Tuesday, June 18, 2013

Melzack and Katz, Pain. Part 9: Phantom pain - in the brain!

The paper, Pain

Part 1 First two sentences Part 2 Pain is personal Also Pain is Personal addendum., Neurotags! Pain is Personal, Always.

Part 3a Pain is more than sensation: Backdrop Part 3b Pain is not receptor stimulation Part 3c: Pain depends on everything ever experienced by an individual

Part 4: Pain is a multidimensional experience across time

Part 5: Pain and purpose

Part 6a: Descartes and his era; Part 6b: History of pain - what’s in “Ref 4”?; Part 6c: History of pain, Ref 4, cont.. : There is no pain matrix, only a neuromatrix; Part 6d: History of Pain: Final takedown Part 6e: Pattern theories in the history of pain Part 6f: Evaluation of pain theories Part 6g: History of Pain, the cautionary tale. Part 6h: Gate Control Theory.

Part 7: Gate control theory has stood the test of time: Patrick David Wall;  Part 7bGate control: "The theory was a leap of faith but it was right!"

Part 8: Beyond the gate: Self as mayor Part 8b: 3-ring circus of self Part 8c: Getting objective about subjectivity


Melzack and Katz discuss the importance of the scholarly research Melzack and Loeser did in 1978, pointing out that paraplegics had pain, even if entire sections of their spinal cord was removed, discussed in this blog series, here

"This concept represented a revolutionary advance: it did not merely extend the gate; it said that pain could be generated by brain mechanisms in paraplegic patients in the absence of a spinal gate because the brain is completely disconnected from the cord. Psychophysical specificity, in such a concept, makes no sense; instead we must explore how patterns of nerve impulses generated in the brain can give rise to somesthetic experience."

This was Melzack, crossing the Rubicon. There was nowhere to go but ahead. A head. Into the brain.

I doubt Melzack much cared after that, about what people might think.. he'd already published the Gate Control Theory with Wall, 13 years earlier, and had been surprised at the upset that had ensued as a result. Maybe he realized he was probably going to have to be the lead dog, pulling most of the sled, but because somebody had to do the heavy pulling, he took it on. 

Positive phantoms

Since then, of course, there have been mad amounts of research into phantom limbs, in both amputees and those who are still intact. Mirror therapy has become tool of choice for helping peoples' brains recover from years-long episodes of I-can't-get-over-myself-itis phantom limb pain. 

Recently (very recently, just this past week!) I learned about the work of Peter Brugger , a researcher in Zurich, in this BodyinMind blogpost [..and knew I had to work it in here some way..]. 

Apparently, as long as 4 years ago, Lorimer Moseley hooked up with Brugger, and they've been merrily working together on all sorts of things, like how phantom limbs move in impossible ways. The implications are pretty staggering, if you're a label-line type researcher. It pretty much suggests that the brain just makes stuff up then goes with it. From Wikipedia
"In 2009 Lorimer Moseley and Peter Brugger carried out an experiment in which they encouraged seven arm-amputees to use visual imagery to contort their phantom limbs into impossible configurations. Four of the seven subjects succeeded in performing impossible movements of the phantom limb. This experiment suggests that the subjects had modified the neural representation of their phantom limbs and generated the motor commands needed to execute impossible movements in the absence of feedback from the body.[14] The authors stated that: "In fact, this finding extends our understanding of the brain's plasticity because it is evidence that profound changes in the mental representation of the body can be induced purely by internal brain mechanisms--the brain truly does change itself." 
G. Lorimer Moseley and Peter Brugger; Interdependence of movement and anatomy persists when amputees learn a physiologically impossible movement of their phantom limb. PNAS October 26, 2009

Negative phantoms

Here is an amazing paper Brugger wrote this year on "xenomelia", a condition in which people disown (their own, healthy!!) limbs as not belonging to their entrenched sense of self, open access.  

Peter Brugger, Bigna Lenggenhager,and Melita J. GiummarraXenomelia: A Social Neuroscience View of Altered Bodily Self-Consciousness. Frontiers in Neuroscience 2013; 4: 204.

People with limb disownership, or xenomelia, want amputations. I don't know about you, but I'm convinced by all this, that the brain has a mind of its own.. not just the body.. Somehow it all braids up in there, in the head, and works together, mostly OK, most of the time, but wow, the aberrations are pretty spectacular. And pain might have something to do with that interrelationship derailing, doncha think? 


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