Background

Casey Harrell has ALS. In July 2023 a UC Davis team implanted four arrays of 64 microelectrodes in his speech motor cortex as part of the BrainGate2 trial. Software translates the recorded activity into phonemes and then words, which a computer voice speaks aloud. The team, co-led by David Brandman and Sergey Stavisky, published earlier results from his implant in the New England Journal of Medicine in 2024.

Home use

Over the 22.6 months after surgery, Harrell used the system at home for more than 3,800 hours without researchers present, results published in Nature Medicine on 15 June 2026. Its vocabulary reached 125,000 words at 97.5 per cent accuracy, and Harrell rated 92 per cent of the sentences he produced at home as accurate or mostly correct. A cursor decoder lets him use a computer for messaging, email, web browsing and his work as an environmental activist. His care partner now connects and disconnects the device, and the system includes a privacy mode. Stavisky has called him “the first power user of a speech BCI.”

Why it matters

Sustained home use without a research team on hand is the setting in which implanted speech devices will have to prove their value. Harrell’s case is one patient, and outcomes may not transfer to others as their disease progresses. Brandman is also lead principal investigator of Paradromics’ Connect-One trial, which is testing speech restoration with the company’s Connexus implant.

Coverage on InsideBCI

• 16 June 2026: A man with ALS has used his speech brain implant at home for nearly two years, mostly on his own
• 17 June 2026: A Michigan woman with motor neuron disease has received the first Paradromics Connexus brain implant
• 23 September 2026: Neuralink discloses direct thought-to-audio speech decoding in ALS participant Terry, the VOICE trial’s third implantee