Reports show that the first successful effort to wiggle fingers individually of each other using mind-controlled artificial arm. These reports come from physicians and biomedical engineers from John Hopkins.
A Huge Leap Forward
The report has shown a huge advance in technologies to restore hand function to those who have lost arms to injury or disease. The young man on whom the experiment took place, was missing neither a hand or an arm, but in fact his brain was used to bypass control of his own arm and hand, and when fitted with the device, could show its use.
Senior author Nathan Crone, MD professor of neurology at the John Hopkins University School of Medicine reports “We believe this is the first time a person using a mind-controlled prosthesis has immediately performed individual digit movements without extensive training. This technology goes beyond available prosthesis, 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”.
Testing the Arm
The experiment took place on a young man who had epilepsy and was already scheduled to undergo brain mapping at The John Hopkins Hospital to pinpoint the origin of his seizures. Whilst the brain recordings were taking place using surgically implanted electrodes, the signals were also used to control a prosthetic limb developed by the Applied Physics Laboratory.
Of course, extensive research ensured his safety and completion of the task by mapping the subjects brain and finding the different parts responsible for moving each finger and then the prosthesis was programmed to the corresponding fingers.
By using 128 electrode sensors, the computer program they had created made the man move each individual finger on demand and recorded the areas of the brain that “lit up” from the electric signal that showed movement.
As well as recording and collecting data on motor movement, the researchers measured the man’s electrical brain activity involved in tactile sensation – this was done by fitting a specialised glove with small vibrating buzzers on each fingertip.
After all of the data was collected, the researchers programmed the prosthetic to move each finger based on the patient’s thoughts. Once turned on, they would be asked to think about moving each finger individually causing the electrical activity generated in the brain to move the fingers.
Graduate student and lead author of the study Guy Hoston reported “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. The precision is what allowed us to separate the control of individual fingers”.
The original accuracy of the limb was around 76 percent, however when on the of researchers coupled the ring and pinkie finger together, the accuracy skyrocketed to 88 percent.
“The part of the brain that controls the pinkie and ring fingers overlaps, and most people move the two fingers together. It makes sense that coupling these two fingers improved the accuracy” Crone said.
The researchers reported that there was no pre-training necessary for the subject to gain the same level of control as the experiment, and that the entire process to less than two hours to fully complete.