Wanting to be an Amputee (and More)
Well I just got back from a nice camping trip (that was far more comfortable than the last.) And tomorrow I am off for a week's vacation (which will be even more comfortable.) So I don't have much time for blogging, but I do have time to link to three interesting recent articles which show what can go wrong when the brain's map of the body is disturbed.
Sensory Motor Mismatch
In this paper, researchers found that inducing an incongruence between visual sensory feedback and motor output exacerbates pain in chronic whiplash patients. This was similar to some of the other experimental illusions I have discussed previously.
In this paper, Lorimer Moseley's group showed that the brain's processing of sensory information is slower in a painful part of the body than a non-painful one. And, that sensation from non-painful body parts are also processed slowly when they are moved very close in physical space to the painful parts. For example, it appears that a pain free hand placed near a painful back will be slightly "neglected" by the brain compared to the other one.
Wanting to be an amputee
In this article, the author describes an extreme case of problems with the body maps. Some people have a condition called Body Integrity Identity Disorder (BIID), whose main symptom is a powerful visceral feeling that one of their limbs does not belong to them, that it is somehow alien. Victims of this horrible disease are completely sane and rational, but experience an overwhelming sense that something is horribly wrong with respect to one of their limbs. The article notes that:
BIID sufferers are willing to do anything to relieve themselves of the condition: whether it’s freezing their legs completely off or to force surgery, blow legs off with a shotgun, or spending time and money travelling to, for example, Mexico to have it done illegally.
Wow. Good incentive to keep those maps accurate.
These three papers represent extreme cases of course, but I think they all have relevance for common experience. I have clients who come to me every day describing a vague sense of discomfort in a certain area. They often have trouble describing the exact nature of the problem. They might say that some area is tight or stiff, not exactly painful, but maybe twisted or "out" of place, or just not right in some undefined way. With these clients, I consider the possibility that they have some minor form of body image distortion. They might think that something is "out" and needs to be popped back "in", but I think the real therapy often occurs by clarifying the body maps.