Casey Harrell, who has ALS and is paralyzed, has used a brain-computer interface since July 2023 to communicate, browse the web, work as a climate activist, and read to his daughter. Researchers at UC Davis have tuned the system’s accuracy and added features such as privacy mode and a “profanity filter,” while the device decodes speech-related brain activity into phonemes and plays output in a cloned version of his voice.
BCIs vary widely by design and risk. Harrell’s system uses electrodes implanted in the brain and docking ports that connect to a computer, while other systems are wireless, rest on the brain’s surface, or use electrode caps. More invasive implants tend to capture stronger neural signals, but they also carry higher surgical risks.
Trial activity has accelerated across academic and commercial efforts. A 2024 review found 21 research groups had tested BCIs in 67 volunteers between 1998 and the end of 2023, and BCI researcher Mariska Vansteensel now estimates that around 150 people have received brain electrodes. Neuralink, Synchron, Neuracle, Precision Neuroscience, BrainGate, and other groups are testing devices for speech, cursor control, mobility, and broader independence.
The field remains experimental, with open questions about durability and who benefits most. Some systems that initially helped people with ALS, including a person who was completely locked in, later stopped working for reasons scientists do not yet understand.
