Functional Relations Between Primate Motor Cortex Cells and Muscles: Fixed and Flexible

Ee, Fetz; Pd, Cheney

doi:10.1002/9780470513545.ch7

Cited by 44 publications

(22 citation statements)

References 31 publications

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“…This highlights that the central drive to pairs of antagonistic muscles is organized differently from the central drive to the individual agonist muscles, as has been suggested from analysis of segmental reflex mechanisms during cocontraction (21). The reduction in motor-evoked potentials during cocontraction ob- (6). Reducing the activity of such corticomotoneuronal cells and allowing circuitries that provide a common drive to antagonist motor units to become more active is a likely mechanism behind the increased coherence between the antagonistic motor units observed here.…”

Section: Discussionmentioning

confidence: 71%

Central common drive to antagonistic ankle muscles in relation to short-term cocontraction training in nondancers and professional ballet dancers

Geertsen

Kjaer

Pedersen

et al. 2013

Journal of Applied Physiology

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Optimization of cocontraction of antagonistic muscles around the ankle joint has been shown to involve plastic changes in spinal and cortical neural circuitries. Such changes may explain the ability of elite ballet dancers to maintain a steady balance during various ballet postures. Here we investigated whether short-term cocontraction training in ballet dancers and nondancers leads to changes in the coupling between antagonistic ankle motor units. Eleven ballet dancers and 10 nondancers were recruited for the study. Prior to training, ballet dancers and nondancers showed an equal amount of coherence in the 15- to 35-Hz frequency band and short-term synchronization between antagonistic tibialis anterior and soleus motor units. The ballet dancers tended to be better at maintaining a stable cocontraction of the antagonistic muscles, but this difference was not significant (P = 0.09). Following 27 min of cocontraction training, the nondancers improved their performance significantly, whereas no significant improvement was observed for the ballet dancers. The nondancers showed a significant increase in 15- to 35-Hz coherence following the training, whereas the ballet dancers did not show a significant change. A group of control subjects (n = 4), who performed cocontraction of the antagonistic muscles for an equal amount of time, but without any requirement to improve their performance, showed no change in coherence. We suggest that improved ability to maintain a stable cocontraction around the ankle joint is accompanied by short-term plastic changes in the neural drive to the involved muscles, but that such changes are not necessary for maintained high-level performance.

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Section: Discussionmentioning

confidence: 71%

Central common drive to antagonistic ankle muscles in relation to short-term cocontraction training in nondancers and professional ballet dancers

Geertsen

Kjaer

Pedersen

et al. 2013

Journal of Applied Physiology

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“…These adjustments in segmental reflex pathways are likely caused by changes in the supraspinal control of the involved interneuronal populations. Both monkey and human experiments have suggested that different populations of corticospinal cells are responsible for the descending control during cocontraction compared with isolated flexion and extension movements (Aimonetti et al 2002;Fetz and Cheney 1987;Humphrey and Reed 1983;Johannsen et al 2000;Nielsen et al 1993b).…”

Section: Introductionmentioning

confidence: 58%

Task-Specific Depression of the Soleus H-Reflex After Cocontraction Training of Antagonistic Ankle Muscles

Perez

Lundbye‐Jensen

Nielsen

2007

Journal of Neurophysiology

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Perez MA, Lundbye-Jensen J, Nielsen JB. Task-specific depression of the soleus H-reflex after cocontraction training of antagonistic ankle muscles. J Neurophysiol 98: 3677-3687, 2007. First published October 17, 2007 doi:10.1152/jn.00988.2007. Ballet dancers have small soleus (SOL) H-reflex amplitudes, which may be related to frequent use of cocontraction of antagonistic ankle muscles. Indeed, SOL H-reflexes are depressed during cocontraction compared with plantarflexion at matched background EMG level. We investigated the effect of 30-min training of simultaneous activation of ankle dorsiand plantarflexor muscles (cocontraction task) on the SOL H-reflex in 10 healthy volunteers. Measurements were taken during cocontraction. After training, there was a significant improvement in the ability of the subjects to perform a stable cocontraction. SOL H-reflex recruitment curves and H-max/M-max ratios were decreased after cocontraction training but not after 30 min of static dorsi or plantarflexion. The decreased H-reflex size correlated with improved motor performance. No changes in SOL and tibialis anterior (TA) EMG activity or EMG power were observed, suggesting that increased presynaptic inhibition of Ia afferents is a likely mechanism for H-reflex depression. In different sessions we measured SOL and TA motor-evoked potentials (MEPs) by using transcranial magnetic stimulation (TMS), TMS-elicited suppression of SOL EMG, and coherence between electroencephalographic (EEG) activity (Cz) and TA and SOL EMG. SOL and TA MEPs were depressed, whereas TMSelicited suppression of SOL EMG and coherence were increased after training. Decreased excitability of corticospinal neurons due to increased intracortical inhibition seems a likely explanation of these observations. Our results indicate that the depression in H-reflex observed during a cocontraction task can be trained and that repeated performance of tasks involving cocontraction may lead to prolonged changes in reflex and corticospinal excitability.

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“…We now know that during such an instructed delay period neural activity related to the specific upcoming movement appears in a wide variety of cortical and subcortical structures (Prut & Fetz, 1999; Buford & Davidson, 2004), including a substantial proportion of M1 neurons (Tanji & Evarts, 1976; Thach, 1978; Alexander & Crutcher, 1990 b ). During instructed delays, neurons in M1 (including CM cells; Fetz & Cheney, 1987) and elsewhere thus may be active for hundreds of milliseconds in the absence of EMG activity or limb movement.…”

Section: Temporal Dissociation During Instructed Delaysmentioning

confidence: 99%

“…While the PSF produced by a CM cell in a given muscle's EMG generally has been regarded as relatively fixed, a more flexible relationship between the level of activity in the CM cell and the level of activity in the target muscle has been observed in a variety of situations (Fetz & Cheney, 1987). CM cells are among those M1 neurons that may begin to discharge well before their target muscles become active.…”

Section: Dissociating Cortico‐motoneuronal Cells From Their Target Mumentioning

confidence: 99%

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Dissociating motor cortex from the motor

Schieber

2011

The Journal of Physiology

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During closed-loop control of a brain-computer interface, neurons in the primary motor cortex can be intensely active even though the subject may be making no detectable movement or muscle contraction. How can neural activity in the primary motor cortex become dissociated from the movements and muscles of the native limb that it normally controls? Here we examine circumstances in which motor cortex activity is known to dissociate from movement -including mental imagery, visuo-motor dissociation and instructed delay. Many such motor cortex neurons may be related to muscle activity only indirectly. Furthermore, the integration of thousands of synaptic inputs by individual α-motoneurons means that under certain circumstances even cortico-motoneuronal cells, which make monosynaptic connections to α-motoneurons, can become dissociated from muscle activity. The natural ability of motor cortex neurons under voluntarily control to become dissociated from bodily movement may underlie the utility of this cortical area for controlling brain-computer interfaces.

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Functional Relations Between Primate Motor Cortex Cells and Muscles: Fixed and Flexible

Cited by 44 publications

References 31 publications

Central common drive to antagonistic ankle muscles in relation to short-term cocontraction training in nondancers and professional ballet dancers

Central common drive to antagonistic ankle muscles in relation to short-term cocontraction training in nondancers and professional ballet dancers

Task-Specific Depression of the Soleus H-Reflex After Cocontraction Training of Antagonistic Ankle Muscles

Dissociating motor cortex from the motor

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