Device for the Paralyzed Turns Thinking to Doing
Harnessing the electrical echoes of thought, researchers have developed a way for people to control a computer cursor simply by thinking about it.
The device, which so far has been tested successfully on four people, does not require implants, surgery or any other invasive medical procedure, the researchers reported Monday. Previous efforts required electrodes wired directly into brain cells.
Instead, scientists at the New York State Department of Health and the State University of New York designed a system to monitor the faint electricity that naturally radiates from every brain and then created special computer software to translate those reflections of thought into direct action.
The research, which was made public in the Proceedings of the National Academy of Sciences, appears to offer a means for people paralyzed by stroke, spinal cord injury or amyotrophic lateral sclerosis (Lou Gehrig’s disease) to operate computers or prosthetic devices by imagining the movement.
“It is an impressive achievement,” said John Donoghue, a senior neuroscientist at Brown University who was not involved in the research project. “Such a device has great potential to improve the lives of paralyzed individuals.”
Scientists have long sought to bridge the gulf of damaged nerves between the brain cells that control movement or speech and the muscles those cells seek to animate.
By developing a link between mind and computer, they hope that patients who are unable to move or speak can resume their interaction with the world around them. Researchers estimate that there are more than half a million “locked-in” patients -- people who, due to disease or injury, are unable to control their muscles enough to activate any communication device.
Experimental implants developed by independent research groups at Brown, SUNY and Duke University have enabled monkeys to control cursors and robotic limbs through the power of thought, and even operate devices at a distance.
Starting in 1999, several paralyzed patients in Atlanta underwent experimental surgery for brain implants that allowed them rudimentary control of a computer.
Donoghue, who is also chief scientific officer of Cyberkinetics Inc. in Foxborough, Mass., is conducting clinical trials of an implant the size of an M&M; that could allow people to send e-mail, surf the Web and command other computer resources simply by thinking about them.
The new brain-computer interface, however, eliminates the necessity for surgery.
The researchers used a skein of 64 electrodes in a cap placed on the scalp to eavesdrop on the wasted energy of thought, tapping into the patterns of neural electricity that normally dissipate in the immediate vicinity of the skull.
“Using signals recorded from the scalp, people can learn to gain control of movement,” said clinical neurologist Jonathan R. Wolpaw, who spent the last decade developing the experimental system with psychologist Dennis J. McFarland. “They can achieve impressively accurate and rapid control. It may not be necessary to stick something into the brain.”
In order to capture the proper neural signals, the researchers needed only to position the electrodes around the general location of the brain’s sensory motor cortex. The computer software was designed to adapt to the patient’s increasing ability to move the cursor.
So far, three men and a woman have tested the system. Two of the volunteers had spinal cord injuries that confined them to wheelchairs. They appeared to master the technique more quickly than the others, Wolpaw said.
Even so, it is no panacea, Wolpaw cautioned.
The device required considerable practice, he said, and for the foreseeable future, the close supervision of an experienced scientist.
The volunteers needed more than five weeks of regular lessons to master the basics of the technique, then hours more in practice sessions to refine their new ability.
The team has wasted no time in refining the technique. Collaborating with a research group in Germany, they have enlisted additional patients who are being trained in its use.
“Everyone is rooting for the noninvasive stuff to be as useful as possible because that is what would be most helpful to most people,” said John Chapin, director of the SUNY center for neurorobotics and neuroengineering. “The kind of patient who would benefit from invasive [implants] is a very, very sick patient.”
In its current state, Chapin said, the new noninvasive technique enabled movement in just two dimensions -- up and down and side to side -- certainly adequate for a computer cursor but short of the full range of movement required by a robotic arm or prosthetic leg.
“The future,” Chapin said, “is gong to be some combination of the two.”
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