Coupling between single muscle spindle afferent and EMG in human wrist extensor muscles: physiological evidence of skeletofusimotor (beta) innervation

Kakuda, Naoyuki; Miwa, Takako; Nagaoka, Masanori

doi:10.1016/s0924-980x(98)00030-7

Cited by 22 publications

(10 citation statements)

References 15 publications

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“…Such a coupling led the fusimotor system to be considered as a simple system that prevents muscle spindle silencing during muscle shortenings (for a review, see Prochazka 1996;Vallbo et al 1979). Yet this role is already devoted to the ␤-skeletofusimotor system (Gandevia et al 1986;Kakuda et al 1998;Rothwell et al 1990). To claim that the fusimotor system presents a functional interest by itself, it is necessary to demonstrate that the CNS is able to control muscle spindle sensitivity both specifically, that is, independently of any alpha activity, and differentially, that is, in terms of static and/or dynamic sensitivity.…”

Section: Discussionmentioning

confidence: 99%

Fusimotor Drive May Adjust Muscle Spindle Feedback to Task Requirements in Humans

Ribot-Ciscar¹,

Hospod²,

Roll³

et al. 2009

Journal of Neurophysiology

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Ribot-Ciscar E, Hospod V, Roll JP, Aimonetti JM. Fusimotor drive may adjust muscle spindle feedback to task requirements in humans. J Neurophysiol 101: 633-640, 2009. First published November 26, 2008 doi:10.1152/jn.91041.2008. The aim of the present study was to investigate whether the fusimotor control of muscle spindle sensitivity may depend on the movement parameter the task is focused on, either the velocity or the final position reached. The unitary activities of 18 muscle spindle afferents were recorded by microneurography at the common peroneal nerve. We compared in two situations the responses of muscle spindle afferents to ankle movements imposed while the subject was instructed not to pay attention to or to pay attention to the movement, both in the absence of visual cues. In the two situations, three ramp-and-hold movements were imposed in random order. In one situation, the three movements differed by their velocity and in the other by the final position reached. The task consisted in ranking the three movements according to the parameter under consideration (for example, slow, fast, and medium). The results showed that paying attention to movement velocity gave rise to a significant increase in the dynamic and static responses of muscle afferents. In contrast, focusing attention on the final position reached made the muscle spindle feedback better discriminate the different positions and depressed its capacity to discriminate movement velocities. Changes are interpreted as reflecting dynamic and static gamma activation, respectively. The present results support the view that the fusimotor drive depends on the parameter the task is focused on, so that the muscle afferent feedback is adjusted to the task requirements.

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Section: Discussionmentioning

confidence: 99%

Fusimotor Drive May Adjust Muscle Spindle Feedback to Task Requirements in Humans

Ribot-Ciscar¹,

Hospod²,

Roll³

et al. 2009

Journal of Neurophysiology

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“…The association between fusimotor and skeletomotor activity could be partly attributed to skeletofusimotor (beta) action (Prochazka, 1996). Recent studies have suggested that beta‐innervation is common in forearm muscles in cats (Scott et al 1995) and in humans (Kakuda et al 1998).…”

Section: Discussionmentioning

confidence: 99%

Dynamic response of human muscle spindle afferents to stretch during voluntary contraction

Kakuda

Nagaoka

1998

The Journal of Physiology

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1. The response of twenty-eight human muscle spindle afferents from m. extensor carpi radialis brevis to large amplitude ramp stretch and release at the wrist joint was recorded. The dynamic index was calculated as the difference in firing rate between that just before the end of stretch and that during the subsequent static phase of stretch. The value during steady voluntary contraction was compared with that during relaxation. 2. In twenty-three primary afferents, the dynamic index increased in eleven and decreased in twelve afferents with a range of −8 to +25 impulses s¢. In five secondary afferents the change was less than 2 impulses s¢. 3. The primary afferents abruptly stopped firing when the stretch was released in the relaxed muscle. This cessation was prevented during contraction in seventeen primary afferents. 4. The results suggest the presence of dynamic and static fusimotor actions on the human muscle spindles during voluntary contraction.

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“…In humans, stimulation of muscular and cutaneous large diameter afferents produces short-latency excitatory and/or inhibitory responses of MNs (Buller et al, 1980 ; Garnett and Stephens, 1980 ; Chalmers and Bawa, 1997 ; Marchand-Pauvert et al, 2000 ). In monkeys and humans, the effectiveness of the coupling between MNs and peripheral afferents is demonstrated by the consistent post-spike changes in EMG activity obtained through spike-triggered averaging (Flament et al, 1992 ; Kakuda et al, 1998 ; McNulty et al, 1999 ; McNulty and Macefield, 2001 ; Fallon et al, 2005 ; Baker et al, 2006 ).…”

Section: Introductionmentioning

confidence: 90%

Motor unit firing pattern, synchrony and coherence in a deafferented patient

Schmied

Forget

Vedel

2014

Front. Hum. Neurosci.

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The firing of spinal motoneurons (MNs) is controlled continuously by inputs from muscle, joint and skin receptors. Besides altering MN synaptic drive, the removal of these inputs is liable to alter the synaptic noise and, thus, the variability of their tonic activity. Sensory afferents, which are a major source of common and/or synchronized inputs shared by several MNs, may also contribute to the coupling in the time and frequency domains (synchrony and coherence, respectively) observed when cross-correlation and coherence analyses are applied to the discharges of MN pairs. Surprisingly, no consistent changes in firing frequency, nor in synchrony and coherence were reported to affect the activity of 3 pairs of motor units (MUs) tested in a case of sensory polyradiculoneuropathy (SPRNP), leading to an irreversible loss of large diameter sensory afferents (Farmer et al., 1993). Such a limited sample, however, precludes a definite conclusion about the actual impact that a chronic loss of muscle and cutaneous afferents may have on the firing properties of human MUs. To address this issue, the firing pattern of 92 MU pairs was analyzed at low contraction force in a case of SPRNP leading similarly to a permanent loss of proprioceptive inputs. Compared with 8 control subjects, MNs in this patient tended to discharge with slightly shorter inter-spike intervals but with greater variability. Synchronous firing tended to occur more frequently with a tighter coupling in the patient. There was no consistent change in coherence in the 15–30 Hz frequency range attributed to the MN corticospinal drive, but a greater coherence was observed below 5 Hz and between 30 and 60 Hz in the patient. The possible origins of the greater irregularity in MN tonic discharges, the tighter coupling of the synchronous firing and the changes in coherence observed in the absence of proprioceptive inputs are discussed.

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Coupling between single muscle spindle afferent and EMG in human wrist extensor muscles: physiological evidence of skeletofusimotor (beta) innervation

Cited by 22 publications

References 15 publications

Fusimotor Drive May Adjust Muscle Spindle Feedback to Task Requirements in Humans

Fusimotor Drive May Adjust Muscle Spindle Feedback to Task Requirements in Humans

Dynamic response of human muscle spindle afferents to stretch during voluntary contraction

Motor unit firing pattern, synchrony and coherence in a deafferented patient

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