from phonemes to words,” he says.
They started using the device around a month after the surgery. The team got Harrell’s speech decoder working on the first day, says Card. On that day in August, Harrell used the device to speak with a 50-word vocabulary, and 99.6% of the words were as he’d intended. That vocabulary was later expanded to 125,000 words with 97.5% accuracy.
At the time, it was unclear how long the device might last. Brain-computer interfaces are still new—not many people have had them implanted for long periods of time. Scar tissue can form around electrodes in a person’s brain, interfering with their ability to pick up neural activity, for example. But that doesn’t seem to be the case for Harrell.
Power user
In another advance, Harrell is now able to use the device more independently. In 2023, members of the research team would have to visit Harrell at his home and physically connect and disconnect him from the device on the days he wanted to use it. Not anymore. The team has since automated more of the system—today, Harrell’s care partner can don and doff it for him. “He’ll wake up, get plugged in, and just get going,” says Stavisky.
This is important, says Mariska Vansteesel, a BCI researcher at Utrecht Medical Center who was not involved in the trial. “For these technologies to be relevant for patients, we really need to test them in settings in which they will eventually be used … to demonstrate that it has value, that it’s usable, and that it functions well without the constant involvement of a research team,” she says.
Casey Harrell uses his BCI to speak in “private mode.”
The team has also worked to improve the system itself. It is now 99% accurate, says Stavisky. Harrell can also control a cursor—a game changer that enables him to use his personal computer to send text messages and emails, surf the web, and keep up with his job as an environmental activist.
Over the years, the team has updated the system to accommodate specific requests from Harrell. He is now able to switch on a “privacy mode”—when active, any decoded text will be automatically deleted. He can also opt to use a “profanity filter” while he’s talking to his young daughter.
“We have been able to add on to the software side of the device … improving the accuracy and adding more bells and whistles to enable me to be more independent when using the device,” says Harrell. “We are making the road as we walk it, or roll it, so to speak.”
Nothing short of revolutionary
Vansteesel cautions that while the device is working well for Harrell, there’s no guarantee it will work as well, or as long, for other people with ALS. Over the last decade, she has worked with a woman with ALS who used a fully implanted device to communicate using “brain clicks”—cursor clicks made using brain activity. The woman used her BCI for seven years, but it stopped working toward the end of that period, apparently due to brain degeneration.
At any rate, not everyone with ALS will be willing to undergo invasive brain surgery, says Jane Huggins, who is developing noninvasive BCIs at the University of Michigan and was not involved in the trial. “Long-term, independent use with efficient and accurate communication is kind of the holy grail of BCI,” she says. “But we have been finding a consistent aversion to hospital stays among people with progressive conditions like ALS.”
Harrell, however, calls the device “nothing short of revolutionary.” “This has allowed me to keep working and earn money and insurance for my family. This is reconnecting me with friends and family who are too shy or too afraid to come over and not be able to understand me,” Harrell says. “With my seven-year-old daughter, I am able to create a bond that I wasn’t before able to forge. Now I can read to them and help them sharpen their own reading skills. By doing so, I am able to share the responsibility of parenting with my wife, who does so much caregiving for me and also our daughter.”
Stavisky and his colleagues hope to improve the device further still. “We’re never satisfied,” he says. One aim is to eventually restore Harrell’s “full voice.” They are working on a “brain-to-voice” system that could directly decode brain activity to a speaking voice, complete with natural-sounding cadence, inflection and intonation—a voice that could sound happy, angry, or sarcastic, for example.
“I was quietly confident that I could get some personal benefit from the system,” says Harrell. “Never in a million years would I think that I would achieve this much.”
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<![CDATA[Teens’ pre-bed smartphone scrolling drives more late-night phone use, disrupting sleep and potentially worsening mental health—experts urge bedtime screen limits and device-free bedrooms.]]>
The foreign body reaction to implanted electrodes in the brain has long been recognized as a major challenge impacting the performance and reliability of indwelling neurotechnologies. Spatially resolved transcriptomic approaches have enabled high-resolution mapping of cellular and molecular dynamics at the device-tissue interface, yielding novel insight into both acute and chronic tissue responses. Recent whole-transcriptome profiling methods generate exceptionally dense gene expression datasets from individual samples, offering unprecedented resolution and analytical power. Yet, limited studies have explored aggregated results from larger datasets and sample-to-sample variation within an implanted cohort using such techniques due to high costs and complicated downstream analyses. In this work, we provide a comprehensive report of spatial transcriptomics data collected from an expanded cohort of rats (n = 14 rats) implanted with silicon microelectrode arrays in the motor cortices for 1 week (acute) and 6 weeks (chronic). This larger dataset enabled us to explore the variation in results across samples, assess outliers, and examine potential batch effects. We employed differential expression analysis to identify top differentially expressed genes (DEGs) in spatially defined regions at the device-tissue interface to reveal novel biomarkers in the aggregated dataset. We assessed sample-to-sample variabilities, and applied a factorization strategy to identify prominent cell-type contributors of the top DEGs. Using network-based co-expression analysis, we identified gene modules, hub genes, and central regulatory processes governing the device-tissue interface. Our results show: (a) greater variation of top DEGs across samples at the 1-week time point with notable microglial and astroglial cell-type contributors, (b) lower variation of top DEGs across samples and a shift to prominent astroglial cell-type contributors at the 6-week time point, and (c) novel biomarkers that suggest major macrophage- and microglial mediated processes and homeostasis events at the 1-week time point, and greater tissue remodeling, apoptotic and synaptic changes at the 6-week time point. These findings support previous ideas on the evolving tissue response to implanted devices, and present novel details on biomarkers, biological processes and sample variation. Additionally, this study provides a framework for assessing larger datasets employing high-dimensional spatial transcriptomics and highlight key considerations related to across-sample variability and batch effects.
That’s good for health—one Lancet study estimated that AC prevented nearly 200,000 premature deaths in 2019 alone—but bad for the planet. Artificial chill already accounts for 7% of global electricity use and 3% of greenhouse-gas emissions, and if improperly disposed of, the units can leak refrigerants with more global-warming potential than carbon dioxide.
Feeling the heat, a number of scientists and startups are hoping to amp up solid-state cooling, which is currently used at a small scale for things like mini fridges, EV batteries, and some high-end gaming computers. Traditional ACs transfer heat by using a compressor and a fan to circulate a refrigerant and turn it from liquid to gas.
Solid-state systems, on the other hand, move heat through conductive materials like gadolinium and bismuth telluride—which could theoretically cool spaces and surfaces with fewer messy side effects.
The catch is whether they can match the efficiency of conventional AC. “One of the key questions that remain is why are the solid-state coolers not as efficient as typical thermodynamic cycles?” says Pramod Reddy, a professor of mechanical engineering at the University of Michigan who studies heat transfer.
Research and pilot programs are underway to test a range of approaches. Brooklyn-based Mimic Systems uses thermoelectric cooling, which passes a current through semiconductive materials to shift heat from one side to another. Its room-scale climate control system is being piloted in an apartment in Vancouver.
The German company Magnotherm is set to test its system, which relies on a magnetocaloric setup that transfers heat by magnetizing and demagnetizing materials, in a chain of supermarkets. A team in Hong Kong has announced that its elastocaloric device, whose material heats and cools as it expands and contracts, can dip below 0 °C. And the UK’s Barocal is betting on barocaloric systems, which change temperature in response to shifts in pressure.
But experts, especially in thermoelectrics, have doubts about how well any solid-state scheme can compete. For most modern HVAC systems, the coefficient of performance (COP) is 3, explains Jeff Snyder, a professor at Northwestern University who studies electrical and thermal conductivity. That essentially means the system moves three units of heat for every unit of energy that goes into it.
Thermoelectrics in particular tend to have a much lower performance at high levels of temperature change, Snyder says, which means they’re best suited for niche uses such as cooling the back of a car seat.
Mimic’s room-scale thermoelectric HVAC unit is being tested in a Vancouver apartment.
COURTESY OF MIMIC SYSTEMS, INC
Efficiency, however, isn’t everything, argues Lindsay Rasmussen, a manager at the Rocky Mountain Institute’s climate tech accelerator Third Derivative, which supports both Magnotherm and Mimic. In the US, most ACs currently in use employ a refrigerant called R410A, which has a global-warming potential more than 2,000 times that of carbon dioxide. Plus, their moving parts can make them less durable, especially compared with a solid-state model that’s less mechanically complex.
Still, a dearth of units makes it hard to answer the efficiency question. To understand how well alternatives work, says Rasmussen, researchers need to compare their long-term energy consumption with that of conventional models instead of simply looking at COP. Mimic claims, for example, that its room-scale model should match the draw of a typical AC unit over the course of a year. Elastocaloric and barocaloric systems also have promise, Rasmussen adds, but room-scale prototypes are probably two to three years away.
In the end, the likelihood that solid-state cooling could replace compressor-based AC is slim. But as the planet warms and places like India install tens of millions of new AC units over the next decade, supplanting even a small number could make a dent. “If [solid-state] could take over even a 5% market share,” Rasmussen says, “that is a really large potential impact.”
Sara Kiley Watson is a science journalist specializing in climate and sustainability. She’s based in The Hague.
