scholarly journals Shear strain rate from phase contrast velocity encoded MRI: Application to study effects of aging in the medial gastrocnemius muscle

2018 ◽  
Vol 48 (5) ◽  
pp. 1351-1357 ◽  
Author(s):  
Usha Sinha ◽  
Vadim Malis ◽  
Robert Csapo ◽  
Marco Narici ◽  
Shantanu Sinha
Keyword(s):  
Strain Rate ◽  
Shear Strain ◽  
Phase Contrast ◽  
Gastrocnemius Muscle ◽  
Medial Gastrocnemius ◽  
Shear Strain Rate ◽  
Effects Of Aging ◽  
Medial Gastrocnemius Muscle

scholarly journals 3D Muscle Deformation Mapping at Submaximal Isometric Contractions: Applications to Aging Muscle

2020 ◽  
Vol 11 ◽  
Author(s):  
Vadim Malis ◽  
Usha Sinha ◽  
Shantanu Sinha
Keyword(s):  
Extracellular Matrix ◽  
Strain Rate ◽  
Shear Strain ◽  
Compressive Strain ◽  
Strain Tensor ◽  
Medial Gastrocnemius ◽  
Strain Rate Tensor ◽  
Shear Strain Rate ◽  
Velocity Mapping ◽  
Lateral Transmission

3D strain or strain rate tensor mapping comprehensively captures regional muscle deformation. While compressive strain along the muscle fiber is a potential measure of the force generated, radial strains in the fiber cross-section may provide information on the material properties of the extracellular matrix. Additionally, shear strain may potentially inform on the shearing of the extracellular matrix; the latter has been hypothesized as the mechanism of lateral transmission of force. Here, we implement a novel fast MR method for velocity mapping to acquire multi-slice images at different % maximum voluntary contraction (MVC) for 3D strain mapping to explore deformation in the plantar-flexors under isometric contraction in a cohort of young and senior subjects. 3D strain rate and strain tensors were computed and eigenvalues and two invariants (maximum shear and volumetric strain) were extracted. Strain and strain rate indices (contractile and in-plane strain/strain rate, shear strain/strain rate) changed significantly with %MVC (30 and 60% MVC) and contractile and shear strain with age in the medial gastrocnemius. In the soleus, significant differences with age in contractile and shear strain were seen. Univariate regression revealed weak but significant correlation of in-plane and shear strain and shear strain rate indices to %MVC and correlation of contractile and shear strain indices to force. The ability to map strain tensor components provides unique insights into muscle physiology: with contractile strain providing an index of the force generated by the muscle fibers while the shear strain could potentially be a marker of lateral transmission of force.

The effect of long-term immobilization on the motor unit population of the cat medial gastrocnemius muscle

Neuroscience ◽  
1981 ◽  
Vol 6 (4) ◽  
pp. 725-739 ◽  
Author(s):  
R.F. Mayer ◽  
R.E. Burke ◽  
J. Toop ◽  
J.A. Hodgson ◽  
K. Kanda ◽  
...  
Keyword(s):  
Motor Unit ◽  
Gastrocnemius Muscle ◽  
Medial Gastrocnemius ◽  
Medial Gastrocnemius Muscle

Voluntary control of forward leaning posture relates to low-frequency neural inputs to the medial gastrocnemius muscle

2019 ◽  
Vol 68 ◽  
pp. 187-192 ◽  
Author(s):  
Tatsunori Watanabe ◽  
Ippei Nojima ◽  
Hideshi Sugiura ◽  
Basma Yacoubi ◽  
Evangelos A. Christou
Keyword(s):  
Gastrocnemius Muscle ◽  
Low Frequency ◽  
Voluntary Control ◽  
Medial Gastrocnemius ◽  
Medial Gastrocnemius Muscle

Activity and motor unit size in partially denervated rat medial gastrocnemius

1994 ◽  
Vol 76 (6) ◽  
pp. 2663-2671 ◽  
Author(s):  
L. J. Einsiedel ◽  
A. R. Luff
Keyword(s):  
Motor Unit ◽  
Gastrocnemius Muscle ◽  
Motor Units ◽  
Ventral Root ◽  
Treadmill Walking ◽  
Medial Gastrocnemius ◽  
Unit Size ◽  
Partial Denervation ◽  
Motoneuron Activity ◽  
Medial Gastrocnemius Muscle

The aim of the study was to determine whether increased motoneuron activity induced by treadmill walking would alter the extent of motoneuron sprouting in the partially denervated rat medial gastrocnemius muscle. An extensive partial denervation was effected by unilateral section of the L5 ventral root, and it is very likely that all units remaining in the medial gastrocnemius were used in treadmill walking. Rats were trained for 1.5 h/day and after 14 days were walking at least 1 km/day. Motor unit characteristics were determined 24 days after the partial denervation and were compared with units from partially denervated control (PDC) animals and with units from normal (control) animals. In PDC rats, force developed by slow, fast fatigue-resistant, and fast intermediate-fatigable motor units increased substantially compared with control animals; that of fast-fatigable units did not increase. In partially denervated exercised animals, force developed by slow and fast-fatigue-resistant units showed no further increase, but fast-intermediate- and fast-fatigable units showed significant increases compared with those in PDC animals. The changes in force were closely paralleled by changes in innervation ratios. We concluded that neuronal activity is an important factor in determining the rate of motoneuron sprouting.

Fast-to-Slow Conversion Following Chronic Low-Frequency Activation of Medial Gastrocnemius Muscle in Cats. II. Motoneuron Properties

1997 ◽  
Vol 77 (5) ◽  
pp. 2605-2615 ◽  
Author(s):  
John B. Munson ◽  
Robert C. Foehring ◽  
Lorne M. Mendell ◽  
Tessa Gordon
Keyword(s):  
Gastrocnemius Muscle ◽  
Low Frequency ◽  
Motor Units ◽  
Input Resistance ◽  
Medial Gastrocnemius ◽  
Excitatory Postsynaptic Potential ◽  
Chronic Stimulation ◽  
General Hypothesis ◽  
Slow Type ◽  
Medial Gastrocnemius Muscle

Munson, John B., Robert C. Foehring, Lorne M. Mendell, and Tessa Gordon. Fast-to-slow conversion following chronic low-frequency activation of medial gastrocnemius muscle in cats. II. Motoneuron properties. J. Neurophysiol. 77: 2605–2615, 1997. Chronic stimulation (for 2–3 mo) of the medial gastrocnemius (MG) muscle nerve by indwelling electrodes renders the normally heterogeneous MG muscle mechanically and histochemically slow (type SO). We tested the hypothesis that motoneurons of MG muscle thus made type SO by chronic stimulation would also convert to slow phenotype. Properties of all single muscle units became homogeneously type SO (slowly contracting, nonfatiguing, nonsagging contraction during tetanic activation). Motoneuron electrical properties were also modified in the direction of type S, fatigue-resistant motor units. Two separate populations were identified (on the basis of afterhyperpolarization, rheobase, and input resistance) that likely correspond to motoneurons that had been fast (type F) or type S before stimulation. Type F motoneurons, although modified by chronic stimulation, were not converted to the type S phenotype, despite apparent complete conversion of their muscle units to the slow oxidative type (type SO). Muscle units of the former type F motor units were faster and/or more powerful than those of the former type S motor units, indicating some intrinsic regulation of motor unit properties. Experiments in which chronic stimulation was applied to the MG nerve cross-regenerated into skin yielded changes in motoneuron properties similar to those above, suggesting that muscle was not essential for the effects observed. Modulation of group Ia excitatory postsynaptic potential (EPSP) amplitude during high-frequency trains, which in normal MG motoneurons can be either positive or negative, was negative in 48 of 49 chronically stimulated motoneurons. Negative modulation is characteristic of EPSPs in motoneurons of most fatigue-resistant motor units. The general hypothesis of a periphery-to-motoneuron retrograde mechanism was supported, although the degree of control exerted by the periphery may vary: natural type SO muscle appears especially competent to modify motoneuron properties. We speculate that activity-dependent regulation of the neurotrophin-(NT) 4/5 in muscle plays an important role in controlling muscle and motoneuron properties.

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