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Jun 16, 20262
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ALS Patient Becomes First 'Power User' of Brain Implant, Using Device for Over 3,800 Hours
Casey Harrell, a 45-year-old man with ALS, has become the first "power user" of a brain-computer interface implant, using it for over 3,800 hours in nearly three years. The device, which decodes neural signals from his speech motor cortex, enables him to communicate with 97.5% accuracy across 125,000 words and perform daily tasks including reading to his daughter and working independently.
Quick Facts
Who
Casey Harrell
What
Brain-computer interface implant placed in patient's brain
When
July 2023 - surgery date
Where
University of California, Davis
- Brain-computer interface implant placed in patient's brain
- Four arrays of 64 electrodes each implanted
- Electrodes wired to two external pedestal connection points
- Neural signals decoded into phonemes then words
- Device used for communication, web browsing, and employment
Casey Harrell, a 45-year-old man with amyotrophic lateral sclerosis (ALS), has become the first "power user" of a brain-computer interface (BCI) implant, demonstrating the technology's potential for long-term independent use by paralyzed patients. In July 2023, surgeons implanted four arrays of 64 electrodes each into Harrell's brain, with each pair wired to external "pedestal" connection points on his skull. The system decodes neural activity from his speech motor cortex—the region responsible for movements that produce speech—converting brain signals into phonemes and then into spoken words with 97.5% accuracy across a vocabulary of 125,000 words.
Within the first 22.6 months after implantation, Harrell used the device for more than 3,800 hours at home without researchers present, a milestone that underscores the technology's durability and practical viability. The device has allowed him to perform multiple daily tasks: he speaks with friends and family, reads to his young daughter, surfs the web, and performs his job largely independently after being connected to the system by a carer. On the first day of use in August 2023, the device achieved 99.6% accuracy with a 50-word vocabulary, which was later expanded dramatically without losing functionality.
Harrell credits the technology with fundamentally changing his outlook. "Living with a disease like ALS, you are supposed to have diminished dreams. I do not," he told MIT Technology Review, describing the implant as "truly revolutionary." He emphasized that while any single improvement would be transformative, having multiple capabilities—communication, web access, and employment—combined represents an unprecedented advancement in his quality of life.
The research team, led by neuroengineer David Brandman at the University of California, Davis, has continued to refine the system. Team member Sergey Stavisky describes Harrell as "the first power user of a speech BCI," marking a significant milestone in brain-computer interface development. The team has automated more of the device's operation, reducing dependence on researchers for daily connection and disconnection, and plans to add further enhancements to the technology. This progress addresses a longstanding concern in BCI research: the formation of scar tissue around electrodes that can degrade signal quality over time—a problem that has not materialized in Harrell's case.
Why This Matters
This breakthrough demonstrates that brain-computer interfaces can provide stable, long-term independence for paralyzed patients in real-world settings without constant researcher supervision. For ALS patients facing progressive paralysis, this technology offers a pathway to maintain communication, employment, and quality of life—addressing one of the most debilitating aspects of the disease. The successful 3,800+ hours of unsupervised use also validates the durability of the implant and reduces concerns about electrode degradation, setting a precedent for wider clinical adoption.