UC Davis researchers say an implanted brain-computer interface has allowed Casey Harrell, an ALS patient who cannot speak, to synthesize sentences from brain activity with 99% accuracy in controlled tests and about 92% accuracy in everyday use. The Register reports that the system has remained usable at home since 2023, helping Harrell communicate naturally, control a computer, and return to full-time work without researchers needing to supervise each session. The Register reports: A team of scientists from the University of California, Davis, published a paper Monday detailing a years-long study of a brain computer interface (BCI) system implanted in a patient with amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig's disease), which destroys motor neurons and causes loss of motor control and eventual paralysis. According to the team, their patient, Casey Harrell, has been living with BCI implants since 2023 that are still working today, giving him the ability not only to control a computer cursor with his thoughts, but also to speak. [...] Davis neurosurgeon David Brandman, co-principal investigator and co-senior author of the paper published Monday, as well as the surgeon who placed Harrell's implant, described the results his team published as the crossing of a threshold in BCI technology: Not only has Harrell's implant been working well with daily use since 2023, but it's also incredibly accurate.
In controlled tests, the system managed to synthesize sentences from Harrell's brain activity with 99 percent accuracy; outside of the lab in daily use, Harrell still assessed it as being accurate 92 percent of the time. "The key thing to me is that it's enabling everyday communication for a guy who wants to talk but can't," Brandman told The Register in an interview. "Despite being paralyzed [Harrell] has gone back to work full time and has meaningful conversations with his daughter who's never heard the sound of his voice."
Prior work in the BCI space, Brandman told us, has either required researchers to be in a patient's home whenever they're using the tech, or for the patient to come to the researchers. That's not the case here, with the system allowing Harrell's home care team to hook him up to the system themselves, enabling him to use the device for more than 3,800 hours in the past few years. Based on the time the study was filed (It published Monday but went into peer review in July 2025) that would mean Harrell was using the device for more than five hours a day, on average. "It is a life that is more full of dynamic action and with friends and family, with colleagues, and it is something that allows me to communicate more in my natural way of communicating than any other technology that I have experienced," Harrell told UC Davis via his BCI system.
In controlled tests, the system managed to synthesize sentences from Harrell's brain activity with 99 percent accuracy; outside of the lab in daily use, Harrell still assessed it as being accurate 92 percent of the time. "The key thing to me is that it's enabling everyday communication for a guy who wants to talk but can't," Brandman told The Register in an interview. "Despite being paralyzed [Harrell] has gone back to work full time and has meaningful conversations with his daughter who's never heard the sound of his voice."
Prior work in the BCI space, Brandman told us, has either required researchers to be in a patient's home whenever they're using the tech, or for the patient to come to the researchers. That's not the case here, with the system allowing Harrell's home care team to hook him up to the system themselves, enabling him to use the device for more than 3,800 hours in the past few years. Based on the time the study was filed (It published Monday but went into peer review in July 2025) that would mean Harrell was using the device for more than five hours a day, on average. "It is a life that is more full of dynamic action and with friends and family, with colleagues, and it is something that allows me to communicate more in my natural way of communicating than any other technology that I have experienced," Harrell told UC Davis via his BCI system.
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