scholarly journals Simulation of electromyographic recordings following transcranial magnetic stimulation

2018 ◽  
Vol 120 (5) ◽  
pp. 2532-2541 ◽  
Author(s):  
Bahar Moezzi ◽  
Natalie Schaworonkow ◽  
Lukas Plogmacher ◽  
Mitchell R. Goldsworthy ◽  
Brenton Hordacre ◽  
...  
Keyword(s):  
Experimental Data ◽  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Cortical Layer ◽  
Detailed Model ◽  
Emg Signal ◽  
Feed Forward Network ◽  
Layer 2

Transcranial magnetic stimulation (TMS) is a technique that enables noninvasive manipulation of neural activity and holds promise in both clinical and basic research settings. The effect of TMS on the motor cortex is often measured by electromyography (EMG) recordings from a small hand muscle. However, the details of how TMS generates responses measured with EMG are not completely understood. We aim to develop a biophysically detailed computational model to study the potential mechanisms underlying the generation of EMG signals following TMS. Our model comprises a feed-forward network of cortical layer 2/3 cells, which drive morphologically detailed layer 5 corticomotoneuronal cells, which in turn project to a pool of motoneurons. EMG signals are modeled as the sum of motor unit action potentials. EMG recordings from the first dorsal interosseous muscle were performed in four subjects and compared with simulated EMG signals. Our model successfully reproduces several characteristics of the experimental data. The simulated EMG signals match experimental EMG recordings in shape and size, and change with stimulus intensity and contraction level as in experimental recordings. They exhibit cortical silent periods that are close to the biological values and reveal an interesting dependence on inhibitory synaptic transmission properties. Our model predicts several characteristics of the firing patterns of neurons along the entire pathway from cortical layer 2/3 cells down to spinal motoneurons and should be considered as a viable tool for explaining and analyzing EMG signals following TMS. NEW & NOTEWORTHY A biophysically detailed model of EMG signal generation following transcranial magnetic stimulation (TMS) is proposed. Simulated EMG signals match experimental EMG recordings in shape and amplitude. Motor-evoked potential and cortical silent period properties match experimental data. The model is a viable tool to analyze, explain, and predict EMG signals following TMS.

Transcranial magnetic stimulation

2016 ◽  
Author(s):  
Kerry R. Mills
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Neurons ◽  
Magnetic Stimulation ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Demyelinating Diseases ◽  
Conduction Time ◽  
Spinal Motor Neurons ◽  
Basic Physics ◽  
Clinical Measures

Transcranial magnetic stimulation (TMS) has been exploited to advance knowledge of corticospinal physiology and, in a number of conditions, to aid diagnosis and quantify corticospinal abnormalities. The basic physics of magnetic stimulation is described along with the effects of stimulating coils with different dimensions and shape. The effects of single TMS pulses over motor cortex to cause a descending volley of D and I waves, and their effects on spinal motor neurons resulting in a motor evoked potential (MEP) are described. Guidelines for the safe use of TMS are given. Methods to estimate useful clinical measures of corticospinal function, such as threshold, MEP amplitude, central motor conduction time, silent period and input:output relation are given, as is the means to quantify corticospinal conduction using the triple stimulation technique. The clinical utility of TMS in neurodegenerations, central demyelinating diseases, stroke, spinal cord disease, movement disorders, and functional disorders is discussed.

scholarly journals Eight weeks of local vibration training increases dorsiflexor muscle cortical voluntary activation

2017 ◽  
Vol 122 (6) ◽  
pp. 1504-1515 ◽  
Author(s):  
Robin Souron ◽  
Adrien Farabet ◽  
Léonard Féasson ◽  
Alain Belli ◽  
Guillaume Y. Millet ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Output Curve ◽  
Input Output ◽  
Local Vibration ◽  
Vibration Training

The aim of this study was to evaluate the effects of an 8-wk local vibration training (LVT) program on functional and corticospinal properties of dorsiflexor muscles. Forty-four young subjects were allocated to a training (VIB, n = 22) or control (CON, n = 22) group. The VIB group performed twenty-four 1-h sessions (3 sessions/wk) of 100-Hz vibration applied to the right tibialis anterior. Both legs were tested in each group before training (PRE), after 4 (MID) and 8 (POST) wk of training, and 2 wk after training (POST2W). Maximal voluntary contraction (MVC) torque was assessed, and transcranial magnetic stimulation (TMS) was used to evaluate cortical voluntary activation (VATMS), motor evoked potential (MEP), cortical silent period (CSP), and input-output curve parameters. MVC was significantly increased for VIB at MID for right and left legs [+7.4% ( P = 0.001) and +6.2% ( P < 0.01), respectively] and remained significantly greater than PRE at POST [+12.0% ( P < 0.001) and +10.1% ( P < 0.001), respectively]. VATMS was significantly increased for right and left legs at MID [+4.4% ( P < 0.01) and +4.7% ( P < 0.01), respectively] and at POST [+4.9% ( P = 0.001) and +6.2% ( P = 0.001), respectively]. These parameters remained enhanced in both legs at POST2W. MEP and CSP recorded during MVC and input-output curve parameters did not change at any time point for either leg. Despite no changes in excitability or inhibition being observed, LVT seems to be a promising method to improve strength through an increase of maximal voluntary activation, i.e., neural adaptations. Local vibration may thus be further considered for clinical or aging populations. NEW & NOTEWORTHY The effects of a local vibration training program on cortical voluntary activation measured with transcranial magnetic stimulation were assessed for the first time in dorsiflexors, a functionally important muscle group. We observed that training increased maximal voluntary strength likely because of the strong and repeated activation of Ia spindle afferents during vibration training that led to changes in the cortico-motoneuronal pathway, as demonstrated by the increase in cortical voluntary activation.

Late Cortical Disinhibition in Human Motor Cortex: A Triple-Pulse Transcranial Magnetic Stimulation Study

2010 ◽  
Vol 103 (1) ◽  
pp. 511-518 ◽  
Author(s):  
R. F. H. Cash ◽  
U. Ziemann ◽  
K. Murray ◽  
G. W. Thickbroom
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Short Interval ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Intracortical Inhibition ◽  
Human Motor Cortex ◽  
Acid Type ◽  
Human Motor

In human motor cortex transcranial magnetic stimulation (TMS) has been used to identify short-interval intracortical inhibition (SICI) corresponding to γ-aminobutyric acid type A (GABAA) effects and long-interval intracortical inhibition (LICI) and the cortical silent period (SP) corresponding to postsynaptic GABAB effects. Presynaptic GABAB effects, corresponding to disinhibition, can also be identified with TMS and have been shown to be acting during LICI by measuring SICI after a suprathreshold priming stimulus (PS). The duration of disinhibition is not certain and, guided by studies in experimental preparations, we hypothesized that it may be longer-lasting than postsynaptic inhibition, leading to a period of late cortical disinhibition and consequently a net increase in corticospinal excitability. We tested this first by measuring the motor-evoked potential (MEP) to a test stimulus (TS), delivered after a PS at interpulse intervals (IPIs) ≤300 ms that encompassed the period of PS-induced LICI and its aftermath. MEP amplitude was initially decreased, but then increased at IPIs of 190–210 ms, reaching 160 ± 17% of baseline 200 ms after PS ( P < 0.05). SP duration was 181 ± 5 ms. A second experiment established that the onset of the later period of increased excitability correlated with PS intensity ( r2 = 0.99) and with the duration of the SP ( r2 = 0.99). The third and main experiment demonstrated that SICI was significantly reduced in strength at all IPIs ≤220 ms after PS. We conclude that TMS-induced LICI is associated with a period of disinhibition that is at first masked by LICI, but that outlasts LICI and gives rise to a period during which disinhibition predominates and net excitability is raised. Identification of this late period of disinhibition in human motor cortex may provide an opportunity to explore or modulate the behavior of excitatory networks at a time when inhibitory effects are restrained.

The effect of acetaminophen ingestion on cortico-spinal excitability

2013 ◽  
Vol 91 (2) ◽  
pp. 187-189 ◽  
Author(s):  
Alexis R. Mauger ◽  
James G. Hopker
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Evoked Potential ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Sodium Currents ◽  
Cortical Silent Period ◽  
Voltage Gated ◽  
Spinal Excitability

Acetaminophen (ACT) facilitates the inhibition of voltage-gated calcium and sodium currents, which may effect cortico-spinal excitability. Twelve subjects ingested acetaminophen or a placebo and underwent transcranial magnetic stimulation to assess the motor evoked potential (MEP), and cortical silent period (CSP). ACT significantly increased MEP response (P > 0.05) but had no effect on CSP (P > 0.05). This indicates that ACT increases MEP and should be controlled for in studies where these measures are of interest.

scholarly journals Cerebellar Transcranial Magnetic Stimulation Reduces the Silent Period on Hand Muscle Electromyography During Force Control

2020 ◽  
Vol 10 (2) ◽  
pp. 63 ◽  
Author(s):  
Akiyoshi Matsugi ◽  
Shinya Douchi ◽  
Kodai Suzuki ◽  
Kosuke Oku ◽  
Nobuhiko Mori ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Maximum Voluntary Contraction ◽  
Motor Evoked Potential ◽  
Silent Period ◽  
Voluntary Contraction ◽  
Resting Motor Threshold ◽  
First Dorsal Interosseous Muscle ◽  
The Right

This study aimed to investigate whether cerebellar transcranial magnetic stimulation (C-TMS) affected the cortical silent period (cSP) induced by TMS over the primary motor cortex (M1) and the effect of interstimulus interval (ISI) on cerebellar conditioning and TMS to the left M1 (M1-TMS). Fourteen healthy adult participants were instructed to control the abduction force of the right index finger to 20% of the maximum voluntary contraction. M1-TMS was delivered during this to induce cSP on electromyograph of the right first dorsal interosseous muscle. TMS over the right cerebellum (C-TMS) was conducted prior to M1-TMS. In the first experiment, M1-TMS intensity was set to 1 or 1.3 × resting motor threshold (rMT) with 20-ms ISI. In the second experiment, the intensity was set to 1 × rMT with ISI of 0, 10, 20, 30, 40, 50, 60, 70, or 80 ms, and no-C-TMS trials were inserted. In results, cSP was significantly shorter in 1 × rMT condition than in 1.3 × rMT by C-TMS, and cSP was significantly shorter for ISI of 20–40 ms than for the no-C-TMS condition. Further, motor evoked potential for ISI40-60 ms were significantly reduced than that for ISI0. Thus, C-TMS may reduce cSP induced by M1-TMS with ISI of 20–40 ms.

scholarly journals Motor disability in patients with multiple sclerosis: transcranial magnetic stimulation study

2020 ◽  
Vol 56 (1) ◽  
Author(s):  
Anssam Bassem Mohy ◽  
Aqeel Kareem Hatem ◽  
Hussein Ghani Kadoori ◽  
Farqad Bader Hamdan
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Lower Limb ◽  
Magnetic Stimulation ◽  
Motor Evoked Potential ◽  
Invasive Procedure ◽  
Single Pulse ◽  
Lower Limbs ◽  
Control Group ◽  
Conduction Time ◽  
Motor Disability

Abstract Background Transcranial magnetic stimulation (TMS) is a non-invasive procedure used in a small targeted region of the brain via electromagnetic induction and used diagnostically to measure the connection between the central nervous system (CNS) and skeletal muscle to evaluate the damage that occurs in MS. Objectives The study aims to investigate whether single-pulse TMS measures differ between patients with MS and healthy controls and to consider if these measures are associated with clinical disability. Patients and methods Single-pulse TMS was performed in 26 patients with MS who hand an Expanded Disability Status Scale (EDSS) score between 0 and 9.5 and in 26 normal subjects. Different TMS parameters from upper and lower limbs were investigated. Results TMS disclosed no difference in all MEP parameters between the right and left side of the upper and lower limbs in patients with MS and controls. In all patients, TMS parameters were different from the control group. Upper limb central motor conduction time (CMCT) was prolonged in MS patients with pyramidal signs. Upper and lower limb CMCT and CMCT-f wave (CMCT-f) were prolonged in patients with ataxia. Moreover, CMCT and CMCT-f were prolonged in MS patients with EDSS of 5–9.5 as compared to those with a score of 0–4.5. EDSS correlated with upper and lower limb cortical latency (CL), CMCT, and CMCT-f whereas motor evoked potential (MEP) amplitude not. Conclusion TMS yields objective data to evaluate clinical disability and its parameters correlated well with EDSS.

scholarly journals Intracortical and Intercortical Motor Disinhibition to Transcranial Magnetic Stimulation in Newly Diagnosed Celiac Disease Patients

Nutrients ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 1530
Author(s):  
Francesco Fisicaro ◽  
Giuseppe Lanza ◽  
Carmela Cinzia D’Agate ◽  
Raffaele Ferri ◽  
Mariagiovanna Cantone ◽  
...  
Keyword(s):  
Celiac Disease ◽  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Rating Scale ◽  
De Novo ◽  
Motor Evoked Potentials ◽  
Silent Period ◽  
Cross Sectional ◽  
Transcallosal Inhibition ◽  
Resting Motor Threshold

Background: Celiac disease (CD) may present or be complicated by neurological and neuropsychiatric manifestations. Transcranial magnetic stimulation (TMS) probes brain excitability non-invasively, also preclinically. We previously demonstrated an intracortical motor disinhibition and hyperfacilitation in de novo CD patients, which revert back after a long-term gluten-free diet (GFD). In this cross-sectional study, we explored the interhemispheric excitability by transcallosal inhibition, which has never been investigated in CD. Methods: A total of 15 right-handed de novo, neurologically asymptomatic, CD patients and 15 age-matched healthy controls were screened for cognitive and depressive symptoms to the Montreal Cognitive Assessment (MoCA) and the 17-item Hamilton Depression Rating Scale (HDRS), respectively. TMS consisted of resting motor threshold, amplitude, latency, and duration of the motor evoked potentials, duration and latency of the contralateral silent period (cSP). Transcallosal inhibition was evaluated as duration and latency of the ipsilateral silent period (iSP). Results: MoCA and HDRS scored significantly worse in patients. The iSP and cSP were significantly shorter in duration in patients, with a positive correlation between the MoCA and iSP. Conclusions: An intracortical and interhemispheric motor disinhibition was observed in CD, suggesting the involvement of GABA-mediated cortical and callosal circuitries. Further studies correlating clinical, TMS, and neuroimaging data are needed.

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