Divergent projection of individual corticospinal axons to motoneurons of multiple muscles in the monkey

Shinoda, Yoshikazu; Yokota, Jun‐Ichi; Futami, Takahiro

doi:10.1016/0304-3940(81)90182-8

Cited by 496 publications

(131 citation statements)

References 8 publications

Supporting

Mentioning

125

Contrasting

Unclassified

Order By: Relevance

“…Precise comparison between muscle synergies found pre-and post-transection at different levels of the neuraxis suggested that a majority of muscle synergies underlying natural movement in frogs is expressed by the neural circuits within the brain stem and spinal cord (Roh et al 2011a). In addition, some electrophysiological and anatomical studies have suggested that neurons in the primary motor cortex (M1) are involved in expressing muscle synergies in mammals (Drew et al 2008;Futami et al 1979;Gentner and Classen 2006;Li and Martin 2002;Shinoda et al 1976Shinoda et al , 1981Shinoda et al , 1986. We reason that the two views, derived from experiments with a lower vertebrate and mammals, respectively, could be reconciled in the sense that the "old" M1 (Rathelot and Strick 2009), sending descending fibers primarily to the spinal interneurons, generates movements by flexibly activating synergies expressed downstream, whereas the "new" M1 is involved in encoding the more diverse movements peculiar to higher primates and humans (Roh et al 2011a;Yakovenko et al 2011).…”

Section: Neural Circuitries Involved In Expressing Muscle Synergiesmentioning

confidence: 99%

Robustness of muscle synergies underlying three-dimensional force generation at the hand in healthy humans

Roh

Rymer

Beer

2012

Journal of Neurophysiology

125

141

View full text Add to dashboard Cite

Roh J, Rymer WZ, Beer RF. Robustness of muscle synergies underlying three-dimensional force generation at the hand in healthy humans. J Neurophysiol 107: 2123-2142, 2012. First published January 25, 2012 doi:10.1152/jn.00173.2011.-Previous studies using advanced matrix factorization techniques have shown that the coordination of human voluntary limb movements may be accomplished using combinations of a small number of intermuscular coordination patterns, or muscle synergies. However, the potential use of muscle synergies for isometric force generation has been evaluated mostly using correlational methods. The results of such studies suggest that fixed relationships between the activations of pairs of muscles are relatively rare. There is also emerging evidence that the nervous system uses independent strategies to control movement and force generation, which suggests that one cannot conclude a priori that isometric force generation is accomplished by combining muscle synergies, as shown in movement control. In this study, we used non-negative matrix factorization to evaluate the ability of a few muscle synergies to reconstruct the activation patterns of human arm muscles underlying the generation of three-dimensional (3-D) isometric forces at the hand. Surface electromyographic (EMG) data were recorded from eight key elbow and shoulder muscles during 3-D force target-matching protocols performed across a range of load levels and hand positions. Four synergies were sufficient to explain, on average, 95% of the variance in EMG datasets. Furthermore, we found that muscle synergy composition was conserved across biomechanical task conditions, experimental protocols, and subjects. Our findings are consistent with the view that the nervous system can generate isometric forces by assembling a combination of a small number of muscle synergies, differentially weighted according to task constraints. motor control; motor primitives; human upper limb; muscle synergy

show abstract

Section: Neural Circuitries Involved In Expressing Muscle Synergiesmentioning

confidence: 99%

Robustness of muscle synergies underlying three-dimensional force generation at the hand in healthy humans

Roh

Rymer

Beer

2012

Journal of Neurophysiology

125

141

View full text Add to dashboard Cite

show abstract

“…They include the divergence of corticospinal axons to reach more than one motoneuron pool (e.g., Cheney 1978, 1980;Shinoda et al 1981; for review, see Lemon 2008) and the major overlapping and intermingling of cortical output zones to individual upper limb muscles documented in nonhuman primates (e.g., Landgren et al 1962;Rathelot and Strick 2006;Schieber and Hibbard 1993). As a result of such factors, there is short-term synchronization of motor unit discharge of functionally linked hand muscles or across muscle compartments of the multitendoned extrinsic hand muscles (Hockensmith et al 2005;Johnston et al 2005;Nordstrom et al 1992;Reilly et al 2004;Santello and Fuglevand 2004;Winges and Santello 2004).…”

Section: Mechanisms Of Force Enslavement and Force Deficitmentioning

confidence: 99%

“…Furthermore, motor cortical neurons commonly diverge to innervate the motoneuron pools of several forearm and intrinsic hand muscles (e.g., Buys et al 1986;Fetz and Cheney 1980;Schieber and Santello 2004;Shinoda et al 1979Shinoda et al , 1981.…”

mentioning

confidence: 99%

Limits to the Control of the Human Thumb and Fingers in Flexion and Extension

Duinen

Gandevia

2010

Journal of Neurophysiology

View full text Add to dashboard Cite

show abstract

“…A similar proportion of inputs could be disrupted following stroke because motor cortical territory for proximal and distal muscles is strongly overlapping (Park et al, 2001) and as the axons descend through the subcortical structures, they are densely packed together (Morecraft et al, 2007). Additionally, the output from the motor cortical areas is divergent to multiple spinal motoneuron pools (Fetz and Cheney, 1980;Shinoda et al, 1981;Schieber, 2001), some of which may control more proximal muscles and some of which may control more distal muscles. Thus, in our sample with heterogeneous lesions, damage to many locations within the motor system may result in a similar disruption to proximal and distal inputs.…”

Section: The Absence Of a Proximal To Distal Gradient In Motor Deficitsmentioning

confidence: 99%

Absence of a proximal to distal gradient of motor deficits in the upper extremity early after stroke

Beebe¹,

Lang²

2008

Clinical Neurophysiology

View full text Add to dashboard Cite

Objective-Our first purpose was to determine whether there was a proximal to distal gradient in motor deficits in nine segments of the affected upper extremity (shoulder, elbow, forearm, wrist, and 5 fingers) post stroke. Our second purpose was to determine which upper extremity segments made the greatest contributions to hand function.Methods-33 subjects were tested on average 18.6 (± 5.6) days after stroke. The ability to move each segment was measured by active range of motion (AROM). Hand function was measured by a battery of standardized clinical tests which were synthesized into a single, sensitive score for hand function using principal components analysis.Results-AROM at all nine segments of the upper extremity was reduced and there was no evidence of a proximal to distal gradient in AROM values. Strength of each segment was reduced and there was also no evidence of a gradient in strength values. AROM at each segment was strongly correlated with hand function scores (range 0.76 -0.94). General multiple regression analysis showed that AROM explained 82% of the variance in hand function, with most of the variance shared across proximal, middle, and distal segments. Hierarchical regression analysis showed that shoulder AROM alone could explain 88% of the variance in hand function.Conclusion-Early after stroke a proximal to distal gradient of motor deficits was not present, and loss of hand function was due to a loss of ability to move many segments of the upper extremity and not just the distal ones.Significance-These results suggest that a change in the clinical perception of motor deficits post stroke is needed. Our finding that shoulder AROM predicted almost all the variance in hand function opens up the possibility that this quick, simple measure may be predictive of future hand function. This would be of high economic and clinical utility compared to other ongoing efforts attempting to predict outcomes post stroke (e.g. fMRI, MEG).

show abstract

Divergent projection of individual corticospinal axons to motoneurons of multiple muscles in the monkey

Cited by 496 publications

References 8 publications

Robustness of muscle synergies underlying three-dimensional force generation at the hand in healthy humans

Robustness of muscle synergies underlying three-dimensional force generation at the hand in healthy humans

Limits to the Control of the Human Thumb and Fingers in Flexion and Extension

Absence of a proximal to distal gradient of motor deficits in the upper extremity early after stroke

Contact Info

Product

Resources

About