Melzack & Katz, Pain. Part 12f: Surfacing out of basal ganglia

The paper, Pain

Most recent blogposts:

Part 12: Action! 12b: Examining the motor system, first pass. 12c: Motor output and nervous systems - where they EACH came from Part 12d... deeper and deeper into basal ganglia Part 12e: Still awfully deep in basal ganglia

SEE ALL PREVIOUS BLOGPOSTS IN THIS SERIES LISTED AT THE END

OK, we're turned around now and heading back to the Melzack & Katz river we had been traveling on, but I thought, since it'll be a few days before we get back to where we first turned off, I'll keep posting info Peggy Mason provides in her wonderful text, Medical Neurobiology, written in easy page-turner style. [I gotta say, I was up in the middle of the night reading about basal ganglia, so it's not an easy topic to let go of, obviously.] 

Here is a great sample of her clarity, a summary after about 20 pages of detailed explanation about how info gets in to basal ganglia, how its handled, how it's allowed through: 

"Every time we act, the cerebellum and basal ganglia, the two great loops in the brain, receive information about the action generated from cortex. Both structures communicate indirectly with the motor hierarchy, only affecting motor neurons and motor interneurons via a circuitous route. Both structures receive at least an order of magnitude more information than they send out to target structures, making them processing bottlenecks that reduce an overwhelming confusion of conflicting input to a concise and decisive winner-takes-all output. Further, the basal ganglia are critical to, and the cerebellum may influence, many nonmotor functions, processing thoughts, emotions, and memories, all of which, of course, ultimately influence movements. Even the functions of the two, in sequencing movements and learning associations, overlap. 

 
" In marked contrast to the case with the cerebellum, the basal ganglia do not receive spinal input. Instead, input to the basal ganglia comes from virtually all areas of the cerebral cortex, as well as from subcortical regions that can themselves direct movement, such as the superior colliculus. Whereas some efference copy input to the cerebellum arises from spinal border cells, efference copy input to the basal ganglia comes from cortical and brainstem motor control centers exclusively. Thus, the cerebellum receives information about muscle contractions, whereas the basal ganglia only receive input about movements and actions. Sensory input to the cerebellum comes from the spinal cord and represents the sensory consequences of movement termed reafference. In contrast, neurons in cortical and brainstem regions interpret and then present sensory information about the world to the basal ganglia. Consider the sequential versions of an action, from motivation and selection of a goal in the prefrontal cortex to action in motor cortex, to movement in the ventral horn interneurons, and muscle control in the α- motoneurons. The basal ganglia receive motor information biased toward goal selection and action whereas the cerebellum receives information biased toward movement and muscle contraction.  

"The cerebellum smooths out movements, important and trivial ones alike, whereas the skeletomotor loop of the basal ganglia ensures that salient actions take priority over automatic, mundane ones. The nonmotor functions of the cerebellum and basal ganglia may similarly diverge with the cerebellum focusing on automatisms and the basal ganglia on matching motivation, thought, emotion, strategy, and movement to urgency and circumstance.  

"Both the cerebellum and basal ganglia support operational learning. The cerebellum associates sensory input with motor output, so that a set of inputs related to the body and the outside world - an entire sensory gestalt - becomes associated with a particular movement. In contrast, the basal ganglia associate self-generated actions with their consequences, biasing present and future selection of actions toward previously rewarding ones. Ultimately our actions are those dictated by the cerebellum and the basal ganglia, incorporating influences from the sensory world as well as from our cognitive, motivational, and emotional states." p. 579-80:

All the bolds are hers. 

Here are the bits that really caught my eye: 

Processing bottlenecks

"...processing bottlenecks that reduce an overwhelming confusion of conflicting input to a concise and decisive winner-takes-all output."

If both basal ganglia and cerebellum receive "at least an order of magnitude" more information than they let through, then that is some heavy darn braking they are required to do! How is all the other info (that doesn't get through) handled? Is it dampened or deconstructed or recycled somehow?

Basal ganglia and nonmotor function

"the basal ganglia are critical to...many nonmotor functions, processing thoughts, emotions, and memories, all of which, of course, ultimately influence movements."

This kind of puts them in the middle of not just the physical brain, but of everything the brain "does." In the middle of the neuromatrix, not just off to the right of the diagram. 

Cerebellum and basal ganglia are a team

"Even the functions of the two, in sequencing movements and learning associations, overlap."

So nice they work together so well. I suppose that will happen over 500 million years - kinks get smoothed out quite a bit.

Projections to basal ganglia

"basal ganglia do not receive spinal input"

They really do only work with brain input, none from the "body." 

Note to self - study up on superior colliculus. It has something to do with reflexive vision and output to neck muscles or something.. handy if something (like a predator sliding through the grass) happens to catch the eye.

Culture, habit formation

"neurons in cortical and brainstem regions interpret and then present sensory information about the world to the basal ganglia."

They only receive info that has already been "milled" by the rest of the brain. The rest of the brain has already been programmed by "culture." 

"The basal ganglia receive motor information biased toward goal selection and action"

Unless the patient can change his or her "mind" about moving, the basal ganglia won't receive any novel stimuli. Ever. 

"The cerebellum smooths out movements, important and trivial ones alike, whereas the skeletomotor loop of the basal ganglia ensures that salient actions take priority over automatic, mundane ones. The nonmotor functions of the cerebellum and basal ganglia may similarly diverge with the cerebellum focusing on automatisms and the basal ganglia on matching motivation, thought, emotion, strategy, and movement to urgency and circumstance.  

The implications of this whole paragraph are HUGE.

We (people) are domesticated primates/animals, not wild free ones tuned to every nuance of our environment. Not that I'm not grateful for that. But it likely means not as much fresh input as might be desirable, from a basal ganglia standpoint. 

"The cerebellum associates sensory input with motor output, so that a set of inputs related to the body and the outside world - an entire sensory gestalt - becomes associated with a particular movement."

The cerebellum would totally turn us into robots if it could. 

"the basal ganglia associate self-generated actions with their consequences, biasing present and future selection of actions toward previously rewarding ones."

The basal ganglia operate on information that is already "old" by the time it reaches them. They are biased toward whatever worked before. I see Tim Conway banging his head against the wall in some Carol Burnett skit, having completely missed the doorway. Yet basal ganglia are our only way out of movement dilemmas, it seems. Movement bottle neck, for sure. 

Implications

So... what does this mean for us, as therapists? 

What does it mean as part of a neuromatrix model? 

What does it mean for our patients whose brains have "decided" not to let them move certain parts in certain ways, by dishing them "pain" if they try? 

What does it mean in terms of a painful experience of movement? 

By the sound of it, the critter brain is pretty much in charge of everything. Clearly (to me at least) therapy involves:
1. setting up a benign context, non-noceboic, containing only the clear desire to be of help

2. pain explanations to feed the cognitive parts of the human brain, which I see as desperate for answers, which get people thinking about their own brains
3. some sort of human primate social grooming (to provide innocuous and at the same time, novel interesting sensory input)

4. the patience to wait for improved output to emerge all on its own. From the critter brain itself.

Simple, but not easy...

See Barrett Dorko for more on "movement secondary to thought." 

"Ideomotion has two purposes - it expresses us, and it makes us comfortable."

Here is a short youtube video in which he explains how he treats the movement outflow bottleneck system, helps it change its "mind" about what kinds of movement it will permit. 

DORKO'S DIAMONDS 

YouTube series featuring Barrett Dorko PT

......

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 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." 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 10d: Conclusion 3: The brain's sense of "Self" can INclude missing parts, or EXclude actual parts, of the biological body Part 10e: The neural network that both comprises and moves "Self" is (only)modified by sensory experience
Part 11: We need a new conceptual brain model! Part 11b: Intro to a new conceptual nervous system Part 11c: Older brain models just don't cut it Part 11d: The NEW brain model!

Melzack & Katz, Pain. Part 12e Still awfully deep in basal ganglia

The paper, Pain

Most recent blogposts:

Part 12: Action! 12b: Examining the motor system, first pass. 12c: Motor output and nervous systems - where they EACH came from Part 12d... deeper and deeper into basal ganglia

                                          SEE ALL PREVIOUS BLOGPOSTS IN THIS SERIES LISTED AT THE END

We are deep into the inlet now, our little detour from examining Melzack and Katz's paper, sidetracked by the section to do with Action Neuromatrix. 

Source
Deep in the inlet

It's all very fascinating, but I think this will have to be our last day of detour; we'll have to turn around and go back, because I want to get back to the paper itself. 

Last look around at basal ganglia

Mason explains that basal ganglia are "choosers." So, if you dither around, can't make up your mind about something, maybe you can blame these little nuclei. 

She says, 

"Consider the clerk at a grocery store. As the clerk scans through one customer's items, a shopper asks, "Where could I find chicken broth?" Clerks, particularly novices, typically stop scanning items as they look up, think for a moment, and then tell the shopper the number of the aisle that contains soups and broths. Yet, continuing to scan grocery items while answering a question presents no true motoric challlenge. In other words, moving items past a scanner and speaking are both easy movements and since they employ non-overlapping musculature, nothing physical prevents the two movements from occurring simultaneously. Only because of the basal ganglia's influence do the two nonconflicting movements not occur together."

Then a big heading... OUR DEFAULT CONDITION IS TO DO NOTHING. 

"One can think of the basal ganglia as one large wet blanket, greatly hindering movement - or thought or emotion - until and unless the importance of an action reaches a critical level. When a candidate action becomes imperative, the basal ganglia release only the imperative action from suppression while maintaining the wet blanket over all other mutually exclusive actions. "

Huh. Sounds like the basal ganglia are there to be noise cancellers, so the rest of the brain can focus on whatever it finds the most salient signal at the time:

"Determining which action to allow out from under the basal ganglia's suppressive clamp depends a lot on circumstances. The action judged most salient based on present conditions and past experiences wins the competition, and the basal ganglia release this action from inhibition. Other potential actions, losing competitors to the winning action, remain suppressed by the basal ganglia. If circumstances change, and a different action becomes sufficiently imperative, the basal ganglia interrupt the current action and release the newly imperative action from inhibition."

SOURCE
Basal ganglia... Fascinating..

Wow.  They really are choosers. And this is all subcortical choosing going on, lest we forget.. critter brain is choosing.

Mason again:

"As we move through the world, the basal ganglia paces and sequences particular actions to fit with external conditions, our own judgements of urgency, and lessons learned from past actions."

Wow. That is very neuromatrix- sounding, isn't it? 

But wait, there's more! There is... habit formation! I think we are now into neurotag land, where Lorimer Moseley has shone a big light.

Mason again:
Big heading: GROUPING TOGETHER OFTEN REPEATED MOVEMENTS ENABLES SIMULTANEOUS ACTIONS

" The basal ganglia repeatedly select actions or series of movements with positive outcomes. When such a series of movements is selected over and over again, occurring in sequence time after time, the basal ganglia group those related movements together."

This sounds like musical instrument playing, or dance moves or martial arts or weight-training or yoga or any practiced skill. 
Sounds also like neurotag formation. 

Mason:

"Chunking of related and often repeated movements enables a series of movements to be relatively hard-wired together. Thus, chunking permits a sequence of movements to occur without the need for selecting each component movement ... once learned, chunked behaviour can easily be chunked with other behaviours.. [e.g., type a whole word on a computer as though it were one single action] ... instead of a long sequence of individual movements...  

Along with the advantages of chunking comes a disadvantage - once started, a chunk is difficult to interrupt. Once you start signing your name, it requires deliberate effort to stop in the middle. The difficulty in interrupting a chunk stems in part from the independence of that chunk from its outcome. In other words, we complete chunks regardless of whether they produce positive, neutral or negative results. Freeing chunks from contingencies enables us to easily perform complicated movements without focused thought and attention and allows people to achieve many of their goals automatically. However, dissociating actions from resulting outcomes also promotes completion of acts that may not always serve us well.  

The aggregation of basic chunks into more and more complicated chunks enables the assembly of complex behaviours. For example, washing hands forms one of the building blocks and combines with washing hair and many other washing and drying chunks to automate taking a shower. Such layered chunking allows action selection to work on loftier choices than would be possible in the absence of chunking. Thus one chooses between taking a shower and fixing breakfast rather than between supination or pronation of the wrist.  In sum, we perform many, if not most, of our daily activities by initiating packages of motor behaviour, initially formed into chunks by the basal ganglia." 

Recall the Orthinology yarn by Moseley. 

Mason finishes by noting that an experienced check-out clerk will be able to answer a question from a shopper and scan items at the same time, effortlessly. 

"Thus, the basal ganglia allow multi-tasking only when all but one task are performed by habit as chunks, freeing cortex to initiate nonroutine actions. When sufficient need or urgency arise, rote execution of a chunk is interrupted to support a "single-minded" action"

My basal ganglia get a real workout every time I have to learn a new thing on a computer. 

.....

So, that was just a short 'n quick detour - there is so much more about motor output to cover - where it comes from, more about how it's managed, what the hook-up details are, the chemistry involved - I didn't even look at those. 
But it's been fun. I found out what that space-ship looking thing is (kind of) about. It's not monolithic - there are many many nuclei involved, that should not have been called "ganglia" in the first place... the name, "basal" means they are directly underneath something else important in there, the white matter of the cerebral cortex (source). The bits comprising it change out once in awhile as more info trickles in.. for example, the amygdalae used to be grouped into BG, but aren't anymore, those kinds of details. I found a pretty nice bunch of online resources (see below) if anyone wants to continue on

But for now, it's time for me to turn around, head back to Melzack and Katz, and pick up where we left off. 

Heading back now

Further reading

Neuroscience online

Body movement and the brain 

Basal ganglia dysfunction

Neuroanatomy course book

......

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 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." 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 10d: Conclusion 3: The brain's sense of "Self" can INclude missing parts, or EXclude actual parts, of the biological body Part 10e: The neural network that both comprises and moves "Self" is (only)modified by sensory experience
Part 11: We need a new conceptual brain model! Part 11b: Intro to a new conceptual nervous system Part 11c: Older brain models just don't cut it Part 11d: The NEW brain model!

Melzack & Katz, Pain. Part 12d... deeper and deeper into basal ganglia

The paper, Pain

Most recent blogposts:

Part 12: Action! 12b: Examining the motor system, first pass. 12c: Motor output and nervous systems - where they EACH came from.

SEE ALL PREVIOUS BLOGPOSTS IN THIS SERIES LISTED AT THE END

OK, so we're on this detour right now through the motor system, having ended up here by examining Melzack's paper, Pain, and the section inside Beyond the Gate about (scroll down) the Action Neuromatrix.

Over the last few posts we've argued with Wolpert over movement versus mobility, and discussed how the nervous system evolved itself, noted that fish ancestors gave rise to pretty much everything, and left off with basal ganglia, which we'll continue with here, as written up by Peggy Mason, doing a whole pile of research on the raphe nuclei, important parts of the descending modulation system in critter brains/vertebrates. And she just happened to write the fascinating text from which I'm drawing the info on basal ganglia (and so much more). 

[I must thank my sister for turning me on to this text.]

So, here we are.... deep, deep, deep in the "heart" of the critter brain. Maybe the entire neuromatrix!
[I like how the basal ganglia look like a fancy hi-tech headset. Or an intergalactic spaceship from some Start Trek movie.]

SOURCE

Mason says, p.559:

"The striatum and pallidum are the core participants in circuits that adapt behavioral output to conditions with continually changing priorities and dangers. As introduced in Chapter 13, functional and connectional considerations have led to grouping forebrain and midbrain nuclei - the substantia nigra pars compacta, substantia nigra pars reticulata, and the subthalamic nucleus - together with the striatum and globus pallidus as the basal ganglia."

Well, now at least we know who the main players are! 

[The illustration I posted names other nuclei.. maybe not as relevant from Mason's perspective.]

"The GABAergic neurons of the pars reticulata spontaneously fire action potentials." - Wikipedia.

Well well. That does sound very intrinsic, and kind of stimulating. 

But wait!

"The two pallidal nuclei and the two nigral (pars compacta and pars reticulata) parts constitute a high-frequency autonomous pacemaker^[6] (see primate basal ganglia system#Pallido-nigral_set_and_pacemaker)" - Wikipedia

Whoa... the little engines that could. 

Mason continues: 

"These regions operate via parallel but interacting loops with the cortex and brainstem to influence motor, oculomotor, motivational, emotional, and cognitive components of behavior."

Melzack talks about "loops" in just about every paper. Just saying. 

Mason:

"Although they are intimately involved in motor function, the basal ganglia exert their effects indirectly through projections to motor control centers of the brainstem and even more indirectly through projections, via thalamus, to cortex, primarily motor and prefrontal cortices. Targets of basal ganglia output in turn control the motivation, affect, strategy, and initiation of self-generated actions. "

Targets.. hmmmn. 

Mason again: next, a heading..

THE CORE FUNCTION OF THE BASAL GANGLIA IS TO CHOOSE BETWEEN MUTUALLY EXCLUSIVE ACTIONS

"The striatum and pallidum are phylogenetically ancient structures, with the former present in the earliest vertebrates - think hagfish - suggesting that the original, and potentially still core, function of the striatopallidal system solves a problem that all animals face. The ubiquitous and fundamental problem resolved by the basal ganglia is that actions that use the same muscles differently simply cannot occur simultaneously. "

My bold: OK, now I'm getting super interested in this motor output system that has so much brain power attached, and always has. 

"A fish cannot swim to the left for food, to the right toward a mate, and forward to get further away from a predator circling behind. The fish has to choose one of these actions."

I.e., it has to "decide" what is going to become its signal out of its "noise"

"Similarly, we cannot turn left to go to a fruit stand, right toward a friend's apartment, and accelerate forward in case the speeding car behind does not slow down. Just as fish do, we must choose one of several, mutually exclusive actions. In fish, reptiles, birds, and mammals, including humans, striatopallidal circuits select and promote one action while suppressing competing actions. The process of choosing one action from many possible ones is termed action selection." 

Apparently, conditions like OCD and ADHD and Turette's indicate problems with this system.

Mason again:

"Although organized similarly in animals throughout the vertebrate tree, neurons and circuits of the basal ganglia achieve far greater complexity and vastly more connections in the cerebral cortex of mammals and especially in humans. The increase in basal ganglia complexity from fish to human reflects:

• a much more complex body plan - Humans control limb, digit, laryngeal, and facial muscles that fish, sharks, and snakes do not possess (yup, none of those play the piano) 

• More complex interactions with gravity and the physical environment on land than in sea (more stimulus to develop a humanantigravitysuit) 

• A larger behavioral repertoire. Fish swim this way and that, whereas humans crawl, swim, walk, hop jump, and skip as well as play guitar, yodel, and so on (some in high heels) 

• An enormously complex social structure in which individuals tailor their actions to specific persons or people  A child shares her favorite toy with a best friend but not with a stranger (primate troop safety and concept of "other")  

• The ability to learn from experience and match behavior to particular circumstances  An infant goes to pet the friendly cocker spaniel and unfamiliar pit bull alike whereas after acquiring some experience with dogs, she pets the friendly cocker spaniel and even the familiar pit bull, but walks away, hands in pockets, from the unfamiliar pit bull" (discernment) 

There is much more to come about basal ganglia. Looks like they are the little brains that operate the big brain. 

.........

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 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." 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 10d: Conclusion 3: The brain's sense of "Self" can INclude missing parts, or EXclude actual parts, of the biological body Part 10e: The neural network that both comprises and moves "Self" is (only)modified by sensory experience
Part 11: We need a new conceptual brain model! Part 11b: Intro to a new conceptual nervous system Part 11c: Older brain models just don't cut it Part 11d: The NEW brain model!