scholarly journals Changes in corticospinal excitability during reach adaptation in force fields

2013 ◽  
Vol 109 (1) ◽  
pp. 124-136 ◽  
Author(s):  
Jean-Jacques Orban de Xivry ◽  
Mohammad Ali Ahmadi-Pajouh ◽  
Michelle D. Harran ◽  
Yousef Salimpour ◽  
Reza Shadmehr
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Corticospinal Excitability ◽  
Neural Basis ◽  
Key Factor ◽  
Gradual Group ◽  
Specific Increase ◽  
Stimulation Of

Both abrupt and gradually imposed perturbations produce adaptive changes in motor output, but the neural basis of adaptation may be distinct. Here, we measured the state of the primary motor cortex (M1) and the corticospinal network during adaptation by measuring motor-evoked potentials (MEPs) before reach onset using transcranial magnetic stimulation of M1. Subjects reached in a force field in a schedule in which the field was introduced either abruptly or gradually over many trials. In both groups, by end of the training, muscles that countered the perturbation in a given direction increased their activity during the reach (labeled as the on direction for each muscle). In the abrupt group, in the period before the reach toward the on direction, MEPs in these muscles also increased, suggesting a direction-specific increase in the excitability of the corticospinal network. However, in the gradual group, these MEP changes were missing. After training, there was a period of washout. The MEPs did not return to baseline. Rather, in the abrupt group, off direction MEPs increased to match on direction MEPs. Therefore, we observed changes in corticospinal excitability in the abrupt but not gradual condition. Abrupt training includes the repetition of motor commands, and repetition may be the key factor that produces this plasticity. Furthermore, washout did not return MEPs to baseline, suggesting that washout engaged a new network that masked but did not erase the effects of previous adaptation. Abrupt but not gradual training appears to induce changes in M1 and/or corticospinal networks.

scholarly journals Associatively-mediated suppression of corticospinal excitability: A transcranial magnetic stimulation (TMS) study

2019 ◽  
Author(s):  
Manuel S. Seet ◽  
Evan J. Livesey ◽  
Justin A. Harris
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Response Inhibition ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Human Subjects ◽  
Stop Signal ◽  
Corticospinal Excitability ◽  
Stop Signal Task

AbstractResponse inhibition—the suppression of prepotent behaviours when they are inappropriate— has been thought to rely on executive control. Against this received wisdom, it has been argued that external cues repeatedly associated with response inhibition can come to trigger response inhibition automatically without top-down command. The current project endeavoured to provide evidence for associatively-mediated motor inhibition. We tested the hypothesis that stop-associated stimuli can, in a bottom-up fashion, directly activate inhibitory mechanisms in the motor cortex. Human subjects were first trained on a stop-signal task. Once trained, the subjects received transcranial magnetic stimulation applied over their primary motor cortex during passive observation of either the stop signal (i.e. without any need to stop a response) or an equally familiar control stimulus never associated with stopping. Analysis of motor-evoked potentials showed that corticospinal excitability was reduced during exposure to the stop signal, which likely involved stimulus-driven activation of intracortical GABAergic interneurons. This result offers evidence for the argument that, through associative learning, stop-associated stimuli can engage local inhibitory processes at the level of the motor cortex.

scholarly journals Motor Cortical Plasticity Induced by Volitional Muscle Activity-Triggered Transcranial Magnetic Stimulation and Median Nerve Stimulation

2021 ◽  
Vol 12 (1) ◽  
pp. 61
Author(s):  
Pramudika Nirmani Kariyawasam ◽  
Shinya Suzuki ◽  
Susumu Yoshida
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Nerve Stimulation ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Short Interval ◽  
Corticospinal Excitability ◽  
Motor Training ◽  
Median Nerve Stimulation ◽  
Bilateral Movement

Bilateral motor training is a useful method for modifying corticospinal excitability. The effects of bilateral movement that are caused by artificial stimulation on corticospinal excitability have not been reported. We compared motor-evoked potentials (MEPs) of the primary motor cortex (M1) after conventional bilateral motor training and artificial bilateral movements generated by electromyogram activity of abductor pollicis brevis (APB) muscle-triggered peripheral nerve stimulation (c-MNS) and transcranial magnetic stimulation of the ipsilateral M1 (i-TMS). A total of three protocols with different interventions—bilateral finger training, APB-triggered c-MNS, and APB-triggered i-TMS—were administered to 12 healthy participants. Each protocol consisted of 360 trials of 30 min for each trial. MEPs that were induced by single-pulse TMS, short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF) that were induced by paired-pulse TMS were assessed as outcome measures at baseline and at 0, 20, 40, and 60 min after intervention. MEP amplitude significantly increased up to 40 min post-intervention in all protocols compared to that at the baseline, although there were some differences in the changing pattern of ICF and SICI in each protocol. These findings suggest that artificial bilateral movement has the potential to increase the ipsilateral cortical excitability of the moving finger.

Increased corticospinal excitability prior to arm cycling is due to enhanced supraspinal but not spinal motoneurone excitability

2013 ◽  
Vol 38 (11) ◽  
pp. 1154-1161 ◽  
Author(s):  
Kevin E. Power ◽  
David B. Copithorne
Keyword(s):  
Magnetic Stimulation ◽  
Corticospinal Tract ◽  
Biceps Brachii ◽  
Motor Evoked Potentials ◽  
Corticospinal Excitability ◽  
Quiescent State ◽  
M Wave ◽  
Arm Cycling ◽  
Intention To Move ◽  
Stimulation Of

Human studies have not assessed supraspinal or spinal motoneurone excitability in the quiescent state prior to a rhythmic and alternating cyclical motor output. The purpose of the current study was to determine whether supraspinal and (or) spinal motoneurone excitability was modulated in humans prior to arm cycling when compared with rest with no intention to move. We hypothesized that corticospinal excitability would be enhanced prior to arm cycling due, in part, to increased spinal motoneurone excitability. Supraspinal and spinal motoneurone excitability were assessed via transcranial magnetic stimulation (TMS) of the motor cortex and transmastoid stimulation of the corticospinal tract, respectively. Surface electromyography recordings of TMS motor evoked potentials (MEPs) and cervicomedullary MEPs (CMEPs) were made from the relaxed biceps brachii muscle prior to rhythmic arm cycling and at rest with no intention to move. The amplitude of the MEPs was greater (mean increase: +9.8% of maximal M wave; p = 0.006) and their onset latencies were shorter (mean decrease: –1.5 ms; p < 0.05) prior to cycling when compared with rest. The amplitudes of the CMEPs at any of 3 stimulation intensities were not different between conditions. We conclude that premovement enhancement of corticospinal excitability is greater prior to arm cycling than at rest because of increases in supraspinal but not spinal motoneurone excitability.

The effect of transcranial magnetic stimulation on the excitability of the motor neuron pools of the muscles of the lower extremities

2021 ◽  
Author(s):  
S.S. Ananiev ◽  
D.A. Pavlov ◽  
R.N. Yakupov ◽  
V.A. Golodnova ◽  
M.V. Balykin
Keyword(s):  
Spinal Cord ◽  
Electrical Stimulation ◽  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Lower Extremities ◽  
Transcutaneous Electrical Stimulation ◽  
Stimulation Of

The study was conducted on 22 healthy men aged 18-23 years. The primary motor cortex innervating the lower limb was stimulated with transcranial magnetic stimulation. Using transcutaneous electrical stimulation of the spinal cord, evoked motor responses of the muscles of the lower extremities were initiated when electrodes were applied cutaneous between the spinous processes in the Th11-Th12 projection. Research protocol: Determination of the thresholds of BMO of the muscles of the lower extremities during TESCS; determination of the BMO threshold of the TA muscle in TMS; determination of the thresholds of the BMO of the muscles of the lower extremities during TESCS against the background of 80% and 90% TMS. It was found that magnetic stimulation of the motor cortex of the brain leads to an increase in the excitability of the neural structures of the lumbar thickening of the spinal cord and an improvement in neuromuscular interactions. Key words: transcranial magnetic stimulation, transcutaneous electrical stimulation of the spinal cord, neural networks, excitability, neuromuscular interactions.

Influence of different transcranial magnetic stimulation current directions on the corticomotor control of lumbar erector spinae muscles during a static task

2021 ◽  
Author(s):  
Mikaël Desmons ◽  
Antoine Rohel ◽  
Amélie Desgagnés ◽  
Catherine Mercier ◽  
Hugo Massé-Alarie
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Erector Spinae ◽  
Recruitment Curve ◽  
Axial Muscles ◽  
Active Motor ◽  
Stimulation Current ◽  
Cortical Representations

Different directions of transcranial magnetic stimulation (TMS) can activate different neuronal circuits. While posteroanterior current (PA-TMS) depolarizes mainly interneurons in primary motor cortex (M1), an anteroposterior current (AP-TMS) has been suggested to activate different M1 circuits and perhaps axons from the premotor regions. Although M1 is also involved in the control of axial muscles, no study has explored if different current directions activate different M1 circuits that may have distinct functional role. The aim of the study was to compare the effect of different current directions (PA- and AP-TMS) on the corticomotor control and spatial cortical organisation of the lumbar erector spinae muscle (LES). Thirthy-four healthy participants were recruited for two independent experiments and LES motor-evoked potentials (MEP) were recorded. In experiment 1 (n=17), active motor threshold (AMT), MEP latencies, recruitment curve (90 to 160% AMT), excitatory and inhibitory intracortical mechanisms using paired-pulse TMS (80% followed by 120% AMT stimuli at 2-3-10 and 15ms inter-stimulus intervals) were tested using a double cone (n=12) and a figure-of-eight (n=5) coils. In experiment 2 (n=17), LES cortical representations were tested using PA- and AP-TMS. AMT was higher for AP- compared to PA-TMS (p=0.002). Longer latencies with AP-TMS were compared to PA-TMS (p=0.017). AP-TMS produced more inhibition compared to PA-TMS at 2ms and 3ms (p=0.010), but no difference was observed for longer intervals. No difference was found for recruitment curve and mapping. Those findings suggest that each PA- and AP-TMS may activate different cortical circuits controlling low back muscles as proposed for hand muscles.

Sign in / Sign up

Export Citation Format

Share Document