The Wall Street Journal
written by Gautam Naik
Wednesday May 16, 2012
Two paralyzed patients used their thoughts to direct a robotic arm to grasp objects, a striking advance in the quest to restore some function to people with paralyzed limbs.
One of the patients, a 58-year-old Massachusetts woman named Cathy Hutchinson, used the technique to bring a coffee container to her lips for the first time in 15 years. Ms. Hutchinson was rendered immobile by a stroke she suffered while tending her garden in 1996.
She and another patient, 66-year-old Robert Veillette of Connecticut, who also can't speak or move his limbs, manipulated the robotic arm by imagining the movements of their own arms. Mr. Veillette, a former managing editor of the Republican-American newspaper in Waterbury, Conn., became paralyzed after suffering a stroke in 2006.
The experiments are part of a continuing clinical trial of a "neural interface" system known as BrainGate, initially developed at Brown University. The system detects electrical signals in the brain and uses them to control an external device—in this case, a robotic arm. Details were published in the journal Nature.
The patients' feats are a far cry from the complex movements of able-bodied people. But "what's impressive about this study is that it shows how neural-interface technology can be used for activities of daily living," said Andrew Jackson, an expert on movement neuroscience at Newcastle University in England, who wasn't involved in the experiment.
While it is a big step, the technique is years from practical use for people with paralysis or limb loss. The experiment was done under controlled circumstances in the patients' homes, where a technician was present to help with the tricky calibration of the robotic arm.
The study was a collaboration of researchers at Brown, the Department of Veterans Affairs, Massachusetts General Hospital, Harvard Medical School and the German Aerospace Center. It was funded by the National Institutes of Health, the Department of Veterans Affairs and other groups. BrainGate patent holders include Brown, Emory University and Black Rock Microsystems, a technology company.
Bolstered by decades of basic research into how the brain controls movement, the field has notched some milestones. A 2006 paper described how a patient paralyzed by a spinal-cord injury used BrainGate to move a computer cursor. Two years later, other scientists reported that monkeys with small brain sensors had used their thoughts to control a mechanical arm and feed themselves.
When humans perform an action, electrical signals originate in the brain, travel through the spinal cord and instruct muscles to move. A stroke or other trauma can disrupt the nerve pathways and cause paralysis. A neural-interface system is designed to sidestep nerve injuries and let the brain communicate directly with another device.
Both patients in the Nature study had suffered a brainstem stroke, which afflicts the area between the brain and the spinal cord. As a result, both Mr. Veillette and Ms. Hutchinson have "locked-in syndrome," the inability to move the limbs or speak.
For the study, a pill-size device with 96 tiny electrodes was implanted in the motor cortex, an area of the brain that controls voluntary movement. Scientists then moved a robotic arm connected by computers to the electrodes in the patient's brain. With each movement, the patient was asked to simultaneously try to move a paralyzed arm in the same direction. That caused certain neurons to fire in a specific pattern, and those data were recorded.
The patients were then given direct control of the robotic arm. When they imagined a movement, such as clenching their fingers around a coffee cup, that sent an electrical signal from their brains to the computers, which recognized the brain's intention from the recordings and directed the robot arm to clench its fingers around the cup.
"The desire and intention to move still exists. We're merely recording that intention," said Leigh Hochberg, a neurologist and the lead investigator in the trial, who holds appointments at Brown, Massachusetts General Hospital and other institutions.
Both patients used the robotic arm to grasp foam objects. In addition, Ms. Hutchinson used it to pick up a bottle of coffee and bring it to her lips. She then drank through a straw and returned the bottle to the table.
The researchers found they had to record signals from only a few dozen neurons.
"There's clearly a great amount of redundancy in the motor cortex," said John Donoghue, the Brown neuroscientist who pioneered BrainGate more than a decade ago and is a senior author of the study.
Scientists' long-term goals are to do away with invasive brain implants and, still more ambitious, connect the brain not to a cumbersome robotic arm but to the patient's own paralyzed limbs. Progress is being made in both areas.
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