MoonChild, on Nov 10 2009, 12:09 PM, said:
I beg to differ here CaveRat.
When you said
If you loose an arm, the nerves that allowed us to feel sensation in that arm are not entirely gone. A part of them remains between the stump & the brain & continues to function.
Now, how can this be true? When a finger is cut off, so does the nerve. The nerve runs from the brain till the end of the finger, and it's functionality is not merely to feel the said finger, but the entire route it runs through. For the same reason, when a finger is cut off, so does the functionality of that nerve with relation to that finger. So the phantom limp phenomenon cannot be satisfactorily explained in this manner.
A fair question. Let me see if I can explain it satisfactorily.
This is not a new idea, it is commonly accepted in the medical community. It should be noted though that there are differing opinions on some of the finer points.
The part of the nerve that served the finger is still in the stump, alive & well. The nerve still continues to feel and it has a portion of it that is dedicated to the finger still. For whatever reason, the brain still interprets some of the signals as coming from the finger.
Maybe it will help to think of it as a a telephone cable? We have a cable, with several tephone lines in it. One of the phones I torn out of the wall. The cable is still intact and functioning. Someone that dials the number of the torn out phone might still hear static if the wires where touched together. I do not think this is a perfect analogy, but I think it works.
There is also the idea, pioneered by one of your countrymen, called neuroplasticity. In short, that the brain can sometimes remap the behavior of its neurons. This could help to acount for phantom limb sensatins.
Here are some links:
Hope this helps clear up my opinion.
Canis (not Caverat