On the subdivision of static and dynamic fusimotor actions on the primary ending of the cat muscle spindle.

Emonet-Dénand, F; Laporte, Y; Matthews, P. B. C.; Petit, J.

doi:10.1113/jphysiol.1977.sp011884

Cited by 204 publications

(63 citation statements)

References 25 publications

(43 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, our work suggest that, during a rapid muscle stretch, e.g., during a loss of balance, the amplification of dynamic Ia component in motoneurons will help to regain ones equilibrium. Fast PICs thus seem to have the same overall effect as the dynamic ␥-motoneurons, which augments the dynamic sensitivity of primary endings and the dynamic component of the proprioceptive feedback to motoneurons (Crowe and Matthews, 1964;Emonet-Denand et al, 1975;Emonet-Denand et al, 1977).…”

Section: Impact Of the Differential Amplification On Motoneuron Recrumentioning

confidence: 94%

“…This leads to a strong amplification of the static component. This effect is reminiscent of the action of static fusimotor axons (Emonet-Denand et al, 1977) on primary endings and might help slow motoneurons to discharge during sustained stretches. Because the S motor units are resistant to fatigue, the resulting sustained contraction might contribute to maintain posture.…”

Section: Impact Of the Differential Amplification On Motoneuron Recrumentioning

confidence: 99%

See 1 more Smart Citation

Resonant or Not, Two Amplification Modes of Proprioceptive Inputs by Persistent Inward Currents in Spinal Motoneurons

Manuel¹,

Meunier²,

Donnet³

et al. 2007

J. Neurosci.

View full text Add to dashboard Cite

Why do motoneurons possess two persistent inward currents (PICs), a fast sodium current and a slow calcium current? To answer this question, we replaced the natural PICs with dynamic clamp-imposed artificial PICs at the soma of spinal motoneurons of anesthetized cats. We investigated how PICs with different kinetics (1-100 ms) amplify proprioceptive inputs. We showed that their action depends on the presence or absence of a resonance created by the I h current. In resonant motoneurons, a fast PIC enhances the resonance and amplifies the dynamic component of Ia inputs elicited by ramp-and-hold muscle stretches. This facilitates the recruitment of these motoneurons, which likely innervate fast contracting motor units developing large forces, e.g., to restore balance or produce ballistic movements. In nonresonant motoneurons, in contrast, a fast PIC easily triggers plateau potentials, which leads to a dramatic amplification of the static component of Ia inputs. This likely facilitates the recruitment of these motoneurons, innervating mostly slowly contracting and fatigue-resistant motor units, during postural activities. Finally, a slow PIC may switch a resonant motoneuron to nonresonant by counterbalancing I h , thus changing the action of the fast PIC. A modeling study shows that I h needs to be located on the dendrites to create the resonance, and it predicts that dendritic PICs amplify synaptic input in the same manner as somatic PICs.

show abstract

Section: Impact Of the Differential Amplification On Motoneuron Recrumentioning

confidence: 94%

Section: Impact Of the Differential Amplification On Motoneuron Recrumentioning

confidence: 99%

Resonant or Not, Two Amplification Modes of Proprioceptive Inputs by Persistent Inward Currents in Spinal Motoneurons

Manuel¹,

Meunier²,

Donnet³

et al. 2007

J. Neurosci.

View full text Add to dashboard Cite

show abstract

“…Repetitive stimulation of y static axons during periods of blood occlusion may result in a high concentration of potassium in the capsule sleeve and depolarization of the bag1 fibre membrane in this region. Secondly, it now seems unlikely that all primary-ending responses in categories III-V involve the activation of the bag1 fibre in addition to bag2 and/or chain fibres as proposed by Emonet-Denand, Laporte, Matthews & Petit (1977). We suggest that the variability of the static response is largely due to the activation of bag2 and chain fibres, either on their own, or in various combinations in one or both poles of a spindle, with the additional activation of the bag1 fibre making only an occasional contribution.…”

Section: Ppproceedings Of Thementioning

confidence: 99%

Communications

1981

The Journal of Physiology

View full text Add to dashboard Cite

Neurology, Queen Square, LondonBiochemical data suggest that L-glutamate (L-glu) and L-aspartate (L-asp) could be the neurotransmitters of the parallel and the climbing fibres respectively in the mammalian cerebellum. We have now used in vitro sagittal slices of adult rat cerebellum to study the responses of Purkinje cells (PCs) to ionophoretic applications of L-glu and L-asp in the molecular layer.Extra-and intra-cellular recordings were made from eighty PCs and L-glu and L-asp were released into their dendritic fields by short current pulses (5 to 100 msec) through a separate multibarelled electrode filled with 0 5 M salt solutions of the drugs.In the nineteen cells recorded from intracellularly, transient depolarizations up to 17 mV in amplitude and with depolarizing slopes up to 0 4 mV/msec were evoked by 2 to 10 nC L-glu or L-asp applied in the molecular layer. Maximum sensitivities were 8 mV/nC for L-glu and 6-4 mV/nC for L-asp. These depolarizations were accompanied by no change in cell input resistance, whereas steady applications of high doses of L-asp or L-glu decreased the membrane resistance.In the extracellularly recorded cells, the lowest threshold for L-glu or L-asp mediated excitations of PCs was as low as 25 pC, with a latency for the response as short as 7 msec. The mapping of these excitatory responses confirmed that the sensitivity of the dendrites for L-glu was greater than that of the soma (Chujo, Yamada & Yamamoto, 1975), and we showed in addition that the same was true for L-asp. No differential sensitivity of PC dendrites for L-asp and L-glu was detected in 66 0 of the tested cells; in the remainder, the sensitivity for L-asp declined markedly in the upper third of the molecular layer, whereas it remained high for L-glu.Finally, the agonist quisqualic acid was a much more potent excitant of PCs than L-glu or L-asp when applied in their dendritic fields, whereas the other major agonist N-methyl DL-aspartate (Sigma) only produced a very weak excitatory effect under the same conditions. The excitatory effects of L-asp, L-glu and quisqualic acid on PCs were antagonized by L-glutamic acid diethyl ester more consistently than by D-a amino adipate, suggesting, together with the previous observations, that L-asp and L-glu act on PCs via quisqualic acid receptors rather than via N-methyl D-aspartate receptors.

show abstract

“…The method used for preparing functionally single y as well as single afferent fibres has already been described in detail (for instance, see Emonet-Denand, Laporte, Matthews & Petit, 1977). The actions, either dynamic or static, exerted by these axons on the discharges of primary endings in response to a 3 5 mm ramp-and-hold muscle stretch at 8 mm/s (the plateau length being at maximal length) was determined by the criteria of Crowe & Matthews (1964) and Emonet-D6nand et al (1977).…”

Section: Preparationmentioning

confidence: 99%

Primary and secondary afferent discharges from the same spindle during chain fibre contraction in cat tenuissimus muscle

Celichowski¹,

Emonet-Dénand²,

Gladden³

et al. 1994

Experimental Physiology

Self Cite

View full text Add to dashboard Cite

SUMMARYPairs of I a and II afferent fibres supplying primary and secondary endings lying in the same tenuissimus spindles were prepared in barbiturate anaesthetized cats in order to compare the variability in the rhythm of discharge of the two endings during responses elicited by the contraction of different intrafusal muscle fibres, especially by chain fibres. In these spindles, the intrafusal muscle fibres supplied by single static y-axons were identified with a recently developed technique based on the types of primary ending activation observed during y stimulation at 30 and 100 stimuli/s. The responses of the secondary endings to contraction of chain fibres either alone or with bag2 fibres were smaller and much more regular than the responses of the primary endings lying in the same spindles. This difference is probably related to the position of secondary endings along the intrafusal muscle fibres and to the mechanical properties of the muscle fibre regions on which the terminals lie. The dynamic properties of the encoding site of primary afferent impulses probably contribute to the difference. The different degrees of variability observed among secondary ending responses elicited either by chain fibres alone or by chain and bag2 fibres are not related to the type of activated intrafusal muscle fibres.

show abstract

On the subdivision of static and dynamic fusimotor actions on the primary ending of the cat muscle spindle.

Abstract: 8. Responses to large amplitude sinusoidal stretching were also studied in relation to our classification.

Cited by 204 publications

References 25 publications

Resonant or Not, Two Amplification Modes of Proprioceptive Inputs by Persistent Inward Currents in Spinal Motoneurons

Resonant or Not, Two Amplification Modes of Proprioceptive Inputs by Persistent Inward Currents in Spinal Motoneurons

Communications

Primary and secondary afferent discharges from the same spindle during chain fibre contraction in cat tenuissimus muscle

Contact Info

Product

Resources

About