The first successful attempt to move individual fingers using a mind-controlled prosthetic arm has been achieved by physicians and biomedical engineers at the Johns Hopkins University School of Medicine. The news comes shortly after the announcement of a tiny, bionic spine that aims to allow people to control prosthetic limbs with their subconscious thoughts, as HNGN previously reported.
While the man who participated in the experiment was not missing an arm or hand, the device utilized a brain-mapping procedure in order to bypass the control of his own arm or hand. Scientists believe that the technology may help those who have lost arms to injury or disease regain hand function.
"We believe this is the first time a person using a mind-controlled prosthesis has immediately performed individual digit movements without extensive training," Nathan Crone, senior author of the study, said 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."
Before connecting the prosthetic arm, the team mapped and tracked specific parts of the subject's brain using an array of 128 electrode sensors and determined the parts responsible for moving each finger. Afterwards, they programmed the prosthetic arm to move the corresponding fingers. The team also measured the patient's brain activity involved in tactile sensation using a glove with small vibrating buzzers that went off individually on each fingertip and determined the unique brain activity for each finger connection.
After gathering the aforementioned motor and sensory data, the team programmed the prosthetic arm to move specific fingers depending on which part of the brain was activated. The arm, which was connected to the patient's brain via electrodes, read the electric activity in the patient's brain and moved his fingers via this analysis.
"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, lead author of the study. "This precision is what allowed us to separate the control of individual fingers."
The accuracy of the limb was initially 76 percent, but when the researchers attached the ring and pinky fingers together, this number shot up to 88 percent.
"The part of the brain that controls the pinkie and ring fingers overlaps, and most people move the two fingers together," Crone said. "It makes sense that coupling these two fingers improved the accuracy."
Despite the promise of this technology, it is still years off from being functional for those with actual missing limbs and will require ample time and money, as well as extensive brain mapping and programming.
The findings were published in the Feb. 10 issue of the Journal of Neural Engineering.
