Amplitude et variabilité des réflexes monosynaptiques avant un mouvement volontaire

Pierrot-Deseilligny, E; Lacert, P; Cathala, H.P.

doi:10.1016/0031-9384(71)90100-4

Cited by 61 publications

(21 citation statements)

References 19 publications

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“…In this experiment performed on one subject who had at rest a large H' test reflex (4-2 mV, 24 % of Mmax), the different stimulations were randomly alternated. As previously described (Pierrot-Deseilligny et al 1971), the soleus H reflex (reference H, filled triangles) was inhibited (passing from 22 to 13 % of Mmax) before a pretibial flexor ramp contraction, but the H' test reflex (filled circles) was much more inhibited (passing from 24 to 4 % of Mmax), this difference being statistically significant (P < 001). Here also there was variation between the subjects' amount of reflex inhibition, but, in all eight subjects studied in this way, the H' test reflex was more inhibited than reference H, this difference being significant (P < 0 05) in all cases.…”

Section: Resultsmentioning

confidence: 54%

“…Before eliminating these factors which could have modified the H' test and reference H reflexes differently, a more general cause of bias has to be considered. It is easy to alter an H reflex intentionally, when the different kinds of stimulation are regularly alternated, as in the experiment (Hoffmann, 1918) or before (Pierrot-Deseilligny, Lacert & Cathala, 1971) voluntary contraction of the pretibial flexors is well-known. This inhibition is probably due in part to the activation of reciprocal Ia inhibition (Tanaka, 1974), although presynaptic inhibition of soleus Ia fibres by the Ia discharge from pretibial flexors has also been postulated to contribute to it (Gottlieb, Agarwal & Stark, 1970;Pierrot-Deseilligny & Lacert, 1973).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Facilitation of soleus‐coupled Renshaw cells during voluntary contraction of pretibial flexor muscles in man.

Katz¹,

Pierrot-Deseilligny²

1984

The Journal of Physiology

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SUMMARY1. Recurrent inhibition to soleus motoneurones, brought about by a conditioning H-reflex discharge, was estimated in human subjects by a subsequent test H reflex. Changes in recurrent inhibition during voluntary ankle dorsiflexion were evaluated by comparing the amplitude of the test H reflex to a reference H reflex: both reflexes were subjected to the same type of influences which modified soleus monosynaptic reflex excitability during pretibial flexor contraction, but only the test H reflex was subject to the recurrent inhibition evoked by the conditioning H-reflex discharge.2. During tonic or phasic ramp contractions of the pretibial flexors the inhibition of the test H reflex, as compared to rest, was more marked than that of the reference H reflex. Evidence is presented that this may indicate a facilitation of soleus-coupled Renshaw cells. Since this facilitation of soleus-coupled Renshaw cells was also observed before ramp contraction, it is, at least in part, supraspinal in origin.3. Within the range of forces studied (8-45 % of maximum force) there was no evidence that the facilitation of soleus-coupled Renshaw cells increased along with increased force of the pretibial flexor voluntary contraction. During voluntary phasic ankle dorsiflexion, facilitation of soleus-coupled Renshaw cells was maximum at the moment when soleus motoneurones were most facilitated by the stretch-induced soleus Ia discharge. There was no evidence for changes in Renshaw cell excitability during ballistic contractions.4. It is suggested that this facilitation of soleus-coupled Renshaw cells may be one of the mechanisms preventing the occurrence of a soleus stretch reflex during a voluntary ankle dorsiflexion. Such a mechanism could become important if reciprocal inhibition, via Ia inhibitory interneurones, were not strong enough, e.g. because of a weak y-drive to the contracting muscles.

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Section: Resultsmentioning

confidence: 54%

Section: Resultsmentioning

confidence: 99%

Facilitation of soleus‐coupled Renshaw cells during voluntary contraction of pretibial flexor muscles in man.

Katz¹,

Pierrot-Deseilligny²

1984

The Journal of Physiology

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“…Whatever the supraspinal structures and spinal mechanisms causing the facilitation of monosynaptic reflexes, it seems highly likely that this facilitation is just one of a number of peripheral events which precede the agonist EMG activity, since the facilitation of agonist monosynaptic re flexes is closely followed by inhibition of antagonist motoneuron activity [11]. It is suggested that these events may represent the components of a 'priming' mechanism, similar to the process postulated by Lashley [7], which is responsible for presetting (that is, facilitating or inhibiting) the constituent muscles of a movement response prior to and for the duration of the response.…”

Section: Discussionmentioning

confidence: 99%

“…Facilitation of monosynaptic stretch reflexes has been demonstrated in the muscle concerned just prior to the onset of the overt motor response in a simple reaction time task [2,9,11]. This paper deals with possible functions of this facilitation in normal man and its relationship to central processing in a choice reaction time task.…”

Section: Introductionmentioning

confidence: 99%

Lateral Facilitation of Hoffmann-Reflexes Prior to Voluntary Movement in a Choice Reaction Time Task

Michie¹,

Clarke²,

Sinden³

et al. 1975

Stereotact Funct Neurosurg

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Hoffmann reflexes (H reflexes) were elicited from both legs simultaneously in human subjects at varying intervals after a reaction signal (RS) in a binary choice reaction time task. A left light RS required a rapid plantar flexion of the left foot and a right light RS required a similar rapid response of the right foot. A large facilitation of reflex amplitude occurred only in the muscle involved in the movement (right or left soleus). The timing of the facilitation indicated that a decision about the status of the RS occurred within 200 msec and probably was completed somewhat earlier. Furthermore, the facilitation of the H reflexes was shown to be closely linked with the organization required for the contraction of the responding muscle. The results are considered in the light of hypothesized mechanisms regulating voluntary movement.

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“…To study this function in intact animals and in humans with both normal and pathological states, we still have to rely on general reflex tests of whole motor pools with mechanical stimuli (Requin 1969;Gottlieb et al 1970;Coquery and Coulmance 1971;Pierrot-Deseilligny et al 1971;Papakostopoulus and Cooper 1973;Gerilowsky et al 1983). Often the results of both mechanical and electrical reflex studies are interpreted qualitatively without much attempt to validate them against the prediction of a model of the neural network.…”

Section: Introductionmentioning

confidence: 98%

Simulations of the alpha motoneuron pool electromyogram reflex at different preactivation levels in man

Slot

Sinkjær

1994

Biol. Cybern.

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The alpha motoneuron pool and the surface electromyogram (EMG) of the human soleus muscle are modelled, respectively, by an alpha motoneuron pool model generating the firing patterns in the motor units of the muscle and by a muscle model using these discharge patterns to simulate the surface EMG. In the alpha motoneuron pool model, we use a population of motoneurons in which cellular properties like cell size and membrane conductance are distributed according to experimentally observed data. By calculating the contribution from each motor unit, the muscle model predicts the EMG. Wave forms of the motor unit action potentials in the surface EMG are obtained from experimental data. Using the model, we are able to give a quantitative prediction of the motoneuron pool activity and the reflex EMG output at different preactivation levels. The simulated data are consistent with experimentally obtained results in healthy humans. During static isometric muscle preactivations, the simulations show that the reflex strength is highly dependent on the intrinsic threshold properties of the alpha motoneuron pool.

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Amplitude et variabilité des réflexes monosynaptiques avant un mouvement volontaire

Cited by 61 publications

References 19 publications

Facilitation of soleus‐coupled Renshaw cells during voluntary contraction of pretibial flexor muscles in man.

Facilitation of soleus‐coupled Renshaw cells during voluntary contraction of pretibial flexor muscles in man.

Lateral Facilitation of Hoffmann-Reflexes Prior to Voluntary Movement in a Choice Reaction Time Task

Simulations of the alpha motoneuron pool electromyogram reflex at different preactivation levels in man

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