Researchers at the University of Pittsburgh School of Medicine and its affiliated medical center placed an electrode array on top of a paralyzed man's brain to allow him to move a robotic arm by thinking about it. It's being hailed as an important step in helping him — and others — achieve independence.
This month in the journal PLoS One, the scientists describe how 30-year-old Tim Hemmes, who was injured in a motorcycle accident seven years ago, was able to not only move his robotic arm to touch a friend's hand, but also control movements of a character on a computer screen in three dimensions using just his thoughts.
Hemmes has been unable to move his body below the shoulders. The scientists used brain-computer interface technology that interpreted his thoughts into computer algorithms and then further into the intended movement of both the computer cursor and later the robotic arm. The arm was developed by Johns Hopkins University's Applied Physics Laboratory.
Hemmes has been working with the program for some time. In October 2011, researchers issued a statement after he high-fived his girlfriend for the first time.
A similiar milestone was noted in the research published in the journal. "When Tim reached out to high-five me with the robotic arm, we knew this technology had the potential to help people who cannot move their own arms achieve greater independence," said Wei Wang, Ph.D. and an assistant professor in the Department of Physical Medicine and Rehabilitation at Pitt School of Medicine, in a statement accompanying the new announcement.
The implantation occurred weeks after the team used functional magnetic resonance imaging (fMRI) of his brain while he watched videos of arm movement. Using the information they got from that, they placed a grid of 28 recording electrodes — a unit about the size of a postage stamp — on the part of the brain identified by the imaging as being in control of right arm and hand movement.
"For 12 days at his home and nine days in the research lab, Mr. Hemmes began the testing protocol by watching a virtual arm move, which triggered neural signals that were sensed by the electrodes," the statement said. "Distinct signal patterns for particular observed movements were used to guide the up-and-down motion of a ball on the computer screen. Soon after mastering the movement of the ball in two dimensions, namely up/down and right/left, he was able to also move it in/out with accuracy on a three-dimensional display."
Wang said they initially provided the equivalent of "training wheels" by limiting how far off course the ball could wander. They gradually lifted those restrictions so he eventually was in complete control of it using just his brain.
It's not the first time researchers have tested electrode arrays implanted in the brain to help those who are paralyzed. ScienceNow reported six years ago on the use of an electrode array for that purpose in a human. Single electrodes had been placed in human brains before that, while more sophisticated arrays of electrodes were being tested in monkeys.
Nature carried a report last May on two subjects who had suffered brainstem strokes, leaving them with no motion below the head, who were able to operate a robotic arm using thoughts, courtesy of electrode arrays and other technology. One, a woman, was able to sip from a straw. And two-thirds of the time, reported the researchers, led by Brown University and the Veterans Administration, they were able to do the simple task they were attempting through their thoughts.
The electrode arrays are often described by their size, compared to baby aspirins and postage stamps and dimes, for example.
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