It can be hard for people who have had an upper limb amputated to learn to use a new prosthesis, but learning from a fellow amputee can make it a little easier.
Most people usually learn by watching a non-amputee demonstrate the device during physical therapy and rehabilitation sessions. But a new study that measured arm movements and analyzed brain patterns shows that people do better when they learn from someone who looks like them.
“We wanted to see if there was something we could improve in therapy that helps amputees—something to refresh the rehab,” says Lewis Wheaton, associate professor and director of the Cognitive Motor Control Lab at Georgia Institute of Technology. “If people with a prosthesis can’t figure it out in the first three days, they tend to give up.”
Prior research found that as many as 75 percent of amputees consider their prosthesis to be primarily aesthetic, and 33 percent reject the device because it’s not practical. Poor training and a bad first experience are often listed as reasons they eventually quit wearing the device.
In the study, published in the journal Neurorehabilitation and Neural Repair, participants wore an elbow-to-hand prosthesis (a split hook device) with movement sensors embedded onto the elbow. The device was designed to limit forearm and wrist movement. They also wore an EEG cap on their heads.
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On the first day, participants tried various tasks (rotating a block, flipping a spatula, writing) with the device. For the next three days, they watched 30-second videos of someone demonstrating the same tasks. The person on video either wore the same device or didn’t wear anything on their arm. On the fifth day, participants tried each task again.
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“Those who watched a matched-limb participant did significantly better after three days of training,” Wheaton says. “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.”
Just as important were the different brain patterns between the two groups. As people watched someone wearing a prosthesis, areas of the brain involved with motor planning were most active. For those watching an able-bodied person, the brain’s visual areas were most dominant.
“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,” Wheaton says.
The current study only included non-amputees watching videos, although Wheaton is now repeating it with amputees. Additional next steps will attempt to determine whether the same results are consistent with different types of prostheses for other parts of the body.
Source: Georgia Tech
