Slashdot Mirror
VR Cures Amputees' Phantom Limb Pain
An anonymous reader writes, "Scientists have developed a virtual world like Second Life where real-life amputees have their limbs restored. The experience can cure patients of the perception of pain in their missing limbs. From the article: 'The machine is designed to combat phantom limb pain (PLP) — a sensation of pain experienced by an amputee that appears to originate in the missing limb. Intriguingly, researchers have discovered that if a person's brain can be tricked into believing they can see and move a "phantom limb," this motion reduces the perception of pain in PLP.' The graphics used by the computer look very crude, almost comically so, but apparently the system works."
The guy got his dick back.
I read in a popular science type book by VS Ramachandran that some people can be tricked into recovering from phantom pain simply by looking at a mirror that gives them the appearence that their limb is still there. Near verbatim what he says is, "well, we could've built a big expensive virtual reality device to try this... but we decided to go with something cheaper: mirrors". This was, supposedly, how scientists figured out that the phantom limbs could be addressed by visually "fooling" the brain.
The wikipedia article on this mirror device is here.
The doctor is V.S. Ramachandran, and his work is fascinating. His book on phantom limb syndrome and other psychological conditions is called _Phantoms_in_the_Brain_, and it's thoroughly enjoyable; an easy read (especially if you have no previous exposure to the field), but not so dumbed down as to insult your intelligence. He frequently uses very simple approaches to diagnosing and studying these cases.
His newer book is called _A_Brief_Tour_of_Human_Consciousness_, which deals with some of the same issues, but also introduces his more recent studies.
/Not a shill
//Just a fan of brain disorders
///that doesn't sound right
Slashdot: News for nerds. Stuff tha-- MICRO$OFT IS THE DEVIL!!1
That is supposed to be a poison-rejecting mechanism, actually - evidently, some poisons make you feel as if you were moving, although you're not; this is the mechanism which recognizes (or "recognizes") such behaviour and reacts accordingly - by forcing the poison out the same way it supposedly came in by.
Ignore this signature. By order.
Doctors used to think that if you cut the nerve to something, you wouldn't feel anything from that area because your brain wouldn't get a signal from that area.
As it turns out, it's nowhere near that simple. You can't just transect a nerve to make someone with a really damaged body stop feeling pain in that area, and for the same reason, amputees still get sensations from limbs that aren't there and nerves that aren't connected to anything.
The brain doesn't recognize pain based on polling a nerve for pain signals and determining whether there's pain if the nerve is being triggered or if it is not being triggered. Rather, it's a contextual thing. The brain recognizes a certain kind of amalgamation of signals as pain, and the lack of pain as a different collection of signals.
So if you just cut the nerve, it doesn't feel a lack of pain - without any signal telling it that there's no pain, it just tends to try and match what input it can to the signals it previously had from that limb. This results in all sorts of strange sensations in a limb you don't even have! A lot of times, the brain will try and model sensory information on the closest thing to the absent limb - if you're missing your right leg, it checks input from the left as a guide to what it should be feeling.
Doctors used to think people were crazy for feeling pain in limbs that they didn't have. Now they know better. And much of this knowledge was gained from experiments that involved amputating limbs and digits from monkeys, so don't let anyone tell you there's no point to animal testing (they used anesthesia, so it wasn't too bad for the monkey).