Tuesday, December 18, 2007

Rhythms of the Brain: Part III: Ideomotion?

By happy circumstance I found a good chunk of Buzsáki's book online this morning, which makes it easier for me to point the reader to the appropriate section which is p.18-22. Note the picture on p. 20 of the book. It depicts a time line measured in decades, between 1930 and 2000, and the various hypotheses of the behavioral correlates (kinds of movement or observable output) of hippocampal theta oscillations as they arose. To the right and left of the time line are photos of his two mentors, each of whom had their favored hypothesis based on impeccable reasoning and found themselves in seemingly opposing camps.

There is also "Oscillatory Heritage of the Grastyán School", which can be accessed by clicking on the instruction "open entire document", (in which the same picture appears on p. 136). and "Theta Rhythm of Navigation: Link Between Path Integration and Landmark Navigation, Episodic and Semantic Memory".

This material provides enticing clues about relationships among memory, movement, and theta oscillation. They are connected somehow, but apparently no one has been able to say exactly how, in 7 decades. One gets the impression that Buzsáki has spent his whole life trying to reconcile these two views into a third, sublating view.

1. The predominant theory linking the hippocampus and its theta oscillations to movement comes from Cornelius Vanderwolf, who was an advisor of Buzsáki's:

"theta occurs only during intentional or voluntary movement, as opposed to immobility and “involuntary”, i.e., stereotypic activity"

2. Buzsáki himself leans toward his original mentor, Endre Grastyán's idea:
theta is "orienting reflex, searching for stimulus with significance to subject"

From the first paper p. 135, and of interest to me because physical therapy is about restoration of functional movement, is this quote:

"Despite seven decades of hard work on rabbits, rats, mice, gerbils, guinea pigs, sheep, cats, dogs, old world monkeys, chimpanzees and humans by outstanding colleagues, to date, there is no widely agreed term that would unequivocally describe behavioral correlate(s) of this prominent brain rhythm. By exclusion, the only firm message that can be safely concluded from this brief summary is that in an immobile animal no theta is present, provided that no changes occur in the environment, and the animal is not “thinking”....
Processing environmental inputs requires “attention”, and so does intentional movement. With the introduction of the term “voluntary”, theta oscillation research unintentionally entered the territory of “intentionality,” a label that refers to the “substance” of all subjective mental activity (Dennett, 1987). Thus, an inescapable deduction from the behavior-brain correlation approach is that the “will” plays a critical role in theta generation. An alternative, and perhaps more sober, conclusion is that our behavioral-cognitive terms are simply working hypothetical constructs that do not necessarily correspond to any given brain mechanism."

My bold.

I confess not knowing the scientific background of either of these august hypotheses or what led to their two solitudes, but I did note that missing entirely from the debate (as near as I can tell), and certainly from the picture, has been any recognition of something called ideomotion, defined medically as
"Muscular movement executed under the influence of a dominant idea, being practically automatic and not volitional."


to discuss Ideomotion

That "not volitional" part could be important, because if, as Vanderwolf says, theta oscillation is present in only "voluntary movement", then presumably it would be absent in ideomotion according to the definition of ideomotion. However, in ideomotion, movement is occurring, although no "thought" in terms of conscious motor command or inhibition is directly involved.

Then there is this: immobilized animals do not produce any theta oscillation ("in an immobile animal no theta is present, provided that no changes occur in the environment, and the animal is not “thinking”"). Certainly in ideomotion movement occurs, but it's hard to say if "thinking" does... Certainly people who explore this movement are wide awake and perceiving, but their bodies are moving them, it is not they who are moving their bodies: yet they can interrupt the ideomotion if they choose. Is "perceiving" usually considered as "thinking"? What about the zen states of alert no-thought?

What about the proviso contained in this sentence:
"By exclusion, the only firm message that can be safely concluded from this brief summary is that in an immobile animal no theta is present, provided that
- no changes occur in the environment, and
- the animal is not “thinking

... what exactly does "thinking" mean? Attending? Being brought out of a reverie by an exteroceptive (environmental) distraction?

What if there actually existed a type of "no-thinking" "movement"? Would theta oscillation be present then I wonder? I'd love to know some day.

If ideomotion were entirely volitional, it wouldn't likely have become an adjective modifying a noun, "effect" as in "ideomotor effect". There would be no such "effect" if all the parts of the brain were simultaneously aware of the movement, and if the movement were being generated by conscious parts of the brain rather than non-conscious parts or at least slightly less conscious parts.

For more about all of this, see the essay by Barrett Dorko, called Without Volition. He has learned how to teach this form of movement, which seems contradictory at first - how can one consciously learn to produce movement that is non-conscious? Dorko says, it's already in there, in everyone. This is consistent with neuroscience, embryology, evolution, etc. - all of which say movement precedes sensation. A study has been conducted and others are being conducted to test the effectiveness of this approach on pain perception.

No learning is involved, just un-learning - of conscious inhibition of this deeper kind of "organism" movement.

The main "ideas" delivered to those wishing to experience ideomotion are:

a) It exists
b) It is possible to stop inhibiting this movement. Inhibition, after all, requires muscular contraction and can therefore be a waste of energy, or can create nociceptive irritation, may have become unconscious (as opposed to nonconscious).
c) One simply chooses to "go inside" and wait for a brief period of time for it to emerge,
d) One sits with eyes closed and waits for a few seconds. It starts up, all by itself (well, usually gravity helps a little), then one allows it to proceed without interference.

It emerges as though one never didn't know how it was "done". Slightly differently for each individual. Unique like a fingerprint, a movement output "signature". Also like fingerprints, different for each person but with recognizable characteristics in common, certain qualities that distinguish ideomotion from other kinds of movement.

Usually eyes are closed (they also tend to roll up) which seems to help focus to be retained within. The immediate first person experience of this form of movement is effortlessness, ease, surprise (usually pleasant), softening, and a feeling of spreading warmth. Dorko calls these "characteristics of correction", a throwback perhaps to his manual therapist past. Perhaps they should be thought of as characteristics of self-correction.

From the "observer" point of view, the movement looks eerie and beautiful at once, rather sea-creature-esque, long slow loops and circular patterns that come from the main vertical axis of the body. But don't "have" to..

What I like from the therapist perspective is that no physical effort is required from me, either, just light contact for the first few seconds, to help the patient orientate to something exteroceptive, however mild, for reassurance mostly. Simultaneously they are asked to go "inside" themselves; for many, it will be their first time consciously dropping their own conscious control of motor output in the presence of another.

So what role am I playing? Someone who goes deepwater-diving for the very first time will experience unfamiliarity, arousal, some anxiety, a need to have contact with someone who will stay on the vessel and handle the oxygen hoses, provide a tug line through which the diver can signal any problem they may be having. The all-important trust factor must be present. With any "first experience", human primates usually require accompaniment from someone else who's "been there" before and can reassure. My role is the same as ever, to construct and maintain a treatment "crucible" in which the patient can change him or herself.

Next to no technical expertise is actually involved. The movement is natural, easy to experience (because it's there anyway, all along), more preferable to feel than tension, and can rapidly become a familiar and reliable way to drop tension and discomfort - just by letting it happen. The sense of this is, "Ah yes, this is how my body really moves, once I let it.""Ah yes, this feels like "me"." "How nice to finally feel what my physicality and moving really feel like."

Back to Buzsáki and theta oscillation

The Grastyán definition of theta oscillation and the movement associated with it, sounds like it could be ideomotor movement:

What if the "orienting reflex, searching for stimulus with significance to subject" consisted of a nervous system or portion thereof, suddenly deprived of and looking for its own familiar input, i.e., conscious command of voluntary movement?

What if this 'inputter' part of the brain had an heretofore unused ability to stop issuing commands, withhold them, and take itself off line for awhile? Stop inhibiting? Inhibit itself instead?

What sort of "movement" might be in there, completely capable of inhabiting and operating, by itself, the macroscopic motor system? Unencumbered by human wishes, wants, and dictates? Ordinary internal chatter?

All that is apparent is that in that long list of types of movements on page 136 of the "Oscillatory Heritage of the Grastyán School" article, and page 20 of the book, ideomotion is notably absent. William James thought about and discussed it at one time (along with nearly everything else in existence in his day it would seem), and it was first defined by William Carpenter in 1852. It's been around for quite awhile. Maybe it was assumed to be one of those "behavioral-cognitive terms" that "are simply working hypothetical constructs that do not necessarily correspond to any given brain mechanism." Maybe it was simply overlooked, or missed completely, too obscure, too bogged down by the strange Victorian company it kept in its early days. To be fair, it never exactly achieved household familiarity.

Perhaps however, someday someone will have a look sometime to see if the movement known and defined as "ideomotion", might or might not have something to do with orienting behavior, memory, theta oscillation, non-voluntary movement.. all those tantalizing bits about which there has been disagreement, for over 7 decades of hippocampus research. Maybe someday, someone who knows how, will be able to untangle the "concept" of ideomotion from its "mechanism" (two different things as discussed in Part II), differentiate substrate from that which operates upon said substrate (.. maybe just some other substrate.)

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