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.

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 Surround inhibition depends on the force exerted and is abnormal in focal hand dystonia

2009 ◽  
Vol 107 (5) ◽  
pp. 1513-1518 ◽  
Author(s):  
S. Beck ◽  
M. Schubert ◽  
S. Pirio Richardson ◽  
M. Hallett
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Neural Mechanism ◽  
Single Pulse ◽  
Movement Initiation ◽  
Focal Hand Dystonia ◽  
Surround Inhibition ◽  
Hand Dystonia

There is evidence that surround inhibition (SI), a neural mechanism to enhance contrast between signals, may play a role in primary motor cortex during movement initiation, while it is deficient in patients with focal hand dystonia (FHD). To further characterize SI with respect to different force levels, single- and paired-pulse transcranial magnetic stimulation was applied at rest and during index finger movement to evoke potentials in the nonsynergistic, abductor policis muscle. In Experiment 1, in 19 healthy volunteers, SI was tested using single-pulse transcranial magnetic stimulation. Motor-evoked potentials at rest were compared with those during contraction using four different force levels [5, 10, 20, and 40% of maximum force (Fmax)]. In Experiments 2 and 3, SI and short intracortical inhibition (SICI) were tested, respectively, in 16 patients with FHD and 20 age-matched controls for the 10% and 20% Fmax levels. SI was most pronounced for 10% Fmax and abolished for the 40% Fmax level in controls, whereas FHD patients had no SI at all. In contrast, a loss of SICI was observed in FHD patients, which was more pronounced for 10% Fmax than for 20% Fmax. Our results suggest that SI is involved in the generation of fine finger movements with low-force levels. The greater loss of SICI for the 10% Fmax level in patients with FHD than for the 20% Fmax level indicates that this inhibitory mechanism is more abnormal at lower levels of force.

scholarly journals Hemodynamic changes in response to excitatory and inhibitory modulations by transcranial magnetic stimulation at the human sensorimotor cortex

2020 ◽  
Author(s):  
Hsin-Ju Lee ◽  
Mikko Nyrhinen ◽  
Risto J. Ilmoniemi ◽  
Fa-Hsuan Lin
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Low Frequency ◽  
Magnetic Resonance Images ◽  
Sensorimotor Network ◽  
Fmri Signal ◽  
Signal Changes ◽  
Neurophysiological Basis

AbstractTranscranial magnetic stimulation (TMS) can non-invasively induce both excitatory and inhibitory neuronal activity. However, the neurophysiological basis for both kinds of modulation remains elusive. In this study, with a controlled dosage over the 30-s interval, we elicited excitatory and inhibitory TMS modulations over the human primary motor cortex (M1) with TMS bursts of high (10-Hz and 30-Hz) and low frequency (0.5-Hz), respectively, and took functional magnetic resonance images (fMRI). Excitatory and inhibitory modulations were evidenced by changes in motor evoked potentials (MEP). Significantly increased fMRI signal at M1 was only detected under excitatory high-frequency TMS but not during inhibitory low-frequency TMS. The supplementary motor area (SMA) had significant fMRI signal changes after both excitatory and inhibitory TMS. The topology of the activated M1 and SMA matched the activated sensorimotor network during voluntary movement. The precuneus was selectively activated with bursts of five TMS pulses. These findings demonstrated the asymmetric hemodynamic responses to excitatory and inhibitory TMS modulations with region-dependent relationships between the local fMRI signal changes and TMS dosage over different time scales.

scholarly journals A new protocol for multiple muscle mapping using nTMS

2021 ◽  
Author(s):  
Fang Jin ◽  
Sjoerd M Bruijn ◽  
Andreas Daffertshofer
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Single Pulse ◽  
Cortical Representation ◽  
Precentral Gyrus ◽  
Validity And Reliability ◽  
Non Invasive ◽  
Centre Of Gravity

Background: Single-pulse transcranial magnetic stimulation is a safe and non-invasive tool for investigating cortical representation of muscles in the primary motor cortex. While non-navigated TMS has been successfully applied to simultaneously induce motor-evoked potentials (MEPs) in multiple muscles, a more rigorous assessment of the corresponding cortical representation can greatly benefit from navigated transcranial magnetic stimulation (nTMS). Objective: We designed a protocol to map the entire precentral gyrus using neural navigation while recording responses of eight muscles simultaneously. Here, we evaluated the feasibility, validity, and reliability of this protocol. Method: Twenty participants underwent conventional (i.e., muscle-based, grid-constrained) and gyrus-based nTMS mapping. For both protocols, we investigated three different stimulation intensities during two consecutive sessions. Results: The gyrus-based nTMS mapping was received well by all participants and was less time consuming than the grid-constrained standard. On average, MEP amplitudes, latencies, and centre-of-gravity and size of the active areas largely agreed across protocols supporting validity. Intraclass coefficients between sessions unscored the reliability of our protocol. Conclusion: We designed an nTMS protocol for the simultaneous mapping multiple muscles on the cortex. The protocol takes only about ten minutes per participant when including as many as eight muscles. Our assessments revealed that the cortical representation of multiple muscles can be determined with high validity and reliability.

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

2021 ◽  
Vol 14 (6) ◽  
pp. 1594
Author(s):  
Mikaël Desmons ◽  
Antoine Rohel ◽  
Amélie Desgagnés ◽  
Catherine Mercier ◽  
Hugo Massé-Alarie
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Erector Spinae ◽  
Stimulation Current

Facilitatory conditioning of the supplementary motor area in humans enhances the corticophrenic responsiveness to transcranial magnetic stimulation

2010 ◽  
Vol 108 (1) ◽  
pp. 39-46 ◽  
Author(s):  
Mathieu Raux ◽  
Haiqun Xie ◽  
Thomas Similowski ◽  
Lisa Koski
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Time Course ◽  
Primary Motor Cortex ◽  
Supplementary Motor Area ◽  
Motor Evoked Potentials ◽  
Motor Area ◽  
Motor Threshold ◽  
Functional Connection ◽  
Resting Motor Threshold

Inspiratory loading in awake humans is associated with electroencephalographic signs of supplementary motor area (SMA) activation. To provide evidence for a functional connection between SMA and the diaphragm representation in the primary motor cortex (M1DIA), we tested the hypothesis that modulating SMA activity using repetitive transcranial magnetic stimulation (rTMS) would alter M1DIA excitability. Amplitude and latency of diaphragm motor evoked potentials (MEPDIA), evoked through single pulse M1DIA stimulation, before and up to 16 min after SMA stimulation, were taken as indicators of M1DIA excitability. MEPs from the first dorsal interosseous muscle (FDI, MEPFDI) served as a control. Four SMA conditioning sessions were performed in random order at 1-wk intervals. Two aimed at increasing SMA activity (5 and 10 Hz, both at 110% of FDI active motor threshold; referred to as 5Hz and 10Hz, respectively), and two aimed at decreasing it (1 Hz either at 110% of FDI active or resting motor threshold, referred to as aMT or rMT, respectively). The 5Hz protocol increased MEPDIA and MEPFDI amplitudes with a maximum 11–16 min poststimulation ( P = 0.04 and P = 0.02, respectively). The 10Hz protocol increased MEPFDI amplitude with a similar time course ( P = 0.03) but did not increase MEPDIA amplitude ( P = 0.32). Both aMT and rMT failed to decrease MEPDIA or MEPFDI amplitudes ( P = 0.23 and P = 0.90, respectively, for diaphragm and P = 0.48 and P = 0.14 for FDI). MEPDIA and MEPFDI latencies were unaffected by rTMS. These results demonstrate that 5-Hz rTMS over the SMA can increase the excitability of M1DIA. These observations are consistent with the hypothesis of a functional connection between SMA and M1DIA.

Transcranial Magnetic Stimulation Study of Plastic Changes of Human Motor Cortex after Repetitive Simple Muscle Contractions

2002 ◽  
Vol 95 (3) ◽  
pp. 699-705 ◽  
Author(s):  
Shikako Hayashi ◽  
Yoshiteru Hasegawa ◽  
Tatsuya Kasai
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Structural Changes ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Human Subjects ◽  
Motor Evoked Potential ◽  
Neural Activation ◽  
Human Motor Cortex

Studies of use-dependent changes in neural activation have recently focused on the primary motor cortex. To detect the excitability changes in the primary motor cortex after practice in human subjects, motor-evoked potentials by transcranial magnetic stimulation during motor imagery after just 10 sessions of simple index finger abduction were examined. The present results indicate that width of the output map and amplitudes of motor-evoked potential became progressively larger until practice ended. These flexible short-term modulations of human primary motor cortex seem important and could lead to structural changes in the intracortical networks as the skill becomes more learned and automatic, i.e., ‘adaptation’ as one of the neural mechanisms related to motor learning.

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