New Breakthrough in Prosthetics: Brain Signals Can Control Individual Finger Movement

February 23, 2016 | Reece Alvarez

Man wears prosthetic arms with jointed fingers as researcher looks on.
Photo credit: Johns Hopkins University Applied Physics Laboratory

Researchers at Johns Hopkins University in Baltimore believe they have conducted the first experiment to prove a person can control individual fingers on a prosthetic arm using electrical signals from brain implants.

“We believe this is the first time a person using a mind-controlled prosthesis has immediately performed individual digit movements without extensive training,” said senior author Nathan Crone, M.D., professor of neurology at the Johns Hopkins University School of Medicine in a press release. “This technology goes beyond available prostheses, in which the artificial digits, or fingers, moved as a single unit to make a grabbing motion, like one used to grip a tennis ball.”

Physicians and biomedical engineers from Johns Hopkins recently published their proof-of-concept feat in the Journal of Neural Engineering, and believe the experiment may potentially have a significant impact on technologies to restore refined hand function to those who have lost arms to injury or disease.

SEE ALSO: New Era of Prosthetics May Restore Sense of Touch

According to the Amputee Coalition, over 100,000 people living in the U.S. have amputated hands or arms, and most could potentially benefit from such technology.

For the experiment, the research team recruited a young man with epilepsy already scheduled to undergo brain mapping at The Johns Hopkins Hospital’s Epilepsy Monitoring Unit to pinpoint the origin of his seizures.

The young man on whom the experiment was performed was not missing an arm or hand, but he was outfitted with a device that essentially took advantage of a brain-mapping procedure to bypass control of his own arm and hand.

While brain recordings were made using electrodes surgically implanted for clinical reasons, the signals also control a modular prosthetic limb developed by the Johns Hopkins University Applied Physics Laboratory, as seen in this video:


After the motor and sensory data were collected, the researchers programmed the prosthetic arm to move corresponding fingers based on which part of the brain was active. The researchers turned on the prosthetic arm, which was wired to the patient through the brain electrodes, and asked the subject to “think” about individually moving thumb, index, middle, ring and pinkie fingers. The electrical activity generated in the brain moved the fingers.

“The electrodes used to measure brain activity in this study gave us better resolution of a large region of cortex than anything we’ve used before and allowed for more precise spatial mapping in the brain,” said Guy Hotson, graduate student and lead author of the study. “This precision is what allowed us to separate the control of individual fingers.”

The researchers note there was no pre-training required for the subject to gain this level of control, and the entire experiment took less than two hours.

While the experiment follows on the back of previous successful prosthetic advances made by the Johns Hopkins Applied Physics Laboratory, Crone cautions that application of this technology to those actually missing limbs is still some years off and will be costly, requiring extensive mapping and computer programming.

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