Twiddling Thumbs And Planning Prosthetics
Have you ever wondered how your favorite superheroes or supervillains controlled any new limbs? Like Dr. Otto Octavius in “Spiderman” with his extra tentacles, or Iron Man controlling every bodily movement of his suit. What would life be like with an extra arm and could you control it just like you currently control yours? While not so important for superheroes, in the medical sciences sector, only 45% of all arm amputees choose to wear their prosthetics regularly (Paper by Jang et. Al) and this begs the question, how do we build something that acts like the Iron Man suit.
Researchers at the University College London (UCL) were recently investigating a similar problem: Do people with prosthetic arms internalize their prostheses as a tool or as their hand? The short answer is NO to both the prostheses and the tool. If you have spent time building out IKEA furniture as I have, you would have noticed that it is only a matter of time when your hand starts acting like an extension of the Allen wrench they provide with each piece of furniture. The ideal candidates for this research would be surgeons who spend the better part of their day holding tools and using them as extensions of their limbs, but as surgeons are pretty busy, the researchers used London’s street cleaners who use litter picking metal poles.
The Third Thumb experiment includes a 3-D printed thumb that is secured to the right hand of a person and is controlled by two pressure sensors under their toes. This was attached to 36 people who were right-handed and were asked to wear this device around for 5 days for at least 2 hours a day. In an interview with Scientific American, the researchers discussed that their primary objective was to see how the visual cortex of the brain reacted to seeing these prosthetics or devices. This region of the brain was selected because there is a visual area of the brain that represents the hands and an overlapping area that represents tools. The expectation was that they would see activity in one of these areas to determine what the brain registers such prosthetics as.
Participants in the research were asked to perform multiple tasks like pick up balls, peel bananas, make coffee, etc. using just their right hand, and were even blindfolded or distracted. Although awkward at the beginning, they managed to perform these tasks and even took the thumbs home with them so that they could wear them between two to six hours. fMRI scans of the visual cortex were taken before and after the 5-day experiment to see how the device was processed in the brain. Unfortunately, the brain could not be studied while using the device as it was not safe to use in an fMRI scanner while wirelessly transmitting signals from the feet.
At the end of the study, even though the brain did not classify the device as a hand or a tool, people connected with the thumb emotionally, and felt like a part of them was left behind at that experiment. While this experiment did not give us a conclusive answer on how prosthetics are viewed in our mind, it opens up the discussion on how much more research is required to design and create better prosthetics to support those who suffered a loss of limb. Hopefully, the next design allows us to walk and drive while using our thumbs and carries all our heavy grocery bags without us having to think much about it. If you have a passion for design and technology, this is the next big tech space you should be looking into!
