Contrasts between the reflex responses of tibialis anterior and triceps surae to sudden ankle rotation in normal human subjects

doi:10.1016/0013-4694(82)90179-1

Electroencephalography and Clinical Neurophysiology

Volume 54, Issue 3, September 1982, Pages 301-310

https://doi.org/10.1016/0013-4694(82)90179-1 Get rights and content

Abstract

A detailed comparative study was made of the reflex responses of human ankle flexors (tibialis anterior, TA) and extensors (triceps surae, TS) to sudden ankle rotation. Subjects were instructed to maintain a tonic contraction of either TS or TA and subjected to sudden displacements of the ankle from its midposition in either the dorsiflexing or plantarflexing directions. Joint position, torque and smoothed rectified EMGs were recorded.

The results revealed 5 principal differences in the behavior of the two muscles.

1.
(1) The TS response was typically a short, synchronous burst of activity starting at about 40 msec and lasting no more than 50 msec, termed the MSR. In contrast, the TA responses started at about the same latency but lasted much longer and frequently a second component (termed the PSR) could be distinguished.
2.
(2) The threshold of the TA reflex was much higher than that of TS.
3.
(3) Increasing displacement velocity increased the magnitude of the TS MSR as well as that of the TA MSR, but decreased the magnitude of the TA PSR.
4.
(4) Increasing the level of tonic activity augmented the magnitude of the TS activity initially but saturation soon occurred. In contrast, both components of the TA response increased with increasing tonic TA activity.
5.
(5) Finally, shortening of the tonically active TS evoked no consistent response, whereas shortening of TA evoked a significant pause in its activity.

The contrasting behavior of the ankle flexors and extensors suggest that there are significant differences in their reflex organizations.

Résumé

On a effectué chez l'homme une étude comparée détaillée des réponses réflexes des fléchisseurs (tibial antérieur, TA) et des extenseurs (triceps sural, TS), de la cheville à sa brusque rotation. Les sujets avaient pour consigne de maintenir une contraction tonique du TS ou du TA et subissaient de brusques déplacements de la cheville à partir de sa position moyenne soit en dorsiflexion soit en flexion plantaire. La position de l'articulation, le couple de torsion et l'EMG redressé et lissé étaient enregistrés.

Les résultats ont fait ressortir 5 principales différences dans le comportement des deux muscles.

1.
(1) La réponse du TS était typiquement une courte bouffée synchrone débutant environ 40 msec après le stimulus ne durant pas plus de 50 msec et dite MSA. Par opposition les réponses du TA avaient à peu près la même latence mais duraient beaucoup plus longtemps et une deuxième composante (dite PSR) pouvait fréquemment être distinguée.
2.
(2) Le seuil du réflexe du TA était beaucoup plus élevé que celui du TS.
3.
(3) En augmentant la vitesse du déplacement, on accroissait tout à la fois l'amplitude de la MSR du TS et du TA mais on diminuait celle de la PSR du TA.
4.
(4) L'intensification du niveau d'activité tonique augmentait tout d'abord l'amplitude de l'activité du TS mais une saturation se développait rapidement. En revanche, les deux composantes de la réponse du TA augmentaient avec l'intensification de l'activité tonique du TA.
5.
(5) Enfin, le racourcissement du TS toniquement actif, n'entraînait aucune réponse alors que le racourcissement du TA entraînait une nette pause d'activité.

Ce comportement différent des fléchisseurs et des extenseurs de la cheville suggère l'existence de différences significatives dans leur organisation réflexe.

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^☆: This work was supported by a grant from the Canadian Medical Research Council.

¹: Present address: School of Physical and Occupational Therapy, McGill University, Montreal, Que., Canada.

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Contrasts between the reflex responses of tibialis anterior and triceps surae to sudden ankle rotation in normal human subjectsDifférences entre les réponses réflexes du tibial antérieur et du triceps sural à une rotation soudaine de la cheville chez l'homme☆

Abstract

Résumé

Electroenceph. clin. Neurophysiol.

Brain Res.

Electroenceph. clin. Neurophysiol.

Brain Res.

Brain Res.

Responses to load disturbances in human shoulder muscles: the hypothesis that one component is a pulse test information signal

Exp. Brain Res.

Silent period produced by unloading of muscle during voluntary contractions

J. Physiol. (Lond.)

Muscle spindle responses in man to changes in load during accurate position maintenance

J. Physiol. (Lond.)

Comparison of electromyographic responses to joint displacements in human ankle flexors and extensors

Neurosci. Abstr.

Long-loop reflexes in the tranquilized monkey

Exp. Brain Res.

Evidence that the human jaw stretch reflex increases the resistance of the mandible to small displacements

J. Physiol. (Lond.)

Regulatory actions of the human stretch reflex

J. Neurophysiol.

The effects of stimulation of the static and dynamic fusimotor fibre on the response of the primary endings of muscle spindles

J. Physiol. (Lond.)

Intended arm movements in responses to externally produced arm displacements in man

Electrophysiological appraisal of relative segmental motoneuronal pool excitability in flexor and extensor muscles

J. Neurol. Neurosurg. Psychiat.

Spinal mechanisms of the functional stretch reflex

Exp. Brain Res.

Response to sudden torques about the ankle: myotatic reflex

J. Neurophysiol.