Paralyzed woman’s thoughts guide robot arm
U. PITTSBURGH (US) — A woman with longstanding quadriplegia maneuvered a mind-controlled, human-like robot arm in seven dimensions, using it to feed herself dark chocolate and high-five someone.
In a study published in the online version of The Lancet, the researchers describe the brain-computer interface (BCI) technology and training programs that allowed Jan Scheuermann, 53, of Whitehall Borough in Pittsburgh, Pennsylvania to intentionally move an arm, turn and bend a wrist, and close a hand for the first time in nine years.
Within a week, Jan Scheuermann, who has quadriplegia, could reach in and out, left and right, and up and down with the arm, which she named Hector, giving her 3-dimensional control that had her high-fiving with the researchers. View larger. (Credit: UPMC)
Less than a year after she told the research team, “I’m going to feed myself chocolate before this is over,” Scheuermann savored its taste and announced as they applauded her feat, “One small nibble for a woman, one giant bite for BCI.”
“This is a spectacular leap toward greater function and independence for people who are unable to move their own arms,” agrees senior investigator Andrew B. Schwartz, professor in the department of neurobiology at the University of Pittsburgh School of Medicine.
“This technology, which interprets brain signals to guide a robot arm, has enormous potential that we are continuing to explore. Our study has shown us that it is technically feasible to restore ability; the participants have told us that BCI gives them hope for the future.”
“Hook me up”
In 1996, Scheuermann was a 36-year-old mother of two young children, running a successful business planning parties with murder-mystery themes and living in California when one day she noticed her legs seemed to drag behind her. Within two years, her legs and arms progressively weakened to the point that she required a wheelchair, as well as an attendant to assist her with dressing, eating, bathing, and other day-to-day activities.
After returning home to Pittsburgh in 1998 for support from her extended family, she was diagnosed with spinocerebellar degeneration, in which the connections between the brain and muscles slowly, and inexplicably, deteriorate.
“Now I can’t move my arms and legs at all. I can’t even shrug my shoulders,” she says. “But I have come to the conclusion that worrying about something is experiencing it twice. I try to dwell on the good things that I have.”
A friend pointed out an October 2011 video about another University of Pittsburgh/UPMC BCI research study in which Tim Hemmes, a Butler, Pennsylvania, man who sustained a spinal cord injury that left him with quadriplegia, moved objects on a computer screen and ultimately reached out with a robot arm to touch his girlfriend.
“Wow, it’s so neat that he can do that,” Scheuermann thought as she watched him. “I wish I could do something like that.” She had her attendant call the trial coordinator immediately, and said, “I’m a quadriplegic. Hook me up, sign me up! I want to do that!”
“This is really going to work”
On February 10, 2012, after screening tests to confirm that she was eligible for the study, co-investigator and UPMC neurosurgeon Elizabeth Tyler-Kabara, assistant professor in the department of neurological surgery at Pitt School of Medicine, placed two quarter-inch square electrode grids with 96 tiny contact points each in the regions of Scheuermann’s brain that would normally control right arm and hand movement.
“Prior to surgery, we conducted functional imaging tests of the brain to determine exactly where to put the two grids,” she says. “Then we used imaging technology in the operating room to guide placement of the grids, which have points that penetrate the brain’s surface by about one-sixteenth of an inch.”
The electrode points pick up signals from individual neurons and computer algorithms are used to identify the firing patterns associated with particular observed or imagined movements, such as raising or lowering the arm, or turning the wrist, explains lead investigator Jennifer Collinger, assistant professor in the department of physical medicine and rehabilitation (PM&R), and research scientist for the VA Pittsburgh Healthcare System.
That intent to move is then translated into actual movement of the robot arm, which was developed by Johns Hopkins University’s Applied Physics Lab.
Two days after the operation, the team hooked up the two terminals that protrude from Scheuermann’s skull to the computer. “We could actually see the neurons fire on the computer screen when she thought about closing her hand,” Collinger says. “When she stopped, they stopped firing. So we thought, ‘This is really going to work.'”
Within a week, Scheuermann could reach in and out, left and right, and up and down with the arm, which she named Hector, giving her 3-dimensional control that had her high-fiving with the researchers. “What we did in the first week they thought we’d be stuck on for a month,” she notes.
Before three months had passed, she also could flex the wrist back and forth, move it from side to side, and rotate it clockwise and counter-clockwise, as well as grip objects, adding up to what scientists call 7D control.
From code to motion
In a study task called the Action Research Arm Test, Scheuermann guided the arm from a position four inches above a table to pick up blocks and tubes of different sizes, a ball, and a stone and put them down on a nearby tray. She also picked up cones from one base to restack them on another a foot away, another task requiring grasping, transporting, and positioning of objects with precision.
“Our findings indicate that by a variety of measures, she was able to improve her performance consistently over many days,” Schwartz explains.
“The training methods and algorithms that we used in monkey models of this technology also worked for Jan, suggesting that it’s possible for people with long-term paralysis to recover natural, intuitive command signals to orient a prosthetic hand and arm to allow meaningful interaction with the environment.”
In a separate study, researchers also continue to study BCI technology that uses an electrocortigraphy (ECoG) grid, which sits on the surface of the brain rather than slightly penetrates the tissue as in the case of the grids used for Scheuermann.
In both studies, “we’re recording electrical activity in the brain, and the goal is to try to decode what that activity means and then use that code to control an arm,” says senior investigator Michael Boninger, professor and chair of PM&R, and director of UPMC Rehabilitation Institute.
“We are learning so much about how the brain controls motor activity, thanks to the hard work and dedication of our trial participants. Perhaps in five to ten years, we will have a device that can be used in the day-to-day lives of people who are not able to use their own arms.”
The next step for BCI technology will likely use a two-way electrode system that can not only capture the intention to move, but in addition, will stimulate the brain to generate sensation, potentially allowing a user to adjust grip strength to firmly grasp a doorknob or gently cradle an egg.
After that, “we’re hoping this can become a fully implanted, wireless system that people can actually use in their homes without our supervision,” Collinger says. “It might even be possible to combine brain control with a device that directly stimulates muscles to restore movement of the individual’s own limb.”
For now, Scheuermann is expected to continue to put the BCI technology through its paces for two more months, and then the implants will be removed in another operation.
“This is the ride of my life,” she says. “This is the rollercoaster. This is skydiving. It’s just fabulous, and I’m enjoying every second of it.”
The Defense Advanced Research Projects Agency, National Institutes of Health, the US Department of Veteran’s Affairs, the UPMC Rehabilitation Institute, and the University of Pittsburgh Clinical and Translational Science Institute fund the BCI projects.
For more information about participating in the trials, call 412-383-1355.
Source: University of Pittsburgh