Hippocampus, theta waves and movement VII

Vanderwolf wanted to sort out what would happen with direct brain stimulation as opposed to merely observing slow wave in conjunction with spontaneous behaviors.

Vanderwolf (p. 33) is careful to point out that:

"..the fact hippocampal rhythmical slow waves occur in close correlation with certain patterns of movement does not necessarily mean that hippocampal activity has a role in causing the movement. It is well recognized that correlation does not prove causation."

He goes on to say,

"It is apparent that some motor patterns, including the various forms of locomotion, head movements, spontaneous changes in posture, and manipulating objects with the forelimbs, are invariably accompanied by hippocampal rhythmical slow wave activity, while other motor patterns, including alert immobility, licking, biting, chewing, face-washing, and such gross motor patterns as the startle response and the writhing-stretching movements of giving birth, are generally accompanied by an irregular pattern of hippocampal activity. These hippocampo-behavior relations occur during both spontaneous behavior and the behavior elicited by hypothalamic stimulation. The two different classes of behavior cannot be distinguished on the basis of extent of muscular activity, degree of arousal, stress, or excitement and have no particular relation to the often stressed polarity of learning and instinct. How should all of this be interpreted and what should these classes of behavior be called?"

To me this is the crux of the matter, and why I'm busy reading this book. To continue:

"Animal behaviorists, following a proposal by Wallace Craig in 1918, often distinguish appetitive from consummatory behavior. Walking toward food is an appetitive behavior; eating the food, a consummatory behavior. Prior to Craig's suggestion, Charles Sherrington (1906) had suggested a distinction betwen precurrent reactions (similar to Craig's appetitive behavior) and consummatory reactions, stressing the dependence of the first type on distance receptors (vision, audition, olfaction) and of the second type on contact receptors (touch, taste). However, John Hughlings Jackson, an English neurologist writing well before either Sherrington or Craig, had suggested a continuum in the basis of motor control ranging from most voluntary to most automatic or reflexive... Consequently, I began to refer to behaviors consistently accompanied by hippocampal rhythmical slow wave as "voluntary" and behaviors not consistently accompanied by this wave form as "automatic." However, the attempt to apply Jacksonian terminology to hippocampal-behavioral relations was not welcomed."

Instead he categorized behaviors into Type I and Type II.
Here is the list:

Type I (slow wave hippocampal activity always present):
walking, running, swimming, rearing, jumping, digging, manipulating objects with forelimbs, isolated movements of head or of one limb, shifts of posture.
Related terms: voluntary, appetitive, instrumental, purposive, operant, or "theta" behavior.

Type II (irregular wave activity):
alert immobility in any posture, licking, chewing, chattering teeth, sneezing, startle response, vocalization, shivering, tremor, face-washing, scratching fur, pelvic thrusting, ejaculation, defecation, urination, piloerection.
Related terms: autonomic, reflexive, consummatory, respondent, "non-theta" behavior.


So, after all this investigating of this interesting material I don't think I'm any closer to knowing where ideomotor movement might fit, but at least I know more about hippocampal wave associated movement than I used to.

Hippocampus, theta waves and movement IV

In part III I brought some of the info from Vanderwolf's book to do with movement, types of movement, and their association with hippocampal wave function. On p. 16 he says:

".. in 1962 (we) had shown that rhythmical waves could occur in the thalamus and hippocampus slightly in advance of overt motor activity. ...I had no accurate means of determining the precise instant of movement onset and.. spontaneous movements do not have an abrupt onset. Spontaneous walking, for example, is usually preceded by small head movements and adjustments in posture (intention movements). What was need was an abrupt transition from complete immobility to vigorous gross movement of the type that is consistently accompanied by hippocampal waves."

To solve this problem he designed a box with a metal floor into which a rat could be placed and a small shock delivered to its feet, part of a training process teaching them to jump out of the box; i.e., shock was not part of the experimental design, just the jump-from-inside-the-box training.

"..a trained rat could be placed gently on the floor, standing on its hind legs. After a delay of several seconds during which the rat stood motionless, the hind legs would extend suddenly, propelling the rat to the top of the box. A movement-sensing device mounted on the box recorded the onset of this jump with an accuracy of a few milliseconds."

Vanderwolf found that rhythmical waves of 6-7 Hz could occur several seconds prior to the jump. Beginning about a second before the jump the frequency increased to 8-12 Hz, peaking at jump initiation, continuing until the rat landed on the "safe" shelf.

"The data from this experiment suggested that the hippocampus might have some role in both planning and the performance of a motor pattern. It also suggested a problem which subsequently became a major focus of my research. If the rhythmical waves of the hippocampus are related to motor activity, how is it possible that these waves can be present during relatively long intervals (several seconds) when a rat is absolutely motionless?"

Meanwhile, in a nearby lab the hippocampus of New Zealand white rabbits showed rhythmical activity being elicited with visual and auditory input only, no visible motor activity, something not noted in rats.

REM sleep presented another exception to the idea that hippocampal rhythmical activity was associated with movement, and was noted by Vanderwolf in the late 60's.

"The onset of REM sleep in a rat is always associated with an utter collapse of any pre-existing muscle tone. Thus, if a rat falls asleep in a crouched sitting posture, as they sometimes do, the onset of REM sleep is associated with the body slumping down limply on the floor. Despite this, bursts of muscular twitches occur periodically in the limbs, trunk, and especially in the vibrissae. Rhythmical slow waves occurred in the hippocampus throughout an episode of REM sleep, with higher frequency waves occurring during the muscular twitches than during the inter-twitch intervals. An interpretation of this curious phenomenon was suggested by research originating with Otto Pompeiano of the University of Pisa.It appears that brain motor systems generally are in a state of high activity during REM sleep but that overt expression of this activity is blocked by a powerful inhibition of spinal motor neurons and of reflex afferents to those neurons. Consequently, instead of running, jumping, etc. the animal lies limply on the floor, twitching slightly. The hippocampal record then is related to motor activity during REM sleep as well as during waking."

At this point Vanderwolf teamed with Bob Sainsbury and two students, Brian Bland and Ian Whishaw, to continue the work at U. of Western Ont.

Next: hippocampal slow waves, learning and instinctive behavior.

Hippocampus, theta waves and movement III

A description of the following rat behaviors and accompanying rhythms appears next.


Sleep to waking:

1. Sleep: neocortex waves went from low voltage fast activity to large amplitude, irregular slow waves.

2. Startle out of sleep with a noise: rat

"would leap to its feet, startled, its head up, eyes wide open, then stand motionless."

Large slow waves of the neocortex were replaced by low voltage higher frequency record (neocortical activation) but no rhythmical waves from hippocampus, instead a pattern of irregular waves with low amplitude.

From this Vanderwolf concluded that

"the rhythmical hippocampal waves had nothing to do with arousal or alerting; they were specifically related to a class of movements that did not include the startle response."

During movement:

3. In the waking rat: sensory stimuli generally elicited hippocampal rhythmical slow activity only if they also elicited a certain type of motor activity.

".. a great variety of visual, auditory, tactile and olfactory stimuli elicited both hippocampal rhythmical slow activity and a behavioral response that included head movements, stepping and locomotion."

4. Rats hung vertically by their front paws: No hippocampal activity was recorded while they just hung there, front paws clutched over the top of a vertical board.

"Rhythmical waves always appeared, however, when a rat pulled itself up, climbing to the top of the board."

Vanderwolf concluded that rhythmical hippocampal waves accompany certain phasic movements not static muscular exertion. Furthermore, maintenance of an immobile standing posture on two legs or four, was not associated with rhythmical slow hippocampal activity.


Grooming:

5. Grooming: Rat sits up on hind legs and uses front paws to rub its mouth, face, eyes and whiskers, followed by nibbling of own flanks, hind legs, abdomen. Movements are vigorous, but generally not accompanied by rhythmical hippocampal waves. By contrast, while resting, even just a small movement of one forepaw was regularly accompanied by rhythmical hippocampal waves.

Conclusion: two qualitatively distinct classes of behavior: one accompanied by waves and one not.

6. Grooming: occasional bursts of clear rhythmical waves lasting a second or two at most, occurred during long grooming sessions. They were accompanied by changes in posture, transitions from the rat paying attention to/grooming one area of the body, to paying attention to/grooming another area.

Conclusion: rat grooming behavior consists of two kinds of movement, 1) stereotyped licking, biting fur, rubbing of forepaws over face, without hippocampal slow wave; 2) changes in posture, accompanied by rhythmical slow activity in the hippocampus.

7. Grooming behavior, plus startle: Two possible reactions: rat becomes immobile (freezing behavior) without hippocampal slow wave accompaniment, however, if head movements or locomotion were chosen by the rat, rhythmical waves would appear.


Eating and drinking:

8. Approach to food, snatching it, running off with it: continuous rhythmical waves were recorded.

9. During chewing and handling of food with forepaws: Rhythmical hippocampal activity was present at the onset of eating a large food pellet, but as the pellet got smaller so did the hippocampal activity.

10. Sniffing behavior: vigorous sniffs with small head movements - no associated slow rhythmical wave from hippocampus associated.

11. Approach to/retreat from water dish was accompanied by rhythmical hippocampal waves but not the act of drinking itself.


Exploratory:
12. Rhythmical hippocampal waves were found to have no specific relation to exploratory behavior in general sense. On the other hand, changing posture of head while eating or changing posture while grooming are well-practiced and are accompanied by slow wave activity.

Next, Vanderwolf looked deeper at premotor activity.

Hippocampus, theta waves and movement II

The first problem Vanderwolf tackled was to get a clear reading, using rats. Finally he placed one electrode "near the surface of the alveus or in the stratum oriens and a second electrode in the vicinity of the hippocampal fissure." These are small bits of hippocampal gross anatomy. He then got wave potentials that occurred in opposite phase and that were easy to distinguish from neocortical waves.

He says:

"When, at last, adequate slow wave signals from the hippocampus were recorded, their relation to behavior became very obvious. Gross movements such as walking, struggling to escape from my hand, or rearing up on the hind legs were invariably accompanied by rhythmical potentials potentials of about 8-9 Hz but a more irregular pattern punctuated at irregular intervals by large spike-like potentials (sharp waves), occurred whenever the rat stood still. However, it also became apparent that a number of smaller movements such as turning the head, changing posture while resting, or moving a forepaw in isolation, were also reliably accompanied by rhythmical waves but both the amplitude and frequency (6-7 Hz) of these waves was less than it was during walking or struggling."

This information was obtained on rats, but humans and rats share mammalian brain structures. Walking sounds like a good thing to do for the hippocampus - make big waves so the 10,000 new baby neurons that form in there every day get some big wave stimulation.

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."

.............................



A BRIEF INTERLUDE
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.)