Feb 10, 2007

out of a limb

If you're quoting Oliver Sacks, you're on my automatic to-read list. Gaby Wood gives a brief history of phantom limbs.
But Ramachandran also wanted to help his patients who had pain in their phantoms, or found them paralyzed, as Mitchell's patients had, in the position in which they'd last felt them. He developed a novel technique for this, which involved giving the patient the impression that the phantom they felt but could not see was physically present. He constructed a "virtual reality box," with a vertical mirror inside it and two holes in the front. He asked patients to put both arms through the holes and to move them about in tandem. With the mirror apparently reversing their arms, the patients saw their phantoms actually move. In some cases the paralysis ended; in others the phantoms disappeared altogether, along with the pain. What appeared to have been performed, as Ramachandran put it, was "the first example in medical history of a successful 'amputation' of a phantom limb." "Philip," he said of one of his patients, "seemed to think I was some kind of magician" and indeed the "virtual reality box" he invented is not unlike the cabinet tricks used by stage magicians in the nineteenth century. The doctor had cured a delusion using illusionism.
Thank Helmut for the link.

(I thought I was original with the title, but it's already been used by a cycling organization for amputees and hand cyclists.)

Added: While we're on the subject, how about an artificial ankle joint that lets its wearer walk almost normally within minutes of first putting it on?
Ten healthy volunteers – five female and five male – walked with the ankle muscle deactivated for 10 minutes, before walking with it switched on for another 30 minutes. Video footage, information from the artificial muscle and the electrodes were used to monitor their performance.

Initially, after activating the muscle, walking was difficult because of the extra power provided, as this video shows (7.1 MB, .mpg format). "But people actually learn very quickly," says Ferris.

Subjects had mastered their new powers by the end of the 30 minute session. "It seems that as long as you put the nervous system in control, it's not too difficult to adapt," he adds. A second video shows the same subject using the ankle later on (6.6 MB).

Participants were also able to instantly readapt to using the ankle after a three day break, suggesting that a person's nervous system remembers how to deal with the extra power.
Too cool.

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