The pain loop in the brain is quite large, and involves serotonin receptors.

I have seen 2 presentations of it, at seminars, and even then I can't recall many of the details. (none of the doctors there were doing much better either).

It actually involves many tracts and loops down to the spinal cord in the occipital area of the brain, and back up.

This is very complex, and here are some links:
http://www.wellcome.ac.uk/en/pain/mi...science2.html#

http://www.medscape.com/viewarticle/568704_9
(if you don't have a membership to Medscape you can join for free to view this).

It is from studying this pain loop and the receptors present, that leads to using certain SSRI antidepressants to treat chronic pain.

The ideas proposed at the seminars I attend (and the next one will be May 2011) is to intercept the signals so they do not become "learned" and "fixed". Much of it involves attention and focusing on pain, as enhancers of the signals as well. The brain is rather plastic and learns acts over time. We learn language, music, skills this way. Well, the current thought is that pain also can be learned too.

I do my autohypnosis at night in bed, and also during naps-- if I take a nap that is. I feel most of my pain in my feet at night anyway. Dissociating pain, is very difficult when you do a complex motor task like driving. I have not mastered that one.
And it can be dangerous.

The scales are very vague and open to individual variances... since a doctor cannot feel what you feel, some way to describe it has to be used. Maybe some day a tool will be invented by some brilliant biomedical engineer, that will measure pain and that will be a significant improvement in treatment.