Modern science can provide highly advanced prosthetics for those who lost their limbs. Hitech prostheses perform various functions and may even look realistic. Obviously, it will be decades till we have prostheses that accurately mimic actual human limbs, but some advancements have been made already.
Scientists from the Swiss Federal Institute of Technology in Zurich, for example, found that tying prosthetics sensors into a person’s neural system makes the prostheses feel lighter.
Sensors in the artificial foot gather information and transmit it to the electrodes in the thigh. Image credit: ETH
What are we even talking about? Well, even if prostheses perform their functions, they usually do not provide any feedback. People do not feel their legs, for example, because they are made of carbon fibre. This is not just a question of discomfort – amputees don’t feel when they are stepping on something sharp, hot or unstable, which can be very unsafe. The feedback that you get from your own limbs is a very important interaction between you and the world and scientists are trying to provide it to people wearing prostheses.
Interestingly, amputees often feel that their leg prostheses are too heavy, even when they are made from advanced materials and weigh actually less than their natural limb. Scientists think that this sensation can be alleviated by restoring that feedback – they can connect some sensors in the artificial foot to the patient’s nervous system. There are several sensors in the prosthetic leg. Impulses from them are converted into electrical signals that then travel to implanted electrodes in the thigh and into the nervous system. This improves safety and, as this new study showed, reduces perceived weight of the prostheses.
Participants of this study had to perform some tests with neurofeedback switched on or off. Their healthy foot was weighed down with some weights and participants had to compare their perceived weight. Scientists found that neurofeedback reduced the perceived weight of the prosthesis by 23 %, or almost 500 grams. Stanisa Raspopovic, lead author of the study, said: “Neurofeedback not only enables faster and safer walking and positively influences weight perception. Our results also suggest that, quite fundamentally, it can take the experience of patients with an artificial device closer to that with a natural limb.”
We have so many smart devices nowadays and pay for them thousands and thousands of dollars. However, many people are still walking around with dumb prostheses. Hopefully the next stage of their evolution is introduction of neurofeedback to mass-production.