Monday, 12 March 2012

The woman who grew phantom fingers that she'd never physically had

Inside the human brain there is a map of the body drawn in neural tissue. When a person loses a limb, the neural representation of that body part still exists in the map, and more often than not, it continues to give rise to "phantom" sensations. Sometimes neurons in adjacent areas of the body map invade the tissue that represents the missing limb. This can lead to the curious situation where stimulation of a person's face (or other areas) provokes feelings in their phantom limb, as documented by the great neuroscientist V.S. Ramachandran. Cases like this are often cited as evidence for the brain's plasticity.

Now Ramachandran and his colleague Paul McGeoch have reported a phantom limb case that illustrates how aspects of the body map are apparently hard-wired. The case is a 57-year-old woman (known as R.N.) who was born with a deformed right hand consisting of only three fingers and a rudimentary thumb. After a car crash at age 18, R.N.'s deformed hand was amputated, which gave rise to feelings of a phantom hand. Curiously, R.N. experienced her phantom hand as having a full complement of five fingers, albeit that some of the digits were foreshortened. In other words, she was experiencing the sensation of having fingers that she'd never physically possessed.

R.N. was referred to the researchers more than 35 years after her accident, after her phantom hand had become unbearably painful and uncomfortable, including two of the fingers feeling as if they'd become twisted and bent until their tips touched. McGeoch and Ramachandran trained R.N. in using "mirror visual feedback", in which the reflection of her healthy left-hand was seen as superimposed onto where she felt her phantom right hand to be. After two weeks of 30-minutes daily feedback, R.N. was able to move her phantom fingers and was relieved of pain. Crucially, she also experienced that all five of her phantom fingers were now normal length.

McGeoch and Ramachandran said this case provides evidence that the brain has an innate template of a fully-formed hand. Freed from the visual, proprioceptive and tactile sensations of her deformed hand, and aided by the mirror training, R.N.s brain re-instated its innate map of a normal hand. "There appears to be a 'hard-wired' innately specified scaffold for body image," the researchers said. This account also helps explain the occurrence of phantom limbs in people born with missing limbs.

The researchers conceded that they were taking R.N.s account of her feelings on trust. It's possible she was confabulating - although they think this unlikely. If she were, McGeoch and Ramachandran think it more likely that R.N. would have claimed to have had normal length fingers prior to the mirror training.

_________________________________ ResearchBlogging.org


McGeoch, P., and Ramachandran, V. (2012). The appearance of new phantom fingers post-amputation in a phocomelus. Neurocase, 18 (2), 95-97 DOI: 10.1080/13554794.2011.556128



Post written by Christian Jarrett for the BPS Research Digest.

3 comments:

  1. Anonymous11:33 pm

    The article published by McGeoch and Ramachandran does not provide any information about when they worked with the woman with the painful phantom limb. The most recent reference cited by the article in from research in 2000.

    A lot has happened in the past ten years and most of the research does not support the theories developed by Ramachandran in the 1990s. If you were to read the recent articles published by Lorimer Moseley and Herta Floe (two of the world's leading pain researchers) you would discover that mirror therapy is not regarded as an effective treatment for phantom limb pain. It is sometimes incorporated into a strategy known as graded motor imagery. The information you cite is very much out of date. It's circa 1994,

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    1. hi. i am RN. this was published online in 2011, i believe. it is not circa 1994. the mirror therapy did not cure my pain, this is true. but it did relieve the sensation of constantly clenching my hand. and it allowed me to move my digits, as i had only tried to do one time in all the years since my amputation. at that time it was so horrible that i never tried again until meeting dr rama, and dr paul. unfortunately, from the many things i have read about this on the net, it has been made to sound as if all of a sudden i began to feel 5 digits. when actually the change was very slow over the course of many, many years. i had no idea that anyone other than researchers, or possibly drs would ever read about my case. i did not make anything up, or try to recieve attention, as i have read elsewhere. dr rama and dr paul have helped me immensly. i had no idea why i could feel 5 digits. i had asked 2 drs previously, only to be looked at as if i was a nut case. i KNOW that dr rama and dr paul are correct about the hardwired map in the brain. and finally, i do not care what anyone else thinks about it. nemia rucker https://www.facebook.com/NemiaRucker

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  2. Anonymous10:41 pm

    Actually this RCT from 2007 shows that mirror therapy for phantom limb pain is an effective treatment. http://www.nejm.org/doi/full/10.1056/nejmc071927

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