Scaling of Motor Output, From Mouse to Humans

Manuel, Marin; Chardon, Matthieu K.; Tysseling, Vicki M.; Heckman, C. J.

doi:10.1152/physiol.00021.2018

Cited by 39 publications

(46 citation statements)

References 76 publications

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“…However, the 𝑞 𝑆 𝐸 = 2.4-fold range obtained for cats is consistent with the fold-ranges obtained from rat and mouse data for 𝐷 𝑠𝑜𝑚𝑎 as reported in Table 4, while it underestimates the 4.4-fold range in 𝑆 𝑛𝑒𝑢𝑟𝑜𝑛 values observed in mice. Table 4 finally shows that typical cat MN sizes are larger than in rats and mice respectively, as reviewed by Manuel et al (2019). (Kernell, 1966;Cullheim, 1978;Zwaagstra, B.…”

Section: Scaling Of the Normalized Relationshipsmentioning

confidence: 86%

Mathematical Relationships between Spinal Motoneuron Properties

Caillet

Phillips

Farina

et al. 2021

Preprint

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Our understanding of the behaviour of motoneurons (MNs) in mammals partly relies on our knowledge of the relationships between MN membrane properties, such as MN size, resistance, rheobase, capacitance, time constant, axonal conduction velocity and afterhyperpolarization period. Based on scattered but converging evidence, current experimental studies and review papers qualitatively assumed that some of these MN properties are related. Here, we reprocessed the data from 27 experimental studies in cat and rat MN preparations to empirically demonstrate that all experimentally measured MN properties are associated to MN size. Moreover, we expanded this finding by deriving mathematical relationships between each pair of MN properties. These relationships were validated against independent experimental results not used to derive them. The obtained relationships support the classic description of a MN as a membrane equivalent electrical circuit and describe for the first time the association between MN size and MN membrane capacitance and time constant. The obtained relations indicate that motor units are recruited in order of increasing MN size, muscle unit size, MN rheobase, unit force recruitment thresholds and tetanic forces, but underlines that MN size and recruitment order may not be related to motor unit type.

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Section: Scaling Of the Normalized Relationshipsmentioning

confidence: 86%

Mathematical Relationships between Spinal Motoneuron Properties

Caillet

Phillips

Farina

et al. 2021

Preprint

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“…the firing patterns of single units in nXIIts, during singing are unknown (Williams and Nottebohm, 1985;Otchy et al, 2019). However, in many motor systems the electrical intrinsic properties of motor neurons and the biomechanical properties of the innervated muscle fibers are highly tuned (Zhurov and Brezina, 2006;Manuel et al, 2019). For example, the discharge rates of motor neurons typically fall within the range frequencies required to generate summed force responses by the muscle fibers.…”

Section: Discussionmentioning

confidence: 99%

Increasing Muscle Speed Drives Changes in the Neuromuscular Transform of Motor Commands during Postnatal Development in Songbirds

Adam

Elemans

2020

J. Neurosci.

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“…However, despite the increasing evidence of intensity-dependent PIC amplification, it is still not known whether this phenomenon exists in human motor neurones. Although the extrapolation of gain-control physiology from animal preparations or computational simulations to human physiology are comprehensible, it has been shown that PIC amplification varies between animals and within muscle groups 9,15,[19][20][21][22] , so direct testing across human muscles is needed 23,24 . In fact, two recent studies 23,24 reported no differences in the PIC amplitudes (estimated through paired-motor unit ΔF analysis) across different motor outputs (10%, 20%, and 30% of maximal voluntary force).…”

mentioning

confidence: 99%

Persistent Inward Currents Increase With The Level Of Voluntary Drive In Plantar Flexor Low-Threshold Motor Units

Orssatto

Mackay

Shield

et al. 2020

Preprint

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This study tested the hypothesis that estimates of persistent inward currents (PICs) in the human plantar flexors would increase with the level of voluntary drive. Twenty-one participants volunteered for this study (29.2±2.6 years). High-density surface electromyograms were collected from soleus and gastrocnemius medialis during ramp-shaped isometric contractions to 10%, 20%, and 30% (torque rise of 2%/s and 30-s duration) of each participant’s maximal torque. Motor units identified in all the contraction intensities were included in the paired-motor unit analysis to calculate delta frequency (ΔF) and estimate the PICs. Increases in PICs were observed from 10% to 20% (Δ=0.6 pps; p<0.001) and 20% to 30% (Δ=0.5 pps; p<0.001) in soleus, and from 10% to 20% (Δ=1.2 pps; p<0.001) but not 20% to 30% (Δ=0.09 pps; p=0.724) in gastrocnemius medialis. Maximal discharge rate increased for soleus and gastrocnemius medialis from 10% to 20% (respectively, Δ=1.75 pps, p<0.001; and Δ=2.43 pps, p<0.001) and 20% to 30% (respectively, Δ=0.80 pps, p<0.017; and Δ=0.92 pps, p=002). The repeated-measures correlation identified associations between ΔF and increases in maximal discharge rate for both soleus (r=0.64; p<0.001) and gastrocnemius medialis (r=0.77; p<0.001). An increase in voluntary drive tends to increase PIC strength, which has key implications for the control of force but also for comparisons between muscles or between studies when relative force levels might be different. These data indicate that increases in voluntary descending drive amplify PICs in humans and provide an important spinal mechanism for motor unit firing, and thus force output modulation.

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Scaling of Motor Output, From Mouse to Humans

Cited by 39 publications

References 76 publications

Mathematical Relationships between Spinal Motoneuron Properties

Mathematical Relationships between Spinal Motoneuron Properties

Increasing Muscle Speed Drives Changes in the Neuromuscular Transform of Motor Commands during Postnatal Development in Songbirds

Persistent Inward Currents Increase With The Level Of Voluntary Drive In Plantar Flexor Low-Threshold Motor Units

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