scholarly journals Corticospinal-evoked responses in lower limb muscles during voluntary contractions at varying strengths

2008 ◽  
Vol 105 (5) ◽  
pp. 1527-1532 ◽  
Author(s):  
T. Oya ◽  
B. W. Hoffman ◽  
A. G. Cresswell
Keyword(s):  
Evoked Potentials ◽  
Upper Limb ◽  
Lower Limb ◽  
Motor Evoked Potentials ◽  
Voluntary Contraction ◽  
Medial Gastrocnemius ◽  
Evoked Responses ◽  
Lower Limb Muscles ◽  
Limb Muscles ◽  
Voluntary Contractions

This study investigated corticospinal-evoked responses in lower limb muscles during voluntary contractions at varying strengths. Similar investigations have been made on upper limb muscles, where evoked responses have been shown to increase up to ∼50% of maximal force and then decline. We elicited motor-evoked potentials (MEPs) and cervicomedullary motor-evoked potentials (CMEPs) in the soleus (Sol) and medial gastrocnemius (MG) muscles using magnetic stimulation over the motor cortex and cervicomedullary junction during voluntary plantar flexions with the torque ranging from 0 to 100% of a maximal voluntary contraction. Differences between the MEP and CMEP were also investigated to assess whether any changes were occurring at the cortical or spinal levels. In both Sol and MG, MEP and CMEP amplitudes [normalized to maximal M wave (Mmax)] showed an increase, followed by a plateau, over the greater part of the contraction range with responses increasing from ∼0.2 to ∼6% of Mmax for Sol and from ∼0.3 to ∼10% of Mmax for MG. Because both MEPs and CMEPs changed in a similar manner, the observed increase and lack of decrease at high force levels are likely related to underlying changes occurring at the spinal level. The evoked responses in the Sol and MG increase over a greater range of contraction strengths than for upper limb muscles, probably due to differences in the pattern of motor unit recruitment and rate coding for these muscles and the strength of the corticospinal input.

scholarly journals Inter-muscle differences in modulation of motor evoked potentials and posterior root-muscle reflexes evoked from lower-limb muscles during agonist and antagonist muscle contractions

2020 ◽  
Author(s):  
Akira Saito ◽  
Kento Nakagawa ◽  
Yohei Masugi ◽  
Kimitaka Nakazawa
Keyword(s):  
Lower Limb ◽  
Motor Evoked Potentials ◽  
Voluntary Contraction ◽  
Spinal Reflex ◽  
Posterior Root ◽  
Antagonist Muscle ◽  
Lower Limb Muscles ◽  
Limb Muscles ◽  
Agonist And Antagonist ◽  
Muscle Reflexes

AbstractVoluntary contraction facilitates corticospinal and spinal reflex circuit excitabilities of the contracted muscle and inhibits spinal reflex circuit excitability of the antagonist. It has been suggested that modulation of spinal reflex circuit excitability in agonist and antagonist muscles during voluntary contraction differs among lower-limb muscles. However, whether the effects of voluntary contraction on the excitabilities of corticospinal and spinal reflex circuits depend on the tested muscles remains unknown. The purpose of this study was to examine inter-muscle differences in modulation of the corticospinal and spinal reflex circuit excitabilities of multiple lower-limb muscles during voluntary contraction. Eleven young males performed isometric plantar-flexion, dorsi-flexion, knee extension, and flexion at low torque levels. Motor evoked potentials (MEPs) and posterior root-muscle reflexes from seven lower-leg and thigh muscles were evoked by transcranial magnetic stimulation and transcutaneous spinal cord stimulation, respectively, at rest and during weak voluntary contractions. MEP and posterior root-muscle reflex amplitudes of agonists were significantly increased as agonist torque level increased, except for the reflex of the tibialis anterior. MEP amplitudes of antagonists were significantly increased in relation to the agonist torque level, but those of the rectus femoris were slightly depressed during knee flexion. Regarding the posterior root-muscle reflex of the antagonists, the amplitudes of triceps surae and the hamstrings were significantly decreased, but those of the quadriceps femoris were significantly increased as the agonist torque level increased. These results demonstrate that modulation of corticospinal and spinal reflex circuit excitabilities during agonist and antagonist muscle contractions differed among lower-limb muscles.

scholarly journals Characterization of Motor-Evoked Responses Obtained with Transcutaneous Electrical Spinal Stimulation from the Lower-Limb Muscles after Stroke

2021 ◽  
Vol 11 (3) ◽  
pp. 289
Author(s):  
Yaejin Moon ◽  
Taylor Zuleger ◽  
Martina Lamberti ◽  
Ashir Bansal ◽  
Chaithanya K. Mummidisetty ◽  
...  
Keyword(s):  
Lower Limb ◽  
Medial Gastrocnemius ◽  
Stroke Survivors ◽  
Evoked Responses ◽  
Lower Limb Muscles ◽  
Spinal Motor ◽  
Paretic Side ◽  
Resting Motor Threshold ◽  
Limb Muscles ◽  
Stroke Group

An increasing number of studies suggests that a novel neuromodulation technique targeting the spinal circuitry enhances gait rehabilitation, but research on its application to stroke survivors is limited. Therefore, we investigated the characteristics of spinal motor-evoked responses (sMERs) from lower-limb muscles obtained by transcutaneous spinal cord stimulation (tSCS) after stroke compared to age-matched and younger controls without stroke. Thirty participants (ten stroke survivors, ten age-matched controls, and ten younger controls) completed the study. By using tSCS applied between the L1 and L2 vertebral levels, we compared sMER characteristics (resting motor threshold (RMT), slope of the recruitment curve, and latency) of the tibialis anterior (TA) and medial gastrocnemius (MG) muscles among groups. A single pulse of stimulation was delivered in 5 mA increments, increasing from 5 mA to 250 mA or until the subjects reached their maximum tolerance. The stroke group had an increased RMT (27–51%) compared to both age-matched (TA: p = 0.032; MG: p = 0.005) and younger controls (TA: p < 0.001; MG: p<0.001). For the TA muscle, the paretic side demonstrated a 13% increased latency compared to the non-paretic side in the stroke group (p = 0.010). Age-matched controls also exhibited an increased RMT compared to younger controls (TA: p = 0.002; MG: p = 0.007), suggesting that altered sMER characteristics present in stroke survivors may result from both stroke and normal aging. This observation may provide implications for altered spinal motor output after stroke and demonstrates the feasibility of using sMER characteristics as an assessment after stroke.

Early and late motor evoked potentials reflect preset agonist-antagonist organization in lower limb muscles

1995 ◽  
Vol 18 (3) ◽  
pp. 276-282 ◽  
Author(s):  
Ina M. Tarkka ◽  
W. Barry McKay ◽  
Arthur M. Sherwood ◽  
Milan R. Dimitrijevic
Keyword(s):  
Evoked Potentials ◽  
Lower Limb ◽  
Motor Evoked Potentials ◽  
Lower Limb Muscles ◽  
Limb Muscles

scholarly journals Effects of neuromuscular electrical stimulation and voluntary commands on the spinal reflex excitability of remote limb muscles

2019 ◽  
Vol 237 (12) ◽  
pp. 3195-3205 ◽  
Author(s):  
Tatsuya Kato ◽  
Atsushi Sasaki ◽  
Hikaru Yokoyama ◽  
Matija Milosevic ◽  
Kimitaka Nakazawa
Keyword(s):  
Electrical Stimulation ◽  
Upper Limb ◽  
Lower Limb ◽  
Neuromuscular Electrical Stimulation ◽  
Voluntary Contraction ◽  
Spinal Reflex ◽  
Sensory Level ◽  
Reflex Excitability ◽  
Lower Limb Muscles ◽  
Limb Muscles

Abstract It is well known that contracting the upper limbs can affect spinal reflexes of the lower limb muscle, via intraneuronal networks within the central nervous system. However, it remains unknown whether neuromuscular electrical stimulation (NMES), which can generate muscle contractions without central commands from the cortex, can also play a role in such inter-limb facilitation. Therefore, the objective of this study was to compare the effects of unilateral upper limb contractions using NMES and voluntary unilateral upper limb contractions on the inter-limb spinal reflex facilitation in the lower limb muscles. Spinal reflex excitability was assessed using transcutaneous spinal cord stimulation (tSCS) to elicit responses bilaterally in multiple lower limb muscles, including ankle and thigh muscles. Five interventions were applied on the right wrist flexors for 70 s: (1) sensory-level NMES; (2) motor-level NMES; (3) voluntary contraction; (4) voluntary contraction and sensory-level NMES; (5) voluntary contraction and motor-level NMES. Results showed that spinal reflex excitability of ankle muscles was facilitated bilaterally during voluntary contraction of the upper limb unilaterally and that voluntary contraction with motor-level NMES had similar effects as just contracting voluntarily. Meanwhile, motor-level NMES facilitated contralateral thigh muscles, and sensory-level NMES had no effect. Overall, our results suggest that inter-limb facilitation effect of spinal reflex excitability in lower limb muscles depends, to a larger extent, on the presence of the central commands from the cortex during voluntary contractions. However, peripheral input generated by muscle contractions using NMES might have effects on the spinal reflex excitability of inter-limb muscles via spinal intraneuronal networks.

scholarly journals Task-specific changes in motor evoked potentials of lower limb muscles after different training interventions

2007 ◽  
Vol 1179 ◽  
pp. 51-60 ◽  
Author(s):  
S. Beck ◽  
W. Taube ◽  
M. Gruber ◽  
F. Amtage ◽  
A. Gollhofer ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Lower Limb ◽  
Motor Evoked Potentials ◽  
Training Interventions ◽  
Lower Limb Muscles ◽  
Limb Muscles

Validity of Skeletal Muscle Ultrasound in Assessment of Suspected Limb Girdle Muscular Dystrophy Patients

QJM ◽  
2021 ◽  
Vol 114 (Supplement_1) ◽  
Author(s):  
Rasha M Ibrahim ◽  
Haitham M Hamdy ◽  
Amr A Mohammed ◽  
Ahmed M Elsadek ◽  
Ahmed M Bassiouny ◽  
...  
Keyword(s):  
Muscular Dystrophy ◽  
Upper Limb ◽  
Lower Limb ◽  
Limb Girdle Muscular Dystrophy ◽  
Ultrasound Images ◽  
General Electric ◽  
Cross Sectional ◽  
Lower Limb Muscles ◽  
Limb Muscles ◽  
Muscle Ultrasound

Abstract Background Limb-girdle muscular dystrophies (LGMDs) are a clinically and genetically heterogeneous group of disorders characterized by progressive muscle weakness and degenerative muscle changes. Studies have shown that ultrasound can be useful both for diagnosis and follow-up of LGMDs patients. Objectives This study aims to measure the sensitivity and the specificity of muscle ultrasound in assessment of suspected limb girdle muscular dystrophy patients. Subjects and Methods This cross-sectional descriptive study was conducted on Fifty-five patients with suspected LGMD from neuromuscular unit, myology clinic, Ain Shams University hospitals and eight healthy subjects. Age was above 2 years. Both sexes were included in the study. They underwent real-time B-mode ultrasonography performed with using Logiq p9 General Electric ultrasound machine and General Electric 7-11.5 MHZ linear array ultrasound probe. All ultrasound images have been obtained and scored by a single examiner and muscle echo intensity was visually graded semiquantitative according to Heckmatt's scale. The examiner was blinded to the muscle biopsy results and clinical evaluations. Results Statistical analysis revealed that the diagnostic performance of muscle US (Heckmatt’s score) in LGMD is most sensitive when calculated in all examined upper limb and lower limb muscles, followed by lower limb muscles alone. US of upper limb was found to be the least sensitive. Conclusions Muscle ultrasound is a practical and reproducible and valid tool that can be used in assessment of suspected LGMD patients.

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