Resting and active motor thresholds versus stimulus–response curves to determine transcranial magnetic stimulation intensity in quadriceps femoris

Temesi, John; Gruet, Mathieu; Rupp, Thomas; Vergès, Samuel; Millet, Guillaume Y.

doi:10.1186/1743-0003-11-40

Cited by 73 publications

(53 citation statements)

References 53 publications

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“…A stimulus–response curve at 20% MVC was used to determine optimal TMS intensity, as recently described by Temesi et al . (). Subjects performed brief contractions (∼2–3 s) at 20% MVC of the knee extensors with TMS delivered four consecutive times at each of the following randomly ordered stimulus intensities: 20, 30, 40, 50, 60, 70 and 80% maximal stimulator output.…”

Section: Methodsmentioning

confidence: 97%

“…During all voluntary contractions, TMS was delivered once the subject had contracted to the appropriate force level and the force had stabilized (Gruet et al 2013b). A stimulus-response curve at 20% MVC was used to determine optimal TMS intensity, as recently described by Temesi et al (2014a). Subjects performed brief contractions (ß2-3 s) at 20% MVC of the knee extensors with TMS delivered four consecutive times at each of the following randomly ordered stimulus intensities: 20, 30, 40, 50, 60, 70 and 80% maximal stimulator output.…”

Section: Motor Cortical Stimulationmentioning

confidence: 99%

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Dynamics of corticospinal changes during and after high‐intensity quadriceps exercise

Gruet

Temesi

Rupp

et al. 2014

Experimental Physiology

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New FindingsOur results show that single-joint knee-extensor isometric exercise induces late supraspinal fatigue with increased intracortical inhibition, both of which recover quickly after task failure, and unchanged corticospinal excitability. This indicates that fatigue-induced corticospinal changes are muscle and/or limb specific and reinforces the need to measure corticospinal changes within seconds after task failure to avoid their underestimation. This study tested the hypothesis that during fatiguing quadriceps exercise, supraspinal fatigue develops late, is associated with both increased corticospinal excitability and inhibition and recovers quickly. Eight subjects performed 20 s contractions [15 s at 50% maximal voluntary contraction (MVC) followed by 5 s MVC] separated by a 10 s rest period until task failure. Transcranial magnetic stimulation (TMS) and electrical femoral nerve stimulation (PNS) were delivered ß2 s apart during 50% MVC, during MVC and after MVC in relaxed muscle. Voluntary activation was assessed by TMS (VA TMS ) immediately before and after exercise and then three times over a 6 min recovery period. During exercise, MVC and twitch force evoked by PNS in relaxed muscle decreased progressively to 48 ± 8 and 36 ± 16% of control values, respectively (both P < 0.01). Significant changes in voluntary activation assessed by PNS and twitch evoked by TMS during MVC were observed during the last quarter of exercise only (from 96.4 ± 1.7 to 86 ± 13%, P = 0.03 and from 0.76 ± 0.8 to 4.9 ± 4.7% MVC, P = 0.02, from baseline to task failure, respectively). The TMS-induced silent period increased linearly during both MVC (by ß79 ms) and 50% MVC (by ß63 ms; both P < 0.01). Motor-evoked potential amplitude did not change during the protocol at any force levels. Both silent period and VA TMS recovered within M. Gruet and others 2 min postexercise, whereas MVC and twitch force evoked by PNS in relaxed muscle recovered to only 84 ± 9 and 73 ± 17% of control values 6 min after exercise, respectively. In conclusion, high-intensity single-joint quadriceps exercise induces supraspinal fatigue near task failure, with increased intracortical inhibition and, in contrast to previous upper-limb results, unchanged corticospinal excitability. These changes recover rapidly after task failure, emphasizing the need to measure corticospinal adaptations immediately at task failure to avoid underestimation of exercise-induced corticospinal changes.

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Section: Methodsmentioning

confidence: 97%

Section: Motor Cortical Stimulationmentioning

confidence: 99%

Dynamics of corticospinal changes during and after high‐intensity quadriceps exercise

Gruet

Temesi

Rupp

et al. 2014

Experimental Physiology

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“…Then markers were positioned over the participant and over the coil to maintain the coil location. After that, a recruitment curve was performed during voluntary contraction, at 10% of the maximal quadriceps torque, in order to determine the maximal intensity (noted I Mep ) [40]. One pulse was delivered every 10 s with increasing intensity in steps of 2% until the highest response was obtained.…”

Section: Evaluation Of Corticospinal Excitability By Transcranial Magmentioning

confidence: 99%

Specific motor cortex hypoexcitability and hypoactivation in COPD patients with peripheral muscle weakness

Alexandre

Héraud²,

Tremey³

et al. 2020

BMC Pulm Med

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Background: Peripheral muscle weakness can be caused by both peripheral muscle and neural alterations. Although peripheral alterations cannot totally explain peripheral muscle weakness in COPD, the existence of an activation deficit remains controversial. The heterogeneity of muscle weakness (between 32 and 57% of COPD patients) is generally not controlled in studies and could explain this discrepancy. This study aimed to specifically compare voluntary and stimulated activation levels in COPD patients with and without muscle weakness. Methods: Twenty-two patients with quadriceps weakness (COPD MW), 18 patients with preserved quadriceps strength (COPD NoMW) and 20 controls were recruited. Voluntary activation was measured through peripheral nerve (VA peripheral) and transcranial magnetic (VA cortical) stimulation. Corticospinal and spinal excitability (MEP/Mmax and Hmax/Mmax) and corticospinal inhibition (silent period duration) were assessed during maximal voluntary quadriceps contractions. Results: COPD MW exhibited lower VA cortical and lower MEP/Mmax compared with COPD NoMW (p < 0.05). Hmax/Mmax was not significantly different between groups (p = 0.25). Silent period duration was longer in the two groups of COPD patients compared with controls (p < 0.01). Interestingly, there were no significant differences between all COPD patients taken together and controls regarding VA cortical and MEP/Mmax. Conclusions: COPD patients with muscle weakness have reduced voluntary activation without altered spinal excitability. Corticospinal inhibition is higher in COPD regardless of muscle weakness. Therefore, reduced cortical excitability and a voluntary activation deficit from the motor cortex are the most likely cortical mechanisms implicated in COPD muscle weakness. The mechanisms responsible for cortical impairment and possible therapeutic interventions need to be addressed.

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“…The hot spot, ineon, and vertex were drawn with a permanent marker on a swimming cap, in order to ensure repeatability between sessions. After locating the hot spot, the resting motor threshold (RMT), defined as the stimulation intensity that elicits MEPs of ∼50 µV peak-to-peak amplitude in 5 out of 10 applied pulses (Temesi et al, 2014), was set for each participant. We recorded ipsilaterally (Kamibayashi et al, 2009) TAnt and Soleus (SO), as well as Rectus Femoris (RF, as a control muscle not involved in the robotic ankle task).…”

Section: Neurophysiological Assessmentmentioning

confidence: 99%

Haptic Adaptive Feedback to Promote Motor Learning With a Robotic Ankle Exoskeleton Integrated With a Video Game

Asín-Prieto

Martínez-Expósito

Barroso

et al. 2020

Front. Bioeng. Biotechnol.

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Background: Robotic devices have been used to rehabilitate walking function after stroke. Although results suggest that post-stroke patients benefit from this non-conventional therapy, there is no agreement on the optimal robot-assisted approaches to promote neurorecovery. Here we present a new robotic therapy protocol using a grounded exoskeleton perturbing the ankle joint based on tacit learning control. Method: Ten healthy individuals and a post-stroke patient participated in the study and were enrolled in a pilot intervention protocol that involved performance of ankle movements following different trajectories via video game visual feedback. The system autonomously modulated task difficulty according to the performance to increase the challenge. We hypothesized that motor learning throughout training sessions would lead to increased corticospinal excitability of dorsi-plantarflexor muscles. Transcranial Magnetic Stimulation was used to assess the effects on corticospinal excitability. Results: Improvements have been observed on task performance and motor outcomes in both healthy individuals and post-stroke patient case study. Tibialis Anterior corticospinal excitability increased significantly after the training; however no significant changes were observed on Soleus corticospinal excitability. Clinical scales showed functional improvements in the stroke patient. Discussion and Significance: Our findings both in neurophysiological and performance assessment suggest improved motor learning. Some limitations of the study include treatment duration and intensity, as well as the non-significant changes in corticospinal excitability obtained for Soleus. Nonetheless, results suggest that this robotic training framework is a potentially interesting approach that can be explored for gait rehabilitation in post-stroke patients.

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Resting and active motor thresholds versus stimulus–response curves to determine transcranial magnetic stimulation intensity in quadriceps femoris

Cited by 73 publications

References 53 publications

Dynamics of corticospinal changes during and after high‐intensity quadriceps exercise

Dynamics of corticospinal changes during and after high‐intensity quadriceps exercise

Specific motor cortex hypoexcitability and hypoactivation in COPD patients with peripheral muscle weakness

Haptic Adaptive Feedback to Promote Motor Learning With a Robotic Ankle Exoskeleton Integrated With a Video Game

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