>I have read that some types of chronic pain can persist long
>after there is no clear indication for it. It seems the body can
>"learn" pain if given enough time to associate with it. Could the
>below snip also explain this?
>>>Ed Ergenzinger wrote in message <35741D3E.90C81D67 at bgsm.edu>...
>> In the somatosensory system perceptual anomalies such as
>>phantom limb have been linked to reorganizational changes
>>injury. The association between phantom sensation and
>>central maps would seem to indicate that while neurons can
>acquire new receptive fields and become activated by input from
>new portions of the body surface, the result of this activity is
>interpreted as coming from old portions of the body surface.
Pain is a discrepant signal on two or more channels that are
incongruent. Therefore pain can be learned, but it can also
be removed by learning.
Consider the case of a person with phantom limb pain
who puts his good left arm on a table and his stub of
his right arm on a table behind a mirror. By carefully
positioning the mirror so that it looks like the left arm is
the right arm in the mirror some interesting events can
be set up.
Now both hands are moved together for 15 minutes
but your visual attention is on the mirror right hand.
((This effect can be created in normal people for hand displacement.))
When the mirror is taken away the pain is significantly reduced.
The last message into the brain is that the right arm is OK and the
movements occured over a wide range of behaviors.
The no pain state is now registered.