June 12, 2013
Brain-Computer Interface Allows Patients To Control Robotic Limbs
redOrbit Staff & Wire Reports - Your Universe Online
Electrodes placed on or inside the brain allow patients to interact with computers or control robotic limbs by merely thinking about how to execute those actions, University of Washington researchers reported on Tuesday.
The technology could improve the quality of life for people who are paralyzed or lack the ability to speak due to stroke or neurodegenerative disease by allowing them to control a robotic arm or a prosthetic limb in a way that feels like second nature, the researchers said.
The study showed that when humans use a technology known as brain-computer interface, the brain behaves much as it does when completing simple motor skills such as kicking a ball, typing or waving a hand.
“What we´re seeing is that practice makes perfect with these tasks,” said senior researcher Rajesh Rao, a UW professor of computer science and engineering.
“There´s a lot of engagement of the brain´s cognitive resources at the very beginning, but as you get better at the task, those resources aren´t needed anymore and the brain is freed up,” he told UW News.
The researchers worked with seven people with severe epilepsy who were hospitalized for a monitoring procedure that tried to identify where in the brain seizures originate.
Doctors cut through the scalp, drilled into the skull and placed a thin sheet of electrodes directly atop the patients´ brain. As the doctors watched for seizure signals, the UW researchers conducted their study.
The patients were asked to move a cursor on a computer screen by using only their thoughts to control the cursor´s movement. Electrodes on their brains detected the signals directing the cursor to move, sending them to an amplifier and then a laptop to be analyzed.
Within 40 milliseconds, the computer calculated the intent transmitted through the signal, and made the corresponding movement of the cursor on the screen.
When patients began the task, a flurry of brain activity was centered in the prefrontal cortex, an area associated with learning a new skill, the study revealed.
However, often in as little as 10 minutes frontal brain activity lessened, and the brain signals shifted to patterns similar to those seen during more automatic actions.
“Now we have a brain marker that shows a patient has actually learned a task,” said Jeffrey Ojemann, a professor of neurological surgery who worked on the study. “Once the signal has turned off, you can assume the person has learned it.”
Previous studies have demonstrated success in using brain-computer interfaces in monkeys and humans, but the current study is the first to clearly map the neurological signals throughout the brain.
The researchers said they were surprised at how many parts of the brain were involved.
“We now have a larger-scale view of what´s happening in the brain of a subject as he or she is learning a task,” Rao said. “The surprising result is that even though only a very localized population of cells is used in the brain-computer interface, the brain recruits many other areas that aren´t directly involved to get the job done.”
Several types of brain-computer interfaces are in various stages of testing and development, the least invasive of which is a device placed on a person´s head that can detect weak electrical signatures of brain activity.
Basic gaming products are commercially available, but the technology isn´t yet reliable because signals from eye blinking and other muscle movements interfere too much.
A more invasive alternative is to surgically place electrodes inside the brain tissue itself to record the activity of individual neurons. Researchers at Brown University demonstrated such a procedure last May, showing that a woman was able to move a robotic arm with her brain; and researchers from the University of Pittsburgh also demonstrated this past December that a woman was able to eat chocolate by moving a robotic limb with signals from the brain.
The UW researchers tested electrodes on the surface of the brain, underneath the skull, to allow them to record brain signals at higher frequencies and with less interference than measurements from the scalp.
In the future, a wireless device could be built to remain inside a person´s head for a longer time to be able to control computer cursors or robotic limbs at home.
“This is one push as to how we can improve the devices and make them more useful to people,” said study researcher Jeremiah Wander, a doctoral student in bioengineering.
“If we have an understanding of how someone learns to use these devices, we can build them to respond accordingly.” The study is published online June 10 in the Proceedings of the National Academy of Sciences (PNAS).