Mechanical control vs CNS stimulation

mike weber · Jun 8, 2010

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Hi Folks Ive been thinking again............

Over the last few months we have been discussing leg stiffness and CNS control of knee, hip and ankle flexion and extension moments to control the leg stiffness. This change may or may not have an effect on other joint movement ie STJ pronation and supination moments which was the basis of the Does the tibia drive the foot or does the foot drive the tibia thread

I´ve been doing some reading about Proprioception in another thread.

Here websters online Dictionary take on Propriception

Definition: Proprioception

Part of Speech Definition
Noun 1. The ability to sense the position and location and orientation and movement of the body and its parts.[Wordnet].
Source: WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.

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Date "Proprioception" was first used in popular English literature: sometime before 1948. (references)

Extended Definition: Proprioception

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Proprioception

The cerebellum is largely responsible for coordinating the unconscious aspects of proprioception.
Proprioception (pronounced /ˌproʊpriːəˈsɛpʃən/ PRO-pree-o-SEP-shun); from Latin proprius, meaning "one's own" and perception) is the sense of the relative position of neighbouring parts of the body. Unlike the six exteroceptive senses (sight, taste, smell, touch, hearing, and balance) by which we perceive the outside world, and interoceptive senses, by which we perceive the pain and the stretching of internal organs, proprioception is a third distinct sensory modality that provides feedback solely on the status of the body internally. It is the sense that indicates whether the body is moving with required effort, as well as where the various parts of the body are located in relation to each other.

Tests for Proprioception
In domestic animals, there are a number of relatively specific tests of the subjects ability to propriorecept, these are used in the diagnosis of neurological disorders. These tests include the visual and tactile placing reflexes[1].

History of Study
The position-movement sensation was originally described in 1557 by Julius Caesar Scaliger as a 'sense of locomotion'. Much later in 1826 Charles Bell expounded the idea of a 'muscle sense' and this is credited with being one of the first physiologic feedback mechanisms. Bell's idea was that commands were being carried from the brain to the muscles, and that reports on the muscle's condition would be sent in the reverse direction. Later, in 1880, Henry Charlton Bastian suggested 'kinaesthesia' instead of 'muscle sense' on the basis that some of the afferent information (back to the brain) was coming from other structures including tendons, joints, skin, and muscle. In 1889, Alfred Goldscheider suggested a classification of kinaesthesia into 3 types: muscle, tendon, and articular sensitivity.

In 1906, Charles Scott Sherrington published a landmark work which introduced the terms 'proprioception', 'interoception', and 'exteroception'. The 'exteroceptors' were the organs responsible for information from outside the body such as the eyes, ears, mouth, and skin. The interoceptors then gave information about the internal organs, while 'proprioception' was awareness of movement derived from muscular, tendon, and articular sources. Such a system of classification has kept physiologists and anatomists searching for specialised nerve endings which transmit data on joint capsule and muscle tension (such as muscle spindles and Pacini corpuscles).

Proprioception vs. kinesthesia
Kinesthesia is another term that is often used interchangeably with proprioception. Some differentiate the kinesthetic sense from proprioception by excluding the sense of equilibrium or balance from kinesthesia. An inner ear infection, for example, might degrade the sense of balance. This would degrade the proprioceptive sense, but not the kinesthetic sense. The infected person would be able to walk, but only by using the sense of sight to maintain balance; the person would be unable to walk with eyes closed.

Proprioception and kinaesthesia are seen as interrelated and there is considerable disagreement regarding the definition of these terms. Some of this difficulty stems from Sherrington's original description of joint position sense (or the ability to determine where a particular body part exactly is in space) and kinaesthesia (or the sensation that the body part has moved) under a more general heading of proprioception. Clinical aspects of proprioception are measured in tests that measure a subject's ability to detect an externally imposed passive movement, or the ability to reposition a joint to a predetermined position. Often it is assumed that the ability of one of these aspects will be related to another; unfortunately, experimental evidence suggests there is no strong relation between these two aspects. This suggests that, while these components may well be related in a cognitive manner, they seem to be separate physiologically.

Much of the foregoing work is dependent on the notion that proprioception is essentially a feedback mechanism; that is, the body moves (or is moved) and then the information about this is returned to the brain, whereby subsequent adjustments could be made. More recent work into the mechanism of ankle sprains suggests that the role of reflexes may be more limited due to their long latencies (even at the spinal cord level) as ankle sprain events occur in perhaps 100msec or less. Accordingly, a model has been proposed to include a 'feedforward' component of proprioception where the subject will also have central information about the body's position prior to attaining it.

Kinesthesia is a key component in muscle memory and hand-eye coordination, and training can improve this sense (see blind contour drawing). The ability to swing a golf club or to catch a ball requires a finely-tuned sense of the position of the joints. This sense needs to become automatic through training to enable a person to concentrate on other aspects of performance, such as maintaining motivation or seeing where other people are.

Basis of proprioceptive sense
The inititation of proprioception is the activation of a proprioreceptor in the periphery[2] The proprioceptive sense is believed to be composed of information from sensory neurons located in the inner ear (motion and orientation) and in the stretch receptors located in the muscles and the joint-supporting ligaments (stance). There are specific nerve receptors for this form of perception termed "proprioceptors", just as there are specific receptors for pressure, light, temperature, sound, and other sensory experiences. Proprioreceptors are sometimes known as adequate stimuli receptors.

Although it was known that finger kinesthesia relies on skin sensation, recent research has found that kinesthesia-based haptic perception strongly relies on the forces experienced during touch.[3] This research allows the creation of "virtual", illusory haptic shapes with different perceived qualities.[4]

Applications

Law enforcement
Proprioception is tested by American police officers using the field sobriety test where the subject is required to touch his or her nose with eyes closed. People with normal proprioception may make an error of no more than 20 millimetres. People suffering from impaired proprioception (a symptom of moderate to severe alcohol intoxication) fail this test due to difficulty locating their limbs in space relative to their noses.

Learning
Proprioception is what allows someone to learn to walk in complete darkness without losing balance. During the learning of any new skill, sport, or art, it is usually necessary to become familiar with some proprioceptive tasks specific to that activity. Without the appropriate integration of proprioceptive input, an artist would not be able to brush paint onto a canvas without looking at the hand as it moved the brush over the canvas; it would be impossible to drive an automobile because a motorist would not be able to steer or use the foot pedals while looking at the road ahead; a person could not touch type or perform ballet; and people would not even be able to walk without watching where they put their feet.

Oliver Sacks once reported the case of a young woman who lost her proprioception due to a viral infection of her spinal cord.[5] At first she was not able to move properly at all or even control her tone of voice (as voice modulation is primarily proprioceptive). Later she relearned by using her sight (watching her feet) and vestibulum (or inner ear) only for movement while using hearing to judge voice modulation. She eventually acquired a stiff and slow movement and nearly normal speech, which is believed to be the best possible in the absence of this sense. She could not judge effort involved in picking up objects and would grip them painfully to be sure she didn't drop them.

Training
The proprioceptive sense can be sharpened through study of many disciplines. The Alexander Technique uses the study of movement to enhance kinesthetic judgment of effort and location. Juggling trains reaction time, spatial location, and efficient movement. Standing on a wobble board or balance board is often used to retrain or increase proprioception abilities, particularly as physical therapy for ankle or knee injuries. Standing on one leg (stork standing) and various other body-position challenges are also used in such disciplines as Yoga or Wing Chun. In addition, the slow, focused movements of Tai Chi practice provide an environment whereby the proprioceptive information being fed back to the brain stimulates an intense, dynamic "listening environment" to further enhance mind / body integration. Several studies have shown that the efficacy of these types of training is challenged by closing the eyes, because the eyes give invaluable feedback to establishing the moment-to-moment information of balance. There are even specific devices designed for proprioception training, such as the Proprioceptor system, which consists of shoes with specially designed balls on the soles to make athletes work harder to balance. [6]

Impairment
Apparently, temporary loss or impairment of proprioception may happen periodically during growth, mostly during adolescence. Growth that might also influence this would be large increases or drops in bodyweight/size due to fluctuations of fat (liposuction, rapid fat loss, rapid fat gain) and muscle content (bodybuilding, anabolic steroids, catabolisis/starvation). It can also occur to those who gain new levels of flexibility, stretching, and contortion. A limb's being in a new range of motion never experienced (or at least, not for a long time since youth perhaps) can disrupt one's sense of location of that limb. Possible experiences include these: suddenly feeling that feet or legs are missing from one's mental self-image; needing to look down at one's limbs to be sure they are still there; and falling down while walking, especially when attention is focused upon something other than the act of walking.

Proprioception is occasionally impaired spontaneously, especially when one is tired. One's body may appear too large or too small, or parts of the body may appear distorted in size. Similar effects can sometimes occur during epilepsy or migraine auras. These effects are presumed to arise from abnormal stimulation of the part of the parietal cortex of the brain involved with integrating information from different parts of the body.[7]

Proprioceptive illusions can also be induced, such as the Pinocchio illusion.

The proprioceptive sense is often unnoticed because humans will adapt to a continuously-present stimulus; this is called habituation, desensitization, or adaptation. The effect is that proprioceptive sensory impressions disappear, just as a scent can disappear over time. One practical advantage of this is that unnoticed actions or sensation continue in the background while an individual's attention can move to another concern. The Alexander Technique addresses these issues.

People who have a limb amputated may still have a confused sense of that limb existence on their body, known as phantom limb syndrome. Phantom sensations can occur as passive proprioceptive sensations of the limb's presence, or more active sensations such as perceived movement, pressure, pain, itching, or temperature. The etiology of the phantom limb phenomenon was disputed in 2006, but some consensus existed in favour of neurological (e.g. neural signal bleed across a preexisting sensory map, as posited by V.S. Ramachandran) over psychological explanations. Phantom sensations and phantom pain may also occur after the removal of body parts other than the limbs, such as after amputation of the breast, extraction of a tooth (phantom tooth pain), or removal of an eye (phantom eye syndrome).

Temporary impairment of proprioception has also been known to occur from an overdose of vitamin B6 (pyridoxine and pyridoxamine). Most of the impaired function returns to normal shortly after the intake of vitamins returns to normal. Impairment can also be caused by cytotoxic factors such as chemotherapy.

It has been proposed that even common tinnitus and the attendant hearing frequency-gaps masked by the perceived sounds may cause erroneous proprioceptive information to the balance and comprehension centers of the brain, precipitating mild confusion.

Proprioception is permanently impaired in patients who suffer from joint hypermobility or Ehlers-Danlos Syndrome (a genetic condition that results in weak connective tissue throughout the body). It can also be permanently impaired from viral infections as reported by Sacks. The catastrophic effect of major proprioceptive loss is reviewed by Robles-De-La-Torre (2006).[8]

References
Introduction to Neurology, 2nd Edition 1976, A.C.Palmer, Blackwell Scientific, Oxford
Sherrington C.S., Brain 29:467-485,1907 http://brain.oxfordjournals.org/cgi/reprint/29/4/467
Robles-De-La-Torre G, Hayward V (2001). "Force can overcome object geometry in the perception of shape through active touch". Nature 412 (6845): 445-8. PMID 11473320.
the MIT Technology Review article "The Cutting Edge of Haptics"
Sacks, O. The Disembodied Lady, in The Man Who Mistook His Wife for a Hat and his autobiographical case study A Leg To Stand On.
The Proprioceptor System
Ehrsson H, Kito T, Sadato N, Passingham R, Naito E (2005). "Neural substrate of body size: illusory feeling of shrinking of the waist". PLoS Biol. 3 (12): e412. PMID 16336049.
Robles-De-La-Torre G. The Importance of the Sense of Touch in Virtual and Real Environments. IEEE Multimedia 13(3), Special issue on Haptic User Interfaces for Multimedia Systems, pp. 24–30 (2006).
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If we put aside the foot type and "Proprioception" insole arguement as it´s been done to death.

What go me thinking from the Websters info is that Proprioception can be learned. I also read the paper listed below which discusses nerve arrangement on the feet compaired to the hand. Which has got me thinking it there something to this....

In the Leg stiffness thread we discussed CNS stimulation from different surface stiffness and it´s effects on leg stiffness through muscle contraction and thereafter joint motion.

So ok if we use a device say a medial Skive we will look to by using an Orthotic reaction force (ORF) cause an extenal STJ supination moment, which may or may not cause STJ supination.

Will we then be changing the bodies position in space, which would lead to a "Proprioception effect", which can be learned ? Therefore muscle work to hold the body in it´s new position, these muscle contraction lead to joint motion, different from before treatment, which leads to changes in joint motions ?

Hope that makes sense, I´m bouncing some ideas around. Thinking out loud .

Craig Payne · Jun 8, 2010

Re: MMechanical control v´s CNS stimulation

m weber said: ↑

So ok if we use a device say a medial Skive we will look to by using an Orthotic reaction force (ORF) cause an extenal STJ supination moment, which may or may not cause STJ supination.

Will we then be changing the bodies position in space, which would lead to a "Proprioception effect", which can be learned ? Therefore muscle work to hold the body in it´s new position, these muscle contraction lead to joint motion, different from before treatment, which leads to changes in joint motions ?
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But, thats not proprioception - that could happen by an exteroceptive pathway.

That was my big issue in previous threads on the propriceptive effects of orthotics .... what can an orthotic do in that regard ? ..... it can change loading on the plantar mechanoreceptors and that is some additional information the CNS can use to activate muscles etc ... but that is NOT proprioception, as this is happening by an exteroceptive pathway.

That does not mean it actually happens and orthotics can and do work that way.

We tested 3 inverted foot orthotics in 3 different sensory conditions (rough surface, normal surface, iced foot) and got exactly the same kinematic response for frontal plane calc movement .. ie the effect on rearfoot motion was all mechanical (we will publish it one day)

Admin2 · Jun 8, 2010

Related threads:
Direct Mechanical vs. Neuromotor Effects of Foot Orthoses
Sensory effects of foot orthoses
Other threads tagged with neurophysiological

mike weber · Jun 8, 2010

Re: MMechanical control v´s CNS stimulation

Craig Payne said: ↑

But, thats not proprioception - that could happen by an exteroceptive pathway.

That was my big issue in previous threads on the propriceptive effects of orthotics .... what can an orthotic do in that regard ? ..... it can change loading on the plantar mechanoreceptors and that is some additional information the CNS can use to activate muscles etc ... but that is NOT proprioception, as this is happening by an exteroceptive pathway.

That does not mean it actually happens and orthotics can and do work that way.

We tested 3 inverted foot orthotics in 3 different sensory conditions (rough surface, normal surface, iced foot) and got exactly the same kinematic response for frontal plane calc movement .. ie the effect on rearfoot motion was all mechanical (we will publish it one day)
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I guess thats why I put it "Proprioception effect", but exteroceptor pathway sounds good to me, look forward to reading the paper.

Do you believe with enough "constant" change in information, a change caused by a stimulation of the exteroceptor pathway can cause a learned motion pathway. ie if stimulation occurs for long enough there are gait changes if we discuss orthosis.

Kevin Kirby · Jun 8, 2010

I don't think this neurological response to foot orthoses necessarily needs to be "learned" once the individual has learned to walk efficiently (probably by the age of 5). This is due to the fact that the individual's central nervous system (CNS) has already developed the capacity to alter the efferent output to their lower extremity muscles in a coordinated and efficient manner in order to keep the individual's center of mass balanced between their feet during standing and walking and allow the individual to remain upright.

Therefore, when a foot orthosis is designed with a medial heel skive, for example, that creates an external subtalar joint (STJ) supination moment, that individual's CNS must "decide" whether to allow the STJ to supinate, how much it will allow it to supinate, or. instead will stabilize the STJ against supination motion or even make the STJ pronate in response to the medial heel skive. There is a common misconception among podiatrists that simply adding a varus or valgus wedge to an orthosis will cause the foot to invert or evert in the direction of the wedging, forgetting that the CNS has a huge controlling effect on this STJ motion/lack of motion, regardless of the shape of the wedge. These concepts need to be understood by all podiatrists.

In order to clarify my thoughts further for, here is an excerpt from a Precision Intricast Newsletter I wrote on this same subject in October 2009:

DIRECT MECHANICAL AND NEUROMOTOR EFFECTS OF FOOT ORTHOSES

October 2009

by Kevin A. Kirby, Dpm

...............................Therefore, taking the above into consideration, the two main effects that foot orthoses have on the human locomotor system by their action of altering the magnitudes, temporal patterns and locations of GRF acting on the plantar foot are the direct mechanical effect of foot orthoses and the neuromotor effect of foot orthoses. The direct mechanical effect of foot orthoses is defined as the kinetic and kinematic effect on the foot and lower extremity that is caused by the change in the location, magnitude and temporal patterns of ground reaction forces that result from direct mechanical contact of the orthosis with the plantar foot. The neuromotor effect of foot orthoses is defined as the kinetic and kinematic effect on the foot and lower extremity that is caused by changes in sensory input to the CNS from the mechanical effects of the orthosis on the plantar foot that results from alterations in the magnitudes and temporal patterns of motor stimuli from the CNS to the muscles of the foot and lower extremity. The afferent inputs into the CNS that may lead to the changes may come from sensory organs within the skin, joints, muscles, tendons, eyes, inner ears or other areas of the body.

An example of the direct mechanical effect of foot orthoses is when an orthosis is designed with a relatively high medial longitudinal arch (MLA) and with a medial heel skive in the heel cup to increase the plantar force on the MLA and on the medial aspect of the plantar heel so that the MLA remains higher and the subtalar joint (STJ) supinates more during standing, walking or running. In other words, the increased pushing force from the orthosis in the MLA and medial heel cup onto the plantar foot causes a direct change in the joint position and/or joint motion of the foot and lower extremity during weightbearing activities that is in the same direction of the pushing force (Fig. 1).

Alternately, an example of the neuromotor effect of foot orthoses is when an orthosis is designed with a high MLA and a large medial heel skive but, instead of the increase in STJ supination throughout gait that would be expected if only the direct mechanical effect of the orthosis was occurring, it is noted that rapid STJ pronation occurs during late midstance. In other words, even though the inverted foot orthosis is designed to direct push the foot toward a supinated position, the foot is noted to undergo rapid pronation during the late midstance phase of gait (Fig. 1). The most reasonable explanation for this paradoxical foot pronation that I have observed in patients walking on over-inverted orthoses on many occasions is that when the CNS determines, from its afferent input, that an inversion ankle sprain may likely result from the over-inverted foot position, the CNS will then increase the efferent output to the peroneal muscles so that, during late midstance, increased STJ pronation will occur. It is very likely that these neuromotor effects of foot orthoses play a significant role in how foot orthoses may or may not be able to exert their direct mechanical effects to change the position and motion patterns of the foot and lower extremity during weightbearing activities.
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mike weber · Jun 9, 2010

Thanks Kevin,

In the example above when considering the Peroneals working to overcome the ORF of your device. If removed the CNS would adjust very quickly, the same as we have discussed in leg stiffness. When running over changed surface stiffness after the 1st contact with the surface and by the 2nd contact ( same side ) the CNS will have made adjustments to the leg stiffness required all things being equal according to research.

From individual to individual there will be differences, but is there anyway appart from pain stimulation that we could use the CNS stimulation to our advantage ?

Again, Appart from changing the foot-surface interface stiffness, (which we still don´t know how, when and why´s yet) for an individual ie what the person idea leg stiffness for the activity they are undertaking.

I maybe going around and around in circles here and coming back to what drives what, but when considering Nigg preferred motion pathways, leg stiffness it´s really got me thinking.

please note I´m not thinking about pushing on a place on the foot and calling it Proprioception, I´m more thinking about enhanced mechancial effects our device will have. I guess this more has to do with proximal changes from an orthotic rather than direct foot joint mechanical changes ie Peroneal contraction rather than direct STJ supination from Kevin´s post. or to put it another way muscle control of Joint ie internal moments rather than external moments from a device.

Peter W.B.Oomens · Nov 3, 2011

The 'propriocepsis' discussion is in my opinion just a part of the discussion of neuromodular treatment through the plantar foot. Fact is that contraction of the intrinsic footmuscles is active when a foot is loaded. These muscles, all in the length of the foot, give a 'force closure' (the opposite of form closure)of the foot bones, supported by the plantar ligaments, which we find only with human.
In my opinion is the contraction of these intrinsic muscles influenced by plantar facilitation of the footsole (baroreceptors), spine and alfa motor fibres. The gamma system (propriocepsis) is then a preset system, which constantly and rapidly adepts. In fact we have to talk about an alfa/gamma co-activation. So when we talk about these kind of insoles, we talk about exteroceptive insoles
To read more about it and find some literature, please visit my website http://www.drbody.nl

Brian A. Rothbart · Nov 3, 2011

For the past 40 years I have been engaged in research, looking at the foot mechanics and how it impacts posture. The past 10 years I have published on much of my findings.

I use the term pattens of proprioceptive stimulation to define the interaction between how the foot moves and the pattern of mechanical receptor stimulation that is a result of that particular foot motion. You may wish to give it another name. Be that as it may, I decided to use the term patterns of stimulation (the pattern of mechanical receptors being stimulated as the result of a specific foot motion).

I have found that how the foot moves has a direct impact on the posture of the body, foot to jaw (see my two fairly recent publications in the JAPMA). That is, what I refer to as linear foot motion, where hip drive directs the motion in the STJ, I have found that the resulting posture is anatomical or nearly anatomically correct (ear over the lateral malleolus). However, when the foot escapes hip drive and enters gravity drive, I find several patterns of postural distortions (the most common being the kyphotic posture).

What becomes even more interesting is the chronic pain patterns that develop from these postural distortions.

Up until 2002, the questions that remained in my mind were (1)what caused the foot to escape hip drive and enter gravity drive and (2) how did distorted patterns of stimulation (resulting from gravity drive) lead to postural distortions.

Over the past 10 years, I have proposed the following explanations to these questions:

(1) In 2002 I published a paper describing two previously unrecognized embryological foot structures, the Primus Metatarsus Supinatus and the PreClinical Clubfoot Deformity. I suggested a model on how these two abnormal foot structures takes foot mechanics out of hip drive and into gravity drive.

(2) Recently, I published a paper in Podiatry Review on a Neurophysiological Model that provides an explanation on how foot twist (hyperpronation resulting from gravity drive) could lead to postural distortions foot to jaw.

I believe my research offers a starting point in the understanding on how foot pathomechanics results in postural distortions that will lead the patient into chronic musculoskeletal pain (foot to jaw)

Brian

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