Researchers at the Georgia Institute of Technology (Georgia Tech) measured arm movements and analyzed brain patterns to determine how new upper-limb prosthesis users best learn to use their prostheses and found that they learned better from someone who also used an upper-limb prosthesis. The authors said that it is the first study to use a unique combination of neurophysiological and task performance methods to investigate prosthetic device training strategies from a cognitive motor control perspective. The results could help reduce the rate at which people with upper-limb amputations reject prosthetic devices.
Participants were people without amputations who donned specially adapted split-hook prosthetic devices to simulate the wrist and forearm movement that people with transradial limb loss experience. Each participant wore movement sensors on his or her elbow and an EEG cap. On the first day of the five-day training and research process, participants performed tasks with the device, such as rotating a block, flipping a spatula, and writing. For the next three days, they watched 30-second videos of someone demonstrating the same tasks. The person shown in the video either wore the same device (a matched limb) or didn’t wear anything on his or her arm (a mismatched limb). On the fifth day, participants tried each task again.
“Those who watched a matched-limb participant did significantly better after three days of training,” said Lewis Wheaton, PhD, an associate professor in the School of Applied Physiology who led the study and directs Georgia Tech’s Cognitive Motor Control Lab. “Their arm movements were more consistent and fluid when they repeated the task. Those who only watched someone without a prosthesis didn’t improve at all.”
The matched-limb participants showed greater engagement of motor-related areas while mismatched-limb participants showed greater engagement of the parieto-occipital system. Matched-limb participants also showed lower movement variability. The results indicate that the type of limb imitated influences neural and behavioral strategies for novel prosthetic device usage, and that common prosthetic rehabilitation with therapists who don’t have amputations may exacerbate challenges in adapting to new motor patterns demanded by prosthesis use. “When amputees watch someone without a prosthesis, it seems that their brain is more concerned with what it’s seeing, rather than concentrating on how to actually do the task,” said Wheaton.
Wheaton is now repeating the study with people who have amputations. Additional steps will attempt to determine whether the results are consistent with different types of prostheses for other parts of the body.
The study was published online October 5 in Neurorehabilitation and Neural Repair.
Editor’s note: This story was adapted from materials provided by Georgia Tech.