POSMODEV Who are we Main markers of the postural development Questions, definitions Central Coordination Disorder (C.C.D.).
Cerebral Palsy (C.P.) the Vojta concept More about reflex locomotion Fitting for C.P. children Documentation and training


MOTOR EDUCATION: MYTH OR REALITY...?

(by H. Lagache)


Summary:
Reflection about the postural development and the functional organization of motor patterns in a learning situation: the innate patrimony could remain, all along our life, the matrix from which emerges gradually an infinity of adaptative protocols enabling to control a lot of various corporal situations ...

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Physiotherapy is in permanent mutation, it becomes everyday enriched with new techniques, often comming from an initially empirical work, whose future depends on therapeutic results that they will be able to induce, as well as on their resistance to the critical analysis increasingly sharpened by the scientific knowledge.

Many researches put in obviousness the interactive character of the different functional registers of the central nervous system (CNS). During of the human development, these interactions can contribute to determine the anatomical configuration of the connexion device, that perpetually metamorphoses, as it was revealed by the theory of the selective stabilization. These interactions concern also the acquisition, then the exploitation of complex mental functions such as all those using abstraction (time - space structuring for instance).

In order to take better in account this notion of interactivity, many therapists imagined therapeutic protocols with a permanent research of addition and diversification of the input sources. Thus appeared many therapeutic proposals including the simultaneous recourse to different sensory sources (proprioceptive, auditive, optic, etc...), or seaching the "conscious realization" of a corporal situation by various means (mirror, language, relaxation, etc...) and hoping to activate a "motor learning" process with the aim of functional restoration. These proposals reveal the common ambition to use the corporal, sensory experience and the image of the body, as rehabilitation means.

We have now to wonder about the real efficiency probability of these various input flows: the notion of interaction means that all the components are complementary, but does not mean necessarily that all the factors are playing an equally important role. Is there a hierarchy of influence between a system as compared to an other system?... Have we to research a sequential logic in the progress of complex neurological patterns?...

The most eminent researchers develop about this topics different points of view, sometimes contradictory, from which the ordinary therapist has some difficulties to imagine the beginning of practical applications. However, it is not forbidden for the ordinary therapist to observe and to think on the basis of his own modest observations.

The following simple example strives to bring a small stone to the edifice of the comprehension by underlining the major role that seems to play the muscular proprioception in every neuro-motor function, and consequently in each therapeutic situation, independently of pathologies and of the interest that the therapist or the educator takes (or doesn't take) in this neuro-muscular component.

Imagine a young man wanting "to learn" how to hammer a nail in. The hand that holds the nail, and the whole upper limb on this side, are beginning a stabilizing action of this object; this action has a static character, while the limb that mobilizes the hammer is beginning a repetitious phasic movement (hammering movement). If this young man is right-handed, he holds the nail in his left hand and the hammer in his right hand, what leads to the uncertain hypothesis of a "specialization" according to which the phasic movement would be entrusted to the limb that is generally considered as the most "skilful" (right upper limb for a right-handed person, and vice versa), while the action of stabilization would be entrusted to the "less skilful" limb.

Furthermore, it is generally admitted that the vision is an essential way of "conscious realization" of a motor action. In this case, the motor action that our young man has to "realize" consists of finding and controling the best trajectory in the space for the hammer to the nail, what means, in fact, the motor activity of the right upper limb. This necessity is strengthened by the fact that the target (the nail), seized between the fingers of the left hand, is exactly at the extremity of the limb, while the length of the right upper limb (the "hammering" limb) is modified by the presence of the hammer. Moreover, the part of the hammer (that has to reach the nail) makes an angle of 90° with the handle, what modifies notably sensory data on the right side. As this young man realy wants to hammer his nail, in good logic, he would have to concentrate his optical system on ..... the hammer, and on the right limb holding the hammer. We easily imagine what would happen to the fingers of this poor boy's left hand, if he realy looks at the movement of his right hand, rather than at the nail...!

Why does looking at the target rather than at the moving corporal part does improve the coordination of this movement?

The answer comes rightly from this notion of interactivity. The problem, for the CNS, is to appreciate the distance between the target and the tool, to determine the best possible path for this tool, and to control it.

In this context, the CNS has got an immediately operational device that includes at least two essential components: the optical system, but also the muscular proprioceptive system that plays a fundamental role in the postural adjustment.

As the look is centered on the target, the hammer will be during a long part of the action out of the visual field, it comes only intermittently in the visual field and solicits then probably in priority the peripheral vision. Optic informations, from the retina, concerning this moving limb are therefore intermittent too, while the optical signal coming from the target is constant and concerns in priority the central vision. This confers to the target a status of permanent and stable reference in such a way that the nail becomes the point zero of the posturo-motor "measuring".
On the other hand, the boy has organized the totality of his initial posture in order to hold the nail. This initial posture, actively stabilized, already generates stark and durable proprioceptive inputs before beginning the "hammering" action; these data play for the CNS the role of a preliminary inventory before the following action. Inputs from the retina, and muscular proprioceptive inputs are closely coupled because retinal inputs are indissociable from proprioceptive inputs coming from the eyes muscles used to stabilize both eyes. Moreover, a large majority of proprioceptive informations comes from the rest of the body and especially from the most complex muscular groups, covering a lot of joints, that means muscles very receptive to the smallest postural modification, and that generates therefore the most important neuromuscular proprioceptive inputs: vertevral muscles.

If we simply analyze the postural situation of the boy before the "hammering action", we observe that this posture has no particularity linked to the future action; this posture could have been lived during thousand other anterior activities. The support polygon, is a triangle going from the hand, that holds the nail and leans on the workbench, to both feet; we are here finding a posture that has been largely exploited in the childhood, just before free walking, when the boy walked sideways along furniture. From these three supporting points, the musculature is now going to determine the path of the mobile upper limb that holds the hammer. In this initial posture, the upper part of the body constitutes a bow going from one hand to the other, and the future path of the tool is approximately the string of this bow. (fig. 1).

At this time, the CNS has no way of direct appreciation of this bow string, no direct means to determine the future path of the tool in the space; odds of conceptualization of a " motor project" are therefore practically null; but the CNS receives an abundant proprioceptive information from the bow itself. It is essentially through deformations of the bow during the movement that the CNS becomes able to regulate the necessary postural adaptation from the beginning of the motor action; this beginning of regulation, entirely automatic, implies no conscious activity. We can only think that a tiny part of the innumerable instantaneous readjustments occurring from the departure of the action, and probably managed by short and quick neuronal circuits, is consciously perceived, therefore a posteriori, thanks to the simultaneous activation of necessarily longer circuits.

This leads to consider that the regulation of the motor action, even in a new situation such as "learning", begins with an improvisation of the CNS on the basis of automatic already available patterns, activated by the initial postural configuration. Then appears this hypothesis: the vision (centering of the look onto the target) would have less the aim of contributing to guide directly the movement, than to catalyse a widened central processing of proprioceptive flows by activating a vaster central territory.

To summarize, there is a lot of preliminary postural references before the beginning of the action. These initial postural references are not specific of the action that is going to start (hammer the nail); very similar situations have been lived during the anterior ontogenese.

In our example, this support polygon has been tested for example during lateral walking along furnitures at the end of the first year of development, just before free walking (fig. 2). In this time, there was an other finality, the child acted to satisfy an environment appeal, but making this, he perceived and refines unconsciously the same postural automatisms that appear again today, in a new situation, enslaved to an other finality.

Beginning of the hammering movement:
a) the postural activity of the whole body may be compared to a child walking along furnitures and supporting on one upper limb before free walking; there is a support diagonal from the left hand to the right foot. Out of his global postural strategy, entirely automatic, will emerge the hammering movement; the fine adjustment of this movement is governed by the initial posture.
b) a great part of postural elements from the situation a) can be found again during free walking when the weight of the body is on the right leg, especially the axial rotation; there is no more support on the hand, that is partially compensated by the kinetic energy from both upper limbs and from the shoulder belt moving together.

In the present "learning" situation, the young man's attention is monopolized by the target to reach and he forgets his body; the exterior observer (the educator for example) may think opportune "to help him" by suggesting him to observe, to "think" of his own gesture, to favor a "conscious realization" of the movement, and to improve its precision... Is this educator's tendency coherent, as compared to the reality of unconscious automatic regulations that are playing here the most important role? We may wonder about this, if we analyze the postural mechanisms required for this action.

Indeed, from the beginning of the first "hammering" movement, with displacement in the space of the right upper limb, the balance of the posture would be broken without an immediate global adaptation that has to include:
Increasing supporting activity of the right lower limb (RLL) and the left upper limb (LUL), that means confirmation of the active support diagonal (fig. 2), that allows to launch the right upper limb (RUL, holding the hammer) to the target.
Finely differentiated rotation, almost isometric, of the whole vertevral axis conditioning the orientation of both belts: the shoulder belt is precisely placed in order to facilitate the movement of the RUL while the pelvic belt remains stable.
At the end of the RUL movement: braking of this limb with increasing support action of the left lower limb (LLL), weight lightening on the RLL, contact of the hammer on the target, that means short and very rapid inversion of the supporting diagonal. These operations suppose a series of postural micro-adjustments in the vertevral axis.

This very brief postural sequence includes the alternation of both supporting diagonals, the differentiated rotation, in minimal amplitude, of the vertevral axis with opposition of belts, the frontal transfer of the gravity center from one foot onto the other, the phasic (visible) coordinated movement of one upper limb in the space; it is an extremely complex neuromotor sequence, but it is for us something very familiar. All these postural elements have already been experienced, they are, in their architecture and their sequential organization, stemming from an essential locomotive pattern (fig. 3), that enabled for example a 4-5 months old child to stabilize his body, in ventral posture, to get one upper limb free for the grasping function.



This crossed pattern has later enabled, by displacing the supporting points at the extremity of the limbs, to discover the quadrupedic crossed locomotion, to stand up (that is a vertical quadrupedic locomotion, fig. 4), to walk sideways, then to walk freely.

Roots of this global postural pattern are diving in the first months of the ontogenesis, and beforehand in the phylogenesis since it appears precociously by all children whose postural development is normal. This pattern matured gradually in the course of the first year; it was regularly activated by needs of the relational life, by successive appeals; the child has exploited it in an infinity of situations, apparently different because they were enslaved to various finalities (orientation, consumption, locomotion) but their postural architecture was based on the same common fundamental elements: coordinate vertevral rotation, alternation of support diagonals, alternate lateral transfer of the gravity center, first induced by upper limbs, until the quasi-perfection of automatisms enabled the erected posture; then it was possible to lose the support activity at an extremity of the diagonal (upper limb), with considerable reduction of the support polygon at the size of a foot, that was free walking....

The same pattern would as well enable a future tennisman to acquire the "specific" gesture of the service, it could also enable a cycle champion, stabilizing his forearms on this so particular modern handlebar, to earn some precious seconds by the optimal exploitation of his oblique muscular chains thanks to this supporting points close to the elbows (the direct mechanical activation of the trunk and vertebral musculature, associated with the aerodynamic posture, contribute together to improve the muscular lower limb output). Everybody knows that the oblique orientation of the majority of our muscular fibers corresponds perfectly to this crossed fonction with rotation along a supporting diagonal.

The situations are various, the finalities of the active life are changing, the fundamental postural management is complex, but it looks like a series of improvisations of the CNS on a well known central theme (or pattern) , based on largely experienced elementary postural mechanisms .

When the boy is going to hammer for the first time his nail (initial learning stage), at each stage of the movement, his CNS gets new proprioceptive inputs favoring the immediate adjustment of the global posture and therefore of the present movement: the movement never finishes as it began, it finds its bearings, becomes more precise in the course of its progress.
The perception of the corporal bow induces the potential perception of its string, the movement emerges from the posture. Now only, it will perhaps be possible to conceptualize the movement.
This posturo-motor refinement is also favored by the immediate repetition of the movement, without interruption of the action, propitious to the spatio-temporal summation.
In the present case, the weight of the hammer is also a favorable element because its inertia plays the role of a resistance when the movement is starting, then its kinetic energy solicits a more important muscular braking at the end of the trajectory. It will contribute therefore to the recruitment of an increasing number of motor units and to the amplification of the input flow.

That necessitates a constant and very precise adaptation of muscular action all along the vertevral axis; these numerous successive and instantaneous micro-adjustments escape totally notice, there is here no conscious perception of these postural components, but without them the correct orientation of movements in the space is inconceivable.

When the gesture is well adequate, the visual control is almost superfluous; we are then tempted to tell that this gesture has been automated, but did it ever begin or stop to be automatic...?

Our posturo-motor development could therefore be modular: that means that the diversity of postures and movements acquired during the ontogenesis in order to construct the daily relational life (visible part of the iceberg), would be compatible with the persistence of an innate fundamental posturo-motor architecture; this functional basic structure (invisible part of the iceberg), linked to our muscular configuration, would be superficially restructured by the confrontation with physical conditions and with stimulations of the daily life, but would play nevertheless a determining role in the emergence of multiple locomotive and motor functionalities, and therefore, in the elaboration of our relational life with the world.

The combination of automatic fundamental postural elements into multiple synthesis would constitute therefore the principle of our functional evolution. The nervous system would work as an artist who creates an infinity of motives and nuances from a permanent and limited number of available fundamental colors on his paddle.

The young man of our observation is valid, that means with a healthy body and a healthy functional nervous system ; he has got therefore, potentially, an optimal posturo-motor adaptability, that will enable rapid "learning". All of the fundamental colors are available on the artist's paddle (the CNS), and his creative ingenuity (adaptability) is not compromised. But what happens when a pathologic process disturbs the CNS? What happens when a peripheral lesional process (that does not concern directly the CNS) imposes a compensation motor function, a kind of posturo-motor succedaneum, that provides the CNS, all along the functional life, with erroneous proprioceptive inputs?

These interrogations ask the problem of adequation of the therapeutic action with the postural reality of our patients with lesions and various aftereffects. It seems to be essential, in every therapy aiming to improve or restore the motor and postural function, to privilege a systematized solicitation of the proprioception because it constitutes the greatest deal of neuronal inputs. Muscular proprioceptive informations are permanent, they are coupled with the other afferences from the exteroception, interoception, retina, ears, labyrinth, etc... The influence of the muscular proprioception on the function and even on the development of the other input systems must be considered. That is the reason why the muscular proprioceptive system has to be the permanent and preferential tool of the physiotherapist.

The right usage of this very complex tool implies however the choice of adequate therapeutic means: for example, V. Vojta has shown how, to recruit neuronal circuits able to induce automatic postural readjustments, or to activate new motor units, the therapist has to play with the duration of the muscular contraction rather than with its intensity (the application of resistances, braking the movement, is a way to get that). This may justify the choice of an isometric long working, implying a specific therapeutic protocol.

The direction of the movement is an other interesting topic. The neuromuscular proprioceptive input from the motor activity plays a determining role in the perception of the kinetic trajectory of corporal segments. Now, the global proprioceptive perception, essentially unconscious, from the same muscular synergism differs depending on whether the former is isometric, isotonic or isokinetic; it differs also according to the spacial distribution of supporting points that determine the direction of the muscular traction (open chain or closed chain), it differs depending on whether these points are actively constituted or artificially given by the therapist.

Passing from a passive posture, given to the patient by the therapist, to an active posture including the active confirmation of supporting points, may already be considered as an argument of proprioceptive therapy, even before that the smallest movement appears, when the therapist has intentionally chosen the posture of the patient, to privilege some supporting points, and thus to activate the oriented traction of particular muscular elements.

The orientation and the possible conceptualization of movements that may then happen, are directly conditioned by the active control of the initial posture from which the movements emerge, and that determines the configuration and the direction of the segmental movements. The movement, independently of its finality, has to be understood as a succession of multiple postures, emerging one from the other.

The posturo-motor mechanisms simultaneously used to manageme postures and movements are a lot too complex and especially too global to be the subject of an intentional management that means of an essentially conscious regulation. Without denying the influence of elements such as optical afferences, psycho - sensory interactions often quoted to justify a therapeutic way based on the postural "conceptualization" by various means, this observation relativizes the interest of that "conceptulization" means. That underlines the necessity, during the therapy, to use therapeutic protocols based on the analysis of the postural automatisms, of their global organization, of their evolution in the course of the ontogenesis, of the modifications that they undergo at every period of the life when appears a pathological factor. A best comprehension of these fundamental automatisms contributes to orient the therapist to technical therapeutic ways where the systematic and planned solicitation of the proprioceptive system would have to be a permanent concern. The analysis of the global postural dynamics, considered as matrix of the gesture, leads us to envisage new evaluation and processing means: when the movement is deficient or deviating, it appears more important to work about the global posture that about a specific movement, the first conditioning the second.

This analysis opens also perspectives in the field of ergonomy: the global postural evaluation provides precious arguments for the daily installation of the handicapped person, as well if we are wanting more comfort as to improve the motor productivity.

By babies, the configuration of postural strategies reflects the degree of maturity, but also the quality of the development, as well in the mental or sensory field as in the motor field..

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Bibliography:

1 - Bullinger A: le rôle des flux sensoriels dans le développement tonicopostural du nourrisson; Masson, Motricité Cérébrale (1996)
2 - Changeux JP: l'homme neuronal, Paris, Fayard (1986)
3 - Lagache H: le concept Vojta; SPEK, Kinésithérapie ScientifiqueS N°366 (1997)
4 - lagache H: le mythe du clou; SPEK Kinésithérapie ScientifiqueS N°392 (1999)
5 - Redon-Zouiteni C, Roll JP, Lacert P: Reprogrammation posturale d'origine proprioceptive chez l'enfant infirme moteur cérébral;Masson, motricité Cérébrale 15-2 (1994)
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11 - Vojta V, Havel J: Utilisation of the inborn global patterns in the early treatment of neuromotor lesions; in Bottos M (ed) Neurological lesions in infancy. Liviana, Padova, pp 155-164 (1987)
12-Vojta Vaclav, Peters Annegret: das Vojta Prinzip;Spinger Verlag Berlin, Heidelberg, New York, London, Paris, Tokyo, Hong Kong (1997)
13 - Zeki Semir: A Vision of the Brain, Blackwell Scientific Publications, (1993)

POSMODEV Who are we Main markers of the postural development Questions, definitions Central Coordination Disorder (C.C.D.).
Cerebral Palsy (C.P.) the Vojta concept More about reflex locomotion Fitting for C.P. children Documentation and training









selective stabilization (Changeux and coll.):
The plasticity of the central nervous system is very important during the first months of life. Potentially available neurological itineraries for the transmission of impulse are, in this period, overabundant. A selection is gradually done , with degeneration of the few solicited connections, while the most used connections get their maturity, and take on the responsibility of various functions: that is the selective stabilization. This process offers a functional compensation appropriateness in case of neurological lesion; it decreases at the end of the first year, and that corresponds to a diminution of the central malleability.
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