UC Davis brain‑computer implant enables ALS patient to communicate independently

A brain‑computer interface (BCI) developed at the University of California, Davis, in collaboration with Brown University and Mass General Brigham Neuroscience Institute, has allowed 47‑year‑old Casey Harrell, who has severe amyotrophic lateral sclerosis (ALS), to communicate independently at home. The implant places four micro‑electrode arrays in the left precentral gyrus, decoding neural activity linked to attempted speech and movement into text. Over nearly two years, Harrell used the system for more than 3,800 hours, producing over 183,000 sentences and close to 2 million words at an average speed of 56 words per minute, with 99% word accuracy in testing and 92% of sentences rated as accurate. The decoded text is spoken by a digital voice that resembles Harrell’s pre‑ALS voice, enabling him to send emails, browse the internet, work, and interact with family without researcher assistance. The results, published in Nature Medicine, represent a major step toward practical, at‑home assistive technology for people with severe speech and motor impairments.