A woman known as Patient S3, who is paralyzed from her neck down and cannot speak, has just reached the 1,000-day anniversary with a brain-computer interface called BrainGate, and researchers are reporting in the Journal of Neural Engineering that the device is still effective.
"This proof of concept--that after 1,000 days a woman who has no functional use of her limbs and is unable to speak can reliably control a cursor on a computer screen using only the intended movement of her hand--is an important step for the field," said Leigh Hochberg, associate professor of engineering at Brown University and a visiting associate professor of neurology at Harvard University, in a news release.
During a five-day period surrounding the 1,000-day mark, the patient performed two point-and-click tasks a day with more than 90 percent accuracy by simply thinking about her hand moving the cursor.
The investigational BrainGate system employs a silicon electrode array roughly the size of a baby aspirin to read neural signals directly within brain tissue that control movement. Under development since 2002, it remains in pilot clinical trials at Massachusetts General Hospital, with S3's milestone being that she is the first to show almost three years of efficacy, though it was somewhat reduced since being implanted in 2008.
"None of us will be fully satisfied with an intracortical recording device until it provides decades of useful signals," Hochberg adds. "Nevertheless, I'm hopeful that the progress made in neural interface systems will someday be able to provide improved communication, mobility, and independence for people with locked-in syndrome or other forms of paralysis."
The device was first implanted in a human in 2004. Matthew Nagle, who was paralyzed from the neck down after being stabbed, used the system to successfully control a mouse cursor for the year he had the implant.