Saturday, June 29, 2013

Melzack&Katz, Pain. Part 11b: intro to a new conceptual nervous system

The paper, Pain

Most recent blogpost: Part 11We need a new conceptual brain model!


Beyond the Gatecontinued

The next section is "The Body-Self Neuromatrix." Here is M&K:
"The body is felt as a unity, with different qualities at different times." 
Sometimes it feels charged, ready to rock and roll, and other times it feels like a lazy hound dog. 

"The brain mechanism that underlies the experience also comprises a unified system that acts as a whole and produces a neurosignature pattern of a whole body.18,19,21"
Same three references as yesterday.

"The conceptualization of this unified brain mechanism lies at the heart of the theory, and the word ‘neuromatrix’ best characterizes it." 
"The neuromatrix (not the stimulus, peripheral nerves or ‘brain center’) is the origin of the neurosignature; the neurosignature originates and takes form in the neuromatrix." 
I guess this means the brainstem isn't it? Sorry Damasio. I thought "brainstem" might be it (see yesterday's post, which I edited to include a picture from the TEDtalk), but Melzack is saying, there isn't any "center" to any of this - it's the whole thing operating. It's the verb of it, not the noun. 

Maybe it's the so-called "Default Mode" then... 

"Though the neurosignature may be activated or modulated by input, the input is only a ‘trigger’ and does not produce the neurosignature itself."
Input represents a perturbation of it.

Mmmm... chocolate donuts..
"Packaging Machine wraps delicate food products"
"The neuromatrix ‘casts’ its distinctive signature on all inputs (nerve impulse patterns) which flow through it."
I can't help but think of a factory situation. 

"Finally, the array of neurons in a neuromatrix is genetically programmed to perform the specific function of producing the signature pattern."
Certain cells operate with very little stimulus - I do recall Buzsaki talking about spindle cells. 

[Here is a link to a page in a book, discussing the matter. A link to the book itself.Here is a transcript I wrote up for Ginger Campbell's interview with him. Here is a series I wrote in 2008 about Buzsaki's book.] 

"The neuromatrix, distributed throughout many areas of the brain, comprises a widespread network of neurons which generates patterns, processes information that flows through it, and ultimately produces the pattern that is felt as a whole body."
So.. it's not strictly thalamus, brainstem, hippocampus.. although I bet those are where the pacemaker systems will be found. And we shouldn't forget about locus ceruleus. Here are some notes I made about LC, back when I was avidly studying up on it. 

"The stream of neurosignature output with constantly varying patterns riding on the main signature pattern produces the feelings of the whole body with constantly changing qualities."
Yeah... I'm a bit lost right now. It looks like we have come to some rapids that we'll have to portage around. I'm going to go to the Hebb lecture, see if I can find a way to proceed. Everybody out of the river - we have to make a portage around some falls now. Yeah.. I know. Sucks, but we can't really paddle up the rapids as if we were agile salmon. 

In the section just after his 4 conclusions, Melzack opens with a short paragraph, titled "Sketch for a New Conceptual Nervous System":
"Phantom limb phenomena confront us with the most challenging problems in psychology: awareness; the self; the qualities of experience; the nature of knowledge and reality. These ancient problems have been debated throughout the centuries and continue to elude us. In recent years we have tended to ignore them, explain them away, even deny their existence. We can no longer evade them if we want to find an answer to phantom limbs."
He continues: 

The Conceptual Nervous System
"Before I embark on a search for a new understanding of brain function, it is essential to recognize the importance of Don Hebb's (1955) insight that psychologists who seek global answers to major problems can deal only with a conceptual nervous system."
The reference goes to Hebb, DO; Drives and the CNS (Conceptual nervous system) Psychological Review 62, 243-254.  (Full text here!) Aha. This looks like a nice place to stop and have lunch: 
"The problem of motivation of course lies close to the heart of the general problem of understanding behavior, yet it sometimes seems the least realistically treated topic in the literature. In great part, the difficulty concerns that c.n.s., or "conceptual nervous system," which Skinner disavowed and from whose influence he and others have tried to escape. But the conceptual nervous system of 1930 was evidently like the gin that was being drunk about the same time; it was homemade and none too good, as Skinner pointed out, but it was also habit-forming; and the effort to escape has not really been successful. Prohibition is long past. If we must drink we can now get better liquor; likewise, the conceptual nervous system of 1930 is out of date and -- if we must neurologize -- let us use the best brand of neurology we can find.
Though I personally favor both alcohol and neurologizing, in moderation, the point here does not assume that either is a good thing. The point is that psychology is intoxicating itself with a worse brand than it need use. Many psychologists do not think in terms of neural anatomy; but merely adhering to certain classical frameworks shows the limiting effect of earlier neurologizing." - Hebb 1955
Later we'll go back to Melzack 1989 (our portaging) and find out more about what Melzack thought about this, and why he brought it up. [It was probably more than just a polite nod to the occasion itself, the official D.O. Hebb Lecture... he says it was an important insight.]


Previous blogposts

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
Part 9: Phantom pain - in the brain! Part 9b: Dawn of the Neuromatrix model Part 9cNeuromatrix: 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." Part 10b: Conclusion1: The brain generates its own experience of being in a body Part 10c:Conclusion 2: Your brain, not your body, tells you what you're feeling Part 10dConclusion 3: The brain's sense of "Self" can INclude missing parts, or EXclude actual parts, of the biological body Part 10eThe neural network that both comprises and moves "Self" is (only)modified by sensory experience

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