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 Intra-limb modulations of posterior root-muscle reflexes evoked from the lower-limb muscles during isometric voluntary contractions

2021 ◽  
Author(s):  
Akira Saito ◽  
Kento Nakagawa ◽  
Yohei Masugi ◽  
Kimitaka Nakazawa
Keyword(s):  
Lower Limb ◽  
Motor Evoked Potential ◽  
Biceps Femoris ◽  
Knee Extension ◽  
Spinal Reflex ◽  
Posterior Root ◽  
Lower Limb Muscles ◽  
Limb Muscles ◽  
Voluntary Contractions ◽  
Muscle Reflexes

AbstractAlthough voluntary muscle contraction modulates spinal reflex excitability of contracted muscles and other muscles located at other segments within a limb (i.e., intra-limb modulation), to what extent corticospinal pathways are involved in intra-limb modulation of spinal reflex circuits remains unknown. The purpose of the present study was to identify differences in the involvement of corticospinal pathways in intra-limb modulation of spinal reflex circuits among lower-limb muscles during voluntary contractions. Ten young males performed isometric plantar-flexion, dorsi-flexion, knee extension, and knee flexion at 10% of each maximal torque. Electromyographic activity was recorded from soleus, tibialis anterior, vastus lateralis, and biceps femoris muscles. Motor evoked potentials and posterior root-muscle reflexes during rest and isometric contractions were elicited from the lower-limb muscles using transcranial magnetic stimulation and transcutaneous spinal cord stimulation, respectively. Motor evoked potential and posterior root-muscle reflex amplitudes of soleus during knee extension were significantly increased compared to rest. The motor evoked potential amplitude of biceps femoris during dorsi-flexion was significantly increased, whereas the posterior root-muscle reflex amplitude of biceps femoris during dorsi-flexion was significantly decreased compared to rest. These results suggest that corticospinal and spinal reflex excitabilities of soleus are facilitated during knee extension, whereas intra-limb modulation of biceps femoris during dorsi-flexion appeared to be inverse between corticospinal and spinal reflex circuits.

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 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.

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 Muscle-Specific Modulation of Spinal Reflexes in Lower-Limb Muscles during Action Observation with and without Motor Imagery of Walking

2019 ◽  
Vol 9 (12) ◽  
pp. 333 ◽  
Author(s):  
Kaneko ◽  
Masugi ◽  
Usuda ◽  
Yokoyama ◽  
Nakazawa
Keyword(s):  
Motor Imagery ◽  
Lower Limb ◽  
Tibialis Anterior ◽  
Action Observation ◽  
Spinal Reflexes ◽  
Spinal Reflex ◽  
Medial Gastrocnemius ◽  
Combined Processes ◽  
Lower Limb Muscles ◽  
Limb Muscles

Action observation (AO) and motor imagery (MI) are useful techniques in neurorehabilitation. Previous studies have reported that AO and MI facilitate corticospinal excitability only in those muscles that are active when actually performing the observed or imagined movements. However, it remained unclear whether spinal reflexes modulate multiple muscles simultaneously. The present study focused on AO and MI of walking and aimed to clarify their effects on spinal reflexes in lower-limb muscles that are recruited during actual walking. Ten healthy males participated in the present study. Spinal reflex parameters evoked by transcutaneous spinal cord stimulation were measured from five lower-limb muscles during rest, AO, and AO combined with MI (AO + MI) conditions. Our results showed that spinal reflexes were increased in the tibialis anterior and biceps femoris muscles during AO and in the tibialis anterior, soleus, and medial gastrocnemius muscles during AO + MI, compared with resting condition. Spinal reflex parameters in the vastus medialis muscle were unchanged. These results indicate the muscle-specific modulations of spinal reflexes during AO and AO + MI. These findings reveal the underlying neural activities induced by AO, MI, and their combined processes.

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

Evaluation of Descending Spinal Cord Tracts in Patients With Thoracic Cord Lesions Using Motor Evoked Potentials Recorded From the Paravertebral and Lower Limb Muscles

2003 ◽  
Vol 16 (2) ◽  
pp. 163-170 ◽  
Author(s):  
Taku Ogura ◽  
Hiroshi Takeshita ◽  
Hitoshi Hase ◽  
Taturo Hayashida ◽  
Masaki Mori ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Lower Limb ◽  
Motor Evoked Potentials ◽  
Lower Limb Muscles ◽  
Limb Muscles ◽  
Thoracic Cord

scholarly journals Using transcranial magnetic stimulation to map the cortical representation of lower-limb muscles

2019 ◽  
Author(s):  
Jennifer L Davies
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Lower Limb ◽  
Magnetic Stimulation ◽  
Motor Evoked Potentials ◽  
The Body ◽  
Double Cone ◽  
Cortical Representation ◽  
Lower Limb Muscles ◽  
Main Effect ◽  
Limb Muscles

AbstractThe aim of this study was to evaluate the extent to which transcranial magnetic stimulation (TMS) can identify discrete cortical representation of lower-limb muscles in healthy individuals. Data were obtained from 16 young healthy adults (12 women, four men; mean [SD] age 23.0 [2.6] years). Motor evoked potentials were recorded from the resting vastus medialis, rectus femoris, vastus lateralis, medial and lateral hamstring, and medial and lateral gastrocnemius muscles on the right side of the body using bipolar surface electrodes. TMS was delivered through a 110-mm double-cone coil at 63 sites over the left hemisphere. Location and size of the cortical representation and the number of discrete peaks were quantified for each muscle. Within the quadriceps muscle group there was a main effect of muscle on anterior-posterior centre of gravity (p = 0.010), but the magnitude of the difference was very small. Within the quadriceps there was a main effect of muscle on medial-lateral hotspot (p = 0.027) and map volume (p = 0.047), but no post-hoc tests were significant. The topography of each lower-limb muscle was complex, displaying multiple peaks that were present across the stimulation grid, and variable across individuals. The results of this study indicate that TMS delivered with a 110-mm double-cone coil could not reliably identify discrete cortical representations of resting lower-limb muscles when responses were measured using bipolar surface electromyography. The characteristics of the cortical representation of lower-limb muscles reported here provide a basis against which to evaluate cortical reorganisation in clinical populations.

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