Pill-sized implant translates brain signals into movement for two people paralyzed by stroke
Cathy Hutchinson imagined picking up her coffee from the table. She thought about bringing the red bottle toward her lips and taking a drink, without any assistance. Then, for the first time since a stroke left her arms and legs paralyzed 15 years earlier, she did it.
A blue robotic arm, guided by an experimental brain implant that “read” Hutchinson’s thoughts, grasped the bottle and carried it from the table toward the 58-year-old from East Taunton. By picturing herself moving her own immobile right arm and hand, she navigated the robot arm to the right position and tipped the bottle toward her lips. Hutchinson closed her eyes and took a long, satisfied sip through a straw before placing the bottle back on the table. A smile spread across her face. Researchers who watched in rapt silence in April 2011 burst out in applause.
On Wednesday, the team, led by scientists from the US Department of Veterans Affairs in Providence and Brown University, revealed that two paralyzed patients -- Hutchinson and a 66-year-old man named Robert -- had been able to use their minds to control a robotic hand, successfully touching and grasping objects in repeated trials.
“I had feelings of hope and a great sense of independence, when drinking from a cup,” Hutchinson said in written response to reporters’ questions sent by e-mail on Monday. She answered questions by choosing letters with her eyes to spell out words, because the stroke also left her unable to speak. “This was a long term goal I had and I was elated.”
The feat, reported in the journal Nature, was part of an ongoing clinical trial of the BrainGate , a pill-sized device covered in electrodes that is implanted in the brain to record the activity of brain cells triggered by thinking. Those electrical signals are decoded by computer algorithms, and translated into the movement of a cursor on a screen or a robotic arm through the air, with the ultimate goal of restoring mobility and independence to people who have been paralyzed through spinal cord injuries, disease, or strokes.
“The smile on her face is something I and our whole research team will never forget,” said Dr. Leigh Hochberg, a researcher at the VA and Brown University and a critical care neurologist at Massachusetts General Hospital. “The progress both our participants have demonstrated is very encouraging, though there’s undoubtedly still more work to do.”
It will be years, if ever, before a device would be commercially available, and the road even to this point has been filled with unexpected turns -- exciting advances coupled with the technical complexity of the task.
The inspiring proof that neural signals could be translated into controlled, 3-D movement in a real-world environment is the product of years of research into basic neuroscience, engineering, and robotics. It’s the result of millions of dollars of private investment and federal funds. A Foxborough company, Cyberkinetics Inc., founded to commercialize the technology, was shuttered three years ago.
The same team demonstrated in 2006 that electrodes implanted in the brains of a research subject could be used to move a cursor around on a screen, open e-mail, and operate a television. Other research groups are also working on technology to bridge the devastating gap that can occur when paralysis or disease leaves people’s minds intact but their bodies unresponsive, including an external cap fitted with sensors that read the brain’s electrical activity and electrodes implanted under the skull.
In the BrainGate experiment, the small devices were implanted near an area of the brain involved in voluntary muscle movements. The two research subjects first watched the robot arm mounted on an adjacent platform perform a series of movements while imagining themselves moving their own arms in the same way. The chip in their brains measured the pattern of electrical activity from dozens of neurons, detecting what signals meant move right or left, or squeeze an object. Then, the researchers gave control of the arm to Hutchinson and Robert. With their thoughts, both participants used a robotic arm to try to repeatedly touch and grasp a succession of pink foam balls affixed to cones. In a separate trial, the researchers gave Hutchinson the opportunity to serve herself the drink. She succeeded in four out of six attempts, over a total of eight and a half minutes.
Outside scientists said the experiments were an exciting advance, and added it was significant that both patients had their injuries for some time because it shows the necessary brain circuits remained functional. Hutchinson had been implanted with the BrainGate device for five years, also suggesting that the technology could work over a long span. Robert had suffered a stroke five and a half years before the study and had the implant for five months.
“You could imagine someone who had an amputation or a spinal cord injury 5 or 10 years before would not be eligible ... but these patients show the competency still remains,” said Story Landis, director of the National Institute of Neurological Disorders and Stroke, which began funding the foundational research by Brown University neuroscientist John Donoghue in 1986. The current study was supported by the National Institutes of Health and the Department of Veterans Affairs, and Landis said she thought the technology might have important applications for veterans wounded in Iraq or Afghanistan, with the possibility of one day providing a precise way to control prosthetic limbs.
Still, challenges remain. The biggest problem now facing the field, which includes technologies that use neural implants and those that detect electrical activity using external sensors, is the need for consistency, said Dr. Jonathan Wolpaw, chief of the laboratory of neural injury and repair at the Wadsworth Center at the New York State Department of Health.
“The dominating feature for the field is that all these approaches face the same, very big issue of reliability,” Wolpaw said in an e-mail. “None of these methods is anywhere near as reliable and consistent as it would need to be to be of use in everyday life.”
For example, Hutchinson successfully touched the pink foam balls within the allotted time about half the time with one robotic arm and a little over two-thirds of the time with another type of robot arm. Overall, she successfully grasped the objects less than half the time. Robert touched the foam balls in 96 percent of the trials, and grasped them successfully 62 percent of the time.
Still, for Hutchinson, the thrill of seeing her thoughts seamlessly translated into movement made her feel “ecstatic.” She said she dreams of one day having the ability to control her legs and hopes to one day be able to resume her hobbies of gardening and cooking.Carolyn Y. Johnson can be reached at firstname.lastname@example.org. Follow her on Twitter @carolynyjohnson.
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