Brain Implant Helps ALS Patient Work and Connect at Home

Casey Harrell can text his friends, email his coworkers, and keep doing his climate advocacy job, all thanks to a brain implant that reads his thoughts and turns them into words on a screen.

The 48-year-old from Oakland, California, was diagnosed with ALS six years ago. The disease gradually took away his ability to speak and move. But in 2023, researchers at UC Davis implanted 256 tiny electrodes in the part of his brain that controls speech.

The device translates his brain's signals into text at 56 words per minute. That's faster than many people type on their phones. Harrell used it at home on 364 out of 397 days over nearly two years, sending more than 183,000 sentences.

"This has allowed me to keep working and earn money and insurance for my family," Harrell says. "This is reconnecting me with friends and family who are too shy or too afraid to come over and not be able to understand me."

The system also includes a text-to-speech feature that reads his sentences aloud using a computerized version of his own voice from before his diagnosis. He can even control a computer mouse by thinking about moving his hand.

The Ripple Effect

This marks a turning point for brain-computer interfaces. Previous home tests showed limited results, and more advanced devices stayed confined to labs. Christian Herff, a neuroscientist at Maastricht University who wasn't involved in the study, says these devices are "really becoming a medical device instead of a research tool."

The UC Davis team trained Harrell and his caregivers to operate the system independently after about 40 weeks. He's still using it today. The researchers also built in a privacy mode that lets Harrell stop sending data to the team whenever he wants.

"We wanted to add this privacy feature to set a good example for what a speech BCI might include in future forms," says study co-author Nicholas Card.

For people living with paralysis, this technology offers something profound: the ability to maintain their independence, support their families, and stay connected to the people they love.