It sounds like something out of a science fiction movie, but scientists led by Todd Kuiken at the Rehabilitation Institute of Chicago may have broken through a barrier that could lead to the establishment of connections between prosthetic devices and the human nervous system.
A 54-year-old hydro worker who lost both arms after being electrocuted and a 24-year-old woman who lost one arm after a crash underwent the surgery.
After several months for the nerves to re-establish themselves in the chest muscles, the two patients were able to feel physical touch, sensations of heat and cold and electrical charges. One of the patients was even able to feel the prosthetic limb's skin stretching and the joint of her ring finger extending.
As reported by AFP
the scientists were quoted from their online edition of the Proceedings of the National Academy of Sciences
as saying "Our results illustrate a method for creating a portal to the sensory pathways of a lost limb...This work offers the possibility that an amputee may one day be able to feel with an artificial limb as though it was his own."
Co-Author Paul Marasco, who is a sensory neurophysiologist at the institute was quoted by the Toronto Star as saying "The idea that these nerves were able to regenerate through the skin over such large distances did come as quite a surprise to us," adding that "The idea was that this would help these individuals control limbs much more effectively."
A sensor installed in the fingertip of the prosthetic arm allows the patient to measure how much pressure an object is being gripped with. The nerve ending in the chest area that corresponds to the fingertip is then pressed with a plunger device. Existing prosthetics can offer one way communication from the body to the arm, as a way of controlling them, but until now, the artificial limb had no way of sending signals back.
There may be limits to the complexity of sensation that is possible at this time, as neither patient was able to experience a full recovery, but in both amputees, the nerves leading to the missing limb had not been used in over a year. The researchers suggested
that the "sensory pathways remain intact despite prolonged lack of use." Nevertheless, the possibilities for the future of bionics seems to have taken a great step forward.