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 7b: Gate 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
Part 9: Phantom pain - in the brain! Part 9b: Dawn of the Neuromatrix model Part 9c: Neuromatrix: MORE than just spinal projection areas in thalamus and cortex Part 9d: More about phantom body pain in paraplegics
Part 10: "We don't need a body to feel a body."
Imagine our little river completely disappearing from the surface of the landscape for awhile. We are in space; we see it flowing along, then bam, it's gone! Where did it go? If we fly in closer for a look, we see it is pouring into a subterranean sinkhole, and have no idea from where it will emerge. It could be anywhere in a 360° circle, of undetermined radius.
That's where my meander is at right now; it is as though it is forced to obey gravity and pour straight down into this big sinkhole, into some deep cave, and flow there for awhile, while we examine Melzack's "4 conclusions" - the mysteries about pain and the brain that forced him to think long and hard about the conventional theory of pain-as-input, and consider pain as an output.
From the Melzack and Katz paper:
"First, because the phantom limb feels so real, it is reasonable to conclude that the body we normally feel is subserved by the same neural processes in the brain as the phantom; these brain processes are normally activated and modulated by inputs from the body but they can act in the absence of any inputs.
Get ready for excerpts from Melzack's 1989 paper,
- vivid sensory qualities
- precise location in space
- (if painful, demand on awareness can become overwhelming)
- phantom becomes even more "real" when an artificial leg or arm is worn
- phantom changes shape/lengthens to fully occupy a prosthesis (Riddoch 1941)
- details of the past can be "felt" (e.g., former bunion, a ring on a former finger)
- if the patient had Parkinson's, tremor may be experienced in the phantom limb
- tardive dyskinesia may be induced in phantom limb by drugs (Jankovic & Glass 1985)
- phantom arm usually hangs by side, moves in coordination with other limbs; in some it is felt to be stuck in an uncontrollable awkward angle (Poeck 1964, 1969)
Phantoms of other body bits
- penis (Heusner 1950)
- breasts (Weinstein, Vetter & Sersen 1970)
- all sensory roots are ripped from spinal cord
- "the phantom "fills" the totally insensate arm and hand, and may feel normal except that movement is not possible" (Wynn-Parry 1980)
- telescoping does not occur in this situation (possibly because visual reinforcement is readily available)
- dissociation may occur when patient's eyes are closed and arm is moved to a new location (Melzack & Bromage 1973); when patient can see the new position the phantom moves instantly into it
- patients usually report they can still feel their lower body and legs (Bors 1951, Conomy 1973) and deny phantom
- dissociation occurs when legs fall out of bed in the dark, or body is moved by someone else, without the person being told about it, or being able to watch
- dissociation also occurs when activity is felt to occur in genitalia or rectum, but none occurs
- in quadriplegia associated with complete spinal break patient may experience orgasm (Money 1960)
- stimulation of nipples or other skin tissue above level of break combined with fantasy or actual activity with a partner may produce experience of orgasm in genital area (Verkuyl 1969) [no link or abstract available]
Melzack's concludes from these data [sentence by sentence]:
"My conclusion from these data is that the phantom represents our normal experience of the body."
"It is not a pathological entity due to a psychological aberration, or due to an abnormal functioning of the brain."
[I.e., there is nothing weird about them (i.e., the people experiencing the phantoms), even though their experience may seem kind of weird - to us. But we can't really know what it's like to be them. Can we? I think not.]
"It is the body we always feel, but without the input that normally modulates the central neural processe that produce the experience."
[Let's chew on that just for a moment.. it's the body we always feel.. indivisible from our experience of it.. but here, the body they feel now is divisible from their experience of it, because they can't move it anymore. They don't get any sensory or proprioceptive input. NONE. Zip. Nada.
So... where is the "feeling" of having a body coming from?
Has to be coming from the brain itself, doing the best it can with what it has, some sort of body blueprint up in there.]
"The tingling, strange positions, pain, and other abnormal aspects are due to the absence of input to a neural network which I describe later."
[Moseley talks about cortical disinhibition, and how that can permit ratcheting up any sort of brain behaviour, like when he found himself playing Orthinology instead of Amazing Grace on the clarinet, as if it were a context-initiated OCD tic. Also, in stroke, one entire hemisphere becomes disinhibited by the other.]
"But that neural system exists within the brain even when the body input is cut off by amputation, nerve avulsion, or spinal break. It is evident that our experience of the body can occur without a body at all. We don't need a body to feel a body."[This big green sentence impressed me a lot. It's what made me want to delve into and slowly meander through this whole paper. It's an awesome sentence. I think it deserves to become a meme.]
The experience of the body is produced by networks in the brain, which are normally triggered or modulated by inputs from the body. An analogy is the power of a car which derives from the engine, not the gas pedal."[Nice analogy Melzack. Exactly.
Maybe also like the power of a computer comes from all the hard drive inside it, and the electrical grid into which it is plugged, not from the keyboard or the person posting kitty videos to Facebook with it.]
The experience of a phantom limb has the quality of reality because it is produced by the same brain processes that underlie the experience of the body when it is intact."
Next we will ponder "Qualities of phantom limb experience" as we continue our meander underground in the cave of this 1989 paper.
Richard A. Sherman, Marshall Devor, Kim Heermann-Do; Phantom Pain. Springer; 1997 edition (Nov 30 1996) (Google eBook)
4. Kyeong-Eon Park, Kwang-Seong Cheon, Seong-Ho Ok, Young Ju Jeong, and Heon Keun Lee; Phantom bladder pain. Korean J Anesthesiol. 2012 October; 63(4): 376–377. (Full text)
Targeted mini-strokes produce changes in interhemispheric sensory signal processing that are indicative of disinhibition within minutes. PNAS | May 31, 2011 | vol. 108 | no. 22 | E183–E191 (Full pdf)
"An emerging consensus from human imaging studies is that the most successful recovery occurs in individuals that exhibit relatively normal lateralized patterns of sensory activation within the lesioned hemisphere, whereas patients with larger stroke, who often show bilateral cortical activation, typically have less complete recovery"