I’ll just copy the Science News headline here and say “Brain implants turn imagined handwriting into text on a screen“:
A 65-year-old man had two grids of tiny electrodes implanted on the surface of his brain. The electrodes read electrical activity in the part of the brain that controls hand and finger movements. Although the man was paralyzed from the neck down, he imagined writing letters softly with his hand. With an algorithm, researchers then figured out the neural patterns that went with each imagined letter and transformed those patterns into text on a screen.
From his brain activity alone, the participant produced 90 characters, or 15 words, per minute, Krishna Shenoy, a Howard Hughes Medical Institute investigator at Stanford University, and colleagues report May 12 in Nature. That’s about as fast as the average typing rate of people around the participant’s age on smartphones.
The thought-to-text system worked even long after the injury. “The big surprise is that even years and years after spinal cord injury, where you haven’t been able to use your hands or fingers, we can still listen in on that electrical activity. It’s still very active,” Shenoy says.
You can read the experiment in Nature here.