People who have had paralysis or an amputation have lost most or all of their sense of touch. People have been trying to make prosthetics that can combat this issue and a group of researchers have

Recent breakthroughs have allowed people who have lost the use of a limb to move a prosthesis and handle objects. But movement alone isn’t enough. The ability to perceive what you touch is fundamental to precisely controlling and accepting a prosthesis as a part of the body.

Dustin Tyler from Louis Stokes Veterans Affairs Medical Center in Cleveland, Ohio, and his colleagues were able to discover this a few weeks ago.The found how to transmit long-term, realistic sensations such as being able to recognize the feel of cotton.

It works so well that one man, on leaving the lab where he tried the prosthetic, said it was like leaving his hand at the door.

Recently people have tried to recreate a sense of touch by delivering vibrations to a person’s residual limb that equal the amount of pressure on the prosthesis. This has proved to be more distracting because people have tried sending electrodes to the nerves but they slowly diminish over time.

That’s why Tyler’s team tried something else more complex. They implanted a bunch of electrodes around the three main nerves that would usually transmit sensory information of two people’s limbs. Each bunch of electrodes were linked to wires and could stimulate different parts of the nerves. The wires were attached to a machine that provided a stream of electrical pulses. This was connected to the prostheses the men were already using.

“As soon as we stimulated the nerves in the first subject, he immediately said ‘that’s the first time I’ve felt my hand since it was removed’,” says Tyler.When the electrode were turned on the men felt a tingling sensation that went through the whole hand.

With a real hand, touching distinct objects results in different patterns of nerve activity. To mimic this, the team altered the frequencies and intensities of electric pulses. After a healthy dose of trial and error, the first subject said “that’s not tingling any more, it feels real”.

Before researching this topic, I never really thought about how people with prosthetics aren’t able to feel anything with that part of their body. This improvement will help make injured people to be the most normal people they can be. However, how do they know if this will leave nerve damage or not? Since they’re connecting the electrodes to the nerves? It will be interesting to see how this advances in the future.

http://www.newscientist.com/article/mg22429914.400-prosthetic-hand-recreates-feeling-of-cotton-bud-touch.html#.VEm5XYd4Xdk

http://news.nationalgeographic.com/news/2014/02/140222-artificial-limbs-feeling-prosthetics-medicine-science/