Interactions between voluntary and postural mechanisms of thehuman motor system.

Gottlieb, Gerald L.; Agarwal, Gyan C.; Stark, Lawrence

doi:10.1152/jn.1970.33.3.365

Cited by 178 publications

(58 citation statements)

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“…The presence of augmented H reflexes independent of altered skeletomotor activity during imagination of movements implies that mental rehearsal can activate descending inputs to spinal reflex circuits. Changes in spinal reflexes are well documented prior to deliberate movement in the absence of EMG (Kots, 1969;Gottlieb, Agarwal & Stark, 1970;Coquery & Coulmance, 1971;PierrotDeseilligny & Lacert, 1973), and this rather than enhanced fusimotor drive probably constitutes the mental set associated with the preparation for movement. The present findings are similar to the changes that occur when subjects are provided with a warning that a stimulus to which they must respond is imminent (Burke, McKeon, Skuse & Westerman, 1980).…”

Section: Discussionmentioning

confidence: 99%

Mental rehearsal of motor tasks recruits α‐motoneurones but fails to recruit human fusimotor neurones selectively

Gandevia

Wilson

Inglis

et al. 1997

The Journal of Physiology

107

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As mental rehearsal of movements activates multiple cortical areas associated with movement, we assessed whether this increases fusimotor drive and whether enhanced muscle spindle activity could contribute to the improvement in skill that accompanies mental rehearsal. Microneurographic recordings were made from six muscle spindle afferents innervating extensor muscles in the forearm or tibialis anterior, which were selected because their discharge increased during very weak contractions. Activity was monitored while subjects imagined performing a range of activities including simple and complex movements involving the relevant muscles. No activation of muscle spindle afferents occurred during imagined motor tasks without EMG. When the relevant muscles contracted during mental rehearsal, spindle discharge increased, much as in weak contractions. Mental rehearsal increased background EMG in the involved muscles and also increased H reflex amplitude independently of EMG changes. Although there was no evidence for selective fusimotor activation during imagined movement, skeletomotor activity and reflex excitability increased. Similar changes occur with preparation for movement following a cue. It is likely that mental rehearsal usually involves unintentional performance of the planned motor task.

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Section: Discussionmentioning

confidence: 99%

Mental rehearsal of motor tasks recruits α‐motoneurones but fails to recruit human fusimotor neurones selectively

Gandevia

Wilson

Inglis

et al. 1997

The Journal of Physiology

107

View full text Add to dashboard Cite

show abstract

“…Normal reflexes are not this fast. For example, the H-reflex, which does not include a sensory organ and is, therefore, only a portion of a reflex arc, has a 30 msec latency (18).…”

Section: Discussionmentioning

confidence: 99%

Dynamic overshoot in saccadic eye movements is caused by neurological control signal reversals

Bahill

Clark

Stark

1975

Experimental Neurology

163

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“…Spinal contribution to excitability changes may be due to corticofugal influences before movement or to afferent inputs following the movement. Spinal facilitation has been demonstrated only between 50 and 100 ms before EMG onset [6,11] and thus cannot explain the excitability changes beyond this time period. The effect of afferent inputs after movement is unlikely because afferent inputs have been shown not to affect spinal motoneuron or interneuron excitability [20].…”

Section: Factors Contributing To Motor Excitabilitymentioning

confidence: 98%

Time course of motor excitability before and after a task-related movement

Zaaroor

Pratt

Starr

2003

Neurophysiologie Clinique/Clinical Neurophysiology

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Aims of the study. -The time course of motor excitability during a task-related unilateral right thumb movement was studied using sub-threshold transcranial magnetic stimulation (TMS) to the contralateral left motor cortex. The level of stimulation evoked a motor evoked potential (MEP) in the thumb when the subject was at rest in approximately 10% of the trials.Methods. -Subjects made a brief right thumb movement to the predictable omission of regularly presented tone bursts allowing experimental definition of TMS relative to the cue to move. Motor cortical excitability was characterized by amplitude and/or probability of eliciting MEPs.Results. -There were four periods of altered motor excitability during task performance compared to a control resting state: a first period of weak facilitation before movement between -500 to -200 ms, a second period without increased excitability approximately 150 ms before movement onset when MEPs amplitude was below that seen in rest, a third period of strong facilitation between -100 ms before movement and +200 ms after facilitation and a fourth period of weak facilitation between +200 to +500 ms.Conclusion. -These results show that during performance of a task requiring a motor response, motor cortical excitability is increased above resting for hundreds of millisecond before and after the response, except for a transient period between 75 and 150 ms prior to movement onset. The temporal pattern of these excitability changes is compatible with multiple excitatory and inhibitory inputs interacting on motor cortex.© 2003 Éditions scientifiques et médicales Elsevier SAS. All rights reserved. RésuméObjectif de l'étude. -Étudier le décours temporel de l'excitabilité motrice pendant une tâche de mouvement du pouce droit, en délivrant une stimulation magnétique transcranienne (TMS) à un niveau infra-liminaire sur le cortex moteur contralatéral. À ce niveau de stimulation, nous avons obtenu l'apparition d'un potentiel évoqué moteur (PEM) dans le pouce, avec les sujets au repos, dans 10 % des essais.Méthodes. -Les sujets faisaient un bref mouvement du pouce droit en réponse à l'omission (prédictible) de bruits blancs présentés régulièrement. Ceci nous a permis de définir différentes fenêtres d'application de la TMS, avant ou après le mouvement du doigt. L'excitabilité motrice corticale était alors définie par l'amplitude et/ou la probabilité de produire un PEM.Résultats. -Il est apparu 4 périodes au cours desquelles l'excitabilité motrice était altérée en comparaison à un niveau de repos : une première période de faible facilitation avant le mouvement, entre -500 et -200 ms, une seconde période sans augmentation de l'excitabilité, environ 150 ms avant le début du mouvement (l'amplitude des PEM étant inférieure à celle pendant les périodes de repos), une troisième période de forte facilitation entre -100 ms avant le mouvement et +200 ms après la facilitation, enfin une quatrième période de faible facilitation entre +200 et +500 ms.Conclusion. -Ces résultats montrent que, pend...

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Interactions between voluntary and postural mechanisms of thehuman motor system.

Cited by 178 publications

References 0 publications

Mental rehearsal of motor tasks recruits α‐motoneurones but fails to recruit human fusimotor neurones selectively

Mental rehearsal of motor tasks recruits α‐motoneurones but fails to recruit human fusimotor neurones selectively

Dynamic overshoot in saccadic eye movements is caused by neurological control signal reversals

Time course of motor excitability before and after a task-related movement

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