Brain Implant Lets ALS Patient Work and Talk at 56 WPM

Casey Harrell hasn't let ALS silence him, thanks to a brain implant that lets him talk, text, and keep his job advocating for climate action.

The 48-year-old Oakland resident was diagnosed with amyotrophic lateral sclerosis six years ago, a motor neuron disease that gradually steals the body's ability to move and speak. But in 2023, doctors implanted 256 tiny electrodes in the speech motor cortex of his brain, connecting them to recording devices through titanium pedestals on his skull.

The results changed everything. Harrell can now communicate at an average speed of 56 words per minute by simply thinking what he wants to say.

The brain-computer interface translates his neural activity into text on a screen, allowing him to operate his computer, send messages, and earn money to support his family. The system even includes a text-to-speech feature using a synthesized version of his voice from before his diagnosis.

"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."

After about 40 weeks of training with researchers at the University of California, Davis, Harrell began using the device independently at home. He's been using it ever since.

The results published in Nature Medicine reveal just how transformative the technology has become. Over nearly 23 months, Harrell used the brain implant on 364 out of 397 days, communicating 183,060 sentences with 92% decoded at least mostly correctly.

"The quality of the speech decoding is quite remarkable," says Christian Herff, a computational neuroscientist at Maastricht University in the Netherlands who wasn't involved in the study. The information transfer rate is "several orders of magnitude faster" than previous attempts to deploy brain-computer interfaces in patients' homes.

The Ripple Effect

This study represents the longest-running speech communication anyone has achieved with such an implant, according to co-author Sergey Stavisky, a neuroscientist at UC Davis. Previous brain-computer interfaces tested at home showed limited efficiency, and more advanced devices only worked in laboratory settings.

Now these devices are becoming practical medical tools instead of just research experiments. The implant also picks up neural signals for hand movements, helping Harrell control a computer mouse.

The research team even built in a privacy mode, allowing Harrell to stop data transmission to researchers 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," explains co-author Nicholas Card, a neural engineer at UC Davis.

For Harrell, the technology is "nothing short of revolutionary," giving him back his voice and his independence when he needs them most.