scholarly journals A Bayesian approach to analysing cortico-cortical associative stimulation induced increases in the excitability of corticospinal projections in humans

2020 ◽  
Author(s):  
Richard G. Carson ◽  
Antonio Capozio ◽  
Emmet McNickle ◽  
Alexander T. Sack
Keyword(s):  
Primary Motor Cortex ◽  
Corticospinal Excitability ◽  
Effect Sizes ◽  
Motor Threshold ◽  
Resting Motor Threshold ◽  
Novel Variants ◽  
Separate Condition ◽  
Transcranial Alternating Current Stimulation ◽  
Descending Volleys ◽  
Left And Right

Abstract Repeated pairing of transcranial magnetic stimulation (TMS) over left and right primary motor cortex (M1), at intensities sufficient to generate descending volleys, produces sustained increases in corticospinal excitability. In other paired associative stimulation (PAS) protocols, in which peripheral afferent stimulation is the first element, changes in corticospinal excitability achieved when the second stimulus consists of brief bursts of transcranial alternating current stimulation (tACS), are comparable to those obtained if TMS is used instead (McNickle and Carson 2015). The present aim was to determine whether associative effects are induced when the first stimulus of a cortico-cortical pair is tACS, or alternatively subthreshold TMS. Bursts of tACS (500 ms; 140 Hz; 1 mA) were associated (180 stimulus pairs) with single magnetic stimuli (120% resting motor threshold rMT) delivered over the opposite (left) M1. The tACS ended 6 ms prior to the TMS. In a separate condition, TMS (55% rMT) was delivered to right M1 6 ms before (120% rMT) TMS was applied over left M1. In a sham condition, TMS (120% rMT) was delivered to left M1 only. The limitations of null hypothesis significance testing are well documented. We therefore employed Bayes factors to assess evidence in support of experimental hypotheses—defined precisely in terms of predicted effect sizes, that these two novel variants of PAS increase corticospinal excitability. Although both interventions induced sustained (~ 20–30 min) increases in corticospinal excitability, the evidence in support of the experimental hypotheses (over specified alternatives) was generally greater for the paired TMS-TMS than the tACS-TMS conditions.

Electroacupuncture modulates cortical excitability in a manner dependent on the parameters used

2021 ◽  
pp. 096452842110575
Author(s):  
Francisco Xavier de Brito ◽  
Cleber Luz-Santos ◽  
Janine Ribeiro Camatti ◽  
Rodrigo Jorge de Souza da Fonseca ◽  
Giovana Suzarth ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Primary Motor Cortex ◽  
Motor Evoked Potential ◽  
Corticospinal Excitability ◽  
Control Group ◽  
Sensory Threshold ◽  
Intensity Level ◽  
Dominant Hand ◽  
Motor Threshold ◽  
Resting Motor Threshold

Introduction: There is evidence that electroacupuncture (EA) acts through the modulation of brain activity, but little is known about its influence on corticospinal excitability of the primary motor cortex (M1). Objective: To investigate the influence of EA parameters on the excitability of M1 in healthy individuals. Methods: A parallel, double blind, randomized controlled trial in healthy subjects, evaluating the influence of an EA intervention on M1 excitability. Participants had a needle inserted at LI4 in the dominant hand and received electrical stimulation of different frequencies (10 or 100 Hz) and amplitude (sensory or motor threshold) for 20 min. In the control group, only a brief (30 s) electrical stimulation was applied. Single and paired pulse transcranial magnetic stimulation coupled with electromyography was applied before and immediately after the EA intervention. Resting motor threshold, motor evoked potential, short intracortical inhibition and intracortical facilitation were measured. Results: EA increased corticospinal excitability of M1 compared to the control group only when administered with a frequency of 100 Hz at the sensory threshold ( p < 0.05). There were no significant changes in the other measures. Conclusion: The results suggest that EA with an intensity level at the sensorial threshold and 100 Hz frequency increases the corticospinal excitability of M1. This effect may be associated with a decrease in the activity of inhibitory intracortical mechanisms. Trial registration number: U1111-1173-1946 (Registro Brasileiro de Ensaios Clínicos; http://www.ensaiosclinicos.gov.br/ )

scholarly journals No impact of functional connectivity of the motor system on the resting motor threshold: A replication study

2020 ◽  
Author(s):  
Melina Engelhardt ◽  
Darko Komnenić ◽  
Fabia Roth ◽  
Leona Kawelke ◽  
Carsten Finke ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Premotor Cortex ◽  
Corticospinal Excitability ◽  
Grey Matter Volume ◽  
Dominant Hemisphere ◽  
Motor Threshold ◽  
Dorsal Premotor Cortex ◽  
Resting Motor Threshold

AbstractThe physiological mechanisms of corticospinal excitability and factors influencing its measurement with transcranial magnetic stimulation are still poorly understood. A recent study reported an impact of functional connectivity between the primary motor cortex and dorsal premotor cortex on the resting motor threshold of the dominant hemisphere. We aimed to replicate these findings in a larger sample of 38 healthy right-handed subjects with data from both hemispheres. Resting-state functional connectivity was assessed between the primary motor cortex and five a-priori defined motor-relevant regions on each hemisphere as well as interhemispherically between both primary motor cortices. Following the procedure by the original authors, we included age, the cortical grey matter volume and coil to cortex distance as further predictors in the analysis. We report replication models for the dominant hemisphere as well as an extension to data from both hemispheres and support the results with Bayes factors. Functional connectivity between the primary motor cortex and dorsal premotor cortex did not explain variability in the resting motor threshold and we obtained moderate evidence for the absence of this effect. In contrast, coil to cortex distance could be confirmed as an important predictor with strong evidence. These findings contradict the previously proposed effect, thus questioning the notion of the dorsal premotor cortex playing a major role in modifying corticospinal excitability.

scholarly journals No Impact of Functional Connectivity of the Motor System on the Resting Motor Threshold: A Replication Study

2021 ◽  
Vol 15 ◽  
Author(s):  
Melina Engelhardt ◽  
Darko Komnenić ◽  
Fabia Roth ◽  
Leona Kawelke ◽  
Carsten Finke ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Primary Motor Cortex ◽  
Premotor Cortex ◽  
Gray Matter Volume ◽  
A Priori ◽  
Corticospinal Excitability ◽  
Dominant Hemisphere ◽  
Motor Threshold ◽  
Resting Motor Threshold ◽  
Cortical Gray Matter

The physiological mechanisms of corticospinal excitability and factors influencing its measurement with transcranial magnetic stimulation are still poorly understood. A recent study reported an impact of functional connectivity (FC) between the primary motor cortex (M1) and the dorsal premotor cortex (PMd) on the resting motor threshold (RMT) of the dominant hemisphere. We aimed to replicate these findings in a larger sample of 38 healthy right-handed subjects with data from both hemispheres. Resting-state FC was assessed between the M1 and five a priori defined motor-relevant regions on each hemisphere as well as interhemispherically between both primary motor cortices. Following the procedure by the original authors, we included age, cortical gray matter volume, and coil-to-cortex distance (CCD) as further predictors in the analysis. We report replication models for the dominant hemisphere as well as an extension to data from both hemispheres and support the results with Bayes factors. FC between the M1 and the PMd did not explain the variability in the RMT, and we obtained moderate evidence for the absence of this effect. In contrast, CCD could be confirmed as an important predictor with strong evidence. These findings contradict the previously proposed effect, thus questioning the notion of the PMd playing a major role in modifying corticospinal excitability.

scholarly journals The Corticospinal Excitability Can Be Predicted by Spontaneous Electroencephalography Oscillations

2021 ◽  
Vol 15 ◽  
Author(s):  
Guiyuan Cai ◽  
Manfeng Wu ◽  
Qian Ding ◽  
Tuo Lin ◽  
Wanqi Li ◽  
...  
Keyword(s):  
Brain Network ◽  
Corticospinal Excitability ◽  
Network Activity ◽  
Motor Threshold ◽  
Global Efficiency ◽  
Sensorimotor Region ◽  
Resting Motor Threshold ◽  
Wide Range ◽  
Active Motor ◽  
Selection Operator

Transcranial magnetic stimulation (TMS) has a wide range of clinical applications, and there is growing interest in neural oscillations and corticospinal excitability determined by TMS. Previous studies have shown that corticospinal excitability is influenced by fluctuations of brain oscillations in the sensorimotor region, but it is unclear whether brain network activity modulates corticospinal excitability. Here, we addressed this question by recording electroencephalography (EEG) and TMS measurements in 32 healthy individuals. The resting motor threshold (RMT) and active motor threshold (AMT) were determined as markers of corticospinal excitability. The least absolute shrinkage and selection operator (LASSO) was used to identify significant EEG metrics and then correlation analysis was performed. The analysis revealed that alpha2 power in the sensorimotor region was inversely correlated with RMT and AMT. Innovatively, graph theory was used to construct a brain network, and the relationship between the brain network and corticospinal excitability was explored. It was found that the global efficiency in the theta band was positively correlated with RMT. Additionally, the global efficiency in the alpha2 band was negatively correlated with RMT and AMT. These findings indicated that corticospinal excitability can be modulated by the power spectrum in sensorimotor regions and the global efficiency of functional networks. EEG network analysis can provide a useful supplement for studying the association between EEG oscillations and corticospinal excitability.

scholarly journals Repetitive Transcranial Magnetic Stimulation for Dysesthesia Caused by Subacute Myelo-Optico-Neuropathy: A Case Report

2020 ◽  
Vol 12 (2) ◽  
pp. 169-174
Author(s):  
Tomoo Mano ◽  
Satoshi Kuru
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Lower Limbs ◽  
Antibacterial Drug ◽  
Motor Threshold ◽  
Neuromuscular Dysfunction ◽  
Resting Motor Threshold ◽  
Sensory Disturbances

Subacute myelo-optico-neuropathy (SMON) is caused by the ingestion of clioquinol (5-chloro-7-iodo-8-hydroxyquinoline), which is an intestinal antibacterial drug. Patients with SMON typically suffer from abnormal dysesthesia in the lower limbs, which cannot explain the mechanism only in pathology and electrophysiology. Neuromodulation therapies are increasingly being investigated as a means of alleviating abnormal sensory disturbances. We report here the response to repetitive transcranial magnetic stimulation (rTMS) for dysesthesia in a patient with SMON. The patient underwent rTMS treatment once per week for 12 weeks. rTMS was administered at 10 Hz, 90% of the resting motor threshold over the bilateral primary motor cortex foot area, for a total of 1,500 stimuli per day. After the treatment had finished at 12 weeks, the abnormal dysesthesia gradually declined. At first, there were improvements only in the area with a feeling of adherence. Later, this sensation was eliminated. Three months following the application, most of the feeling of adherence had disappeared and the feeling of tightness was slightly reduced. In contrast, the throbbing feeling had not changed during this period. Dysesthesia may indicate a process of central sensitization, which would contribute to chronic neuromuscular dysfunction. This case suggests that rTMS is a promising therapeutic application for dysesthesia.

scholarly journals Comparison of low frequency repetitive transcranial magnetic stimulation parameters on motor cortex excitability in normal subjects

2016 ◽  
Vol 03 (01) ◽  
pp. 002-006
Author(s):  
Lara Schrader ◽  
Sima Sadeghinejad ◽  
Jalleh Sadeghinejad ◽  
Movses Kazanchyan ◽  
Lisa Koski ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Low Frequency ◽  
Motor Threshold ◽  
Motor Cortex Excitability ◽  
Resting Motor Threshold

Abstract Background/objectives Optimal low frequency repetitive transcranial magnetic stimulation (LF-rTMS) parameters for treating epilepsy and other brain disorders are unknown. To address this question, a systematic study of the effects of LF-rTMS frequency and intensity on cortical excitability was performed. Methods Using a four-period crossover design, subjects were scheduled for four LF-rTMS sessions that were at least four weeks apart. LF-rTMS was delivered as 900 pulses directed at primary motor cortex using four protocols: 0.5 Hz at 90% resting motor threshold (RMT), 0.5 Hz at 110% RMT, 1 Hz at 90% RMT, and 1 Hz at 110% RMT. Motor evoked potential (MEP) amplitude, resting motor threshold (RMT), and cortical silent period (CSP) were measured before, immediately after, and 60 min after LF-rTMS. Each of the four protocols was analyzed separately to compare baseline measurements to those after LF-rTMS. Results None of the four LF-rTMS protocols produced a trend or significant change in MEP amplitude, RMT, or CSP. Conclusion The lack of significant effect from the four LF-rTMS protocols indicates that none produced evidence for alteration of cortical excitability. The direct comparison of four LF-rTMS protocols is distinct to this investigation, as most similar studies were exploratory and studied only one or two protocols. The negative result relates only to the methods used in this investigation and does not indicate that LF-rTMS does not alter cortical excitability with other parameters. These results may be useful when designing additional investigations into the effect of LF-rTMS on epilepsy, other disorders, and cortical excitability.

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

2020 ◽  
Author(s):  
Pramudika Nirmani Kariyawasam ◽  
Shinya Suzuki ◽  
Susumu Yoshida
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Median Nerve ◽  
Nerve Stimulation ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Short Interval ◽  
Corticospinal Excitability ◽  
Post Intervention ◽  
Median Nerve Stimulation ◽  
Resting Motor Threshold

Abstract BackgroundBilateral motor training (BMT) is a useful method to modify the excitability of the corticospinal system. The effects of artificial symmetrical movement on corticospinal excitability through functional electrical stimulation (FES) or transcranial magnetic stimulation (TMS) have not been reported. Therefore, we compared motor-evoked potentials (MEPs) following TMS over the ipsilateral primary motor cortex (M1) of voluntary movements after conventional BMT and repetitive artificial symmetrical movements generated through FES and TMS.MethodsSurface electromyograms of the abductor pollicis brevis (APB) muscles were recorded bilaterally in 12 healthy participants. Three sessions with different protocols were conducted: (1) bilateral finger training (BFT) involving bilateral thumb abduction, (2) right APB-triggered TMS of the ipsilateral M1 (APB-triggered i-TMS), and (3) right APB-triggered contralateral median nerve stimulation (APB-triggered c-MNS). Each protocol consisted of 360 trials for 30 min. Resting motor threshold (RMT), MEPs induced by single-pulse TMS, short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF) induced by paired-pulse TMS were assessed as outcome measures at baseline and at 0, 20, 40, and 60 min after intervention.ResultsRMT showed no significant effect of intervention, time, or interaction. MEP amplitude showed a significant effect with time. MEP amplitude significantly increased at 0, 20, and 40 min post-intervention in BFT; at 0, 20, 40, and 60 min post-intervention in APB-triggered i-TMS; and at 20 and 40 min post-intervention in APB-triggered c-MNS in comparison to the baseline values. SICI was significantly decreased at 0 min post-intervention in the BFT and APB-triggered i-TMS protocols. ICF was significantly increased at 0 min post-intervention in the BFT and at 20 min post-intervention in the APB-triggered c-MNS protocol.ConclusionThe main finding of the present study was the long-lasting increase in MEP amplitude in all three mirror-symmetrical movement protocols. The observed changes are long-lasting and comparatively strong. However, the underlying neural mechanisms seem to be slightly different across the three protocols. Thus, whether voluntarily or artificially caused, repetitive symmetrical mirror movements enhance corticospinal excitability.

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.

scholarly journals Transcutaneous spinal direct current stimulation modulates human corticospinal system excitability

2015 ◽  
Vol 114 (1) ◽  
pp. 440-446 ◽  
Author(s):  
Tommaso Bocci ◽  
Sara Marceglia ◽  
Maurizio Vergari ◽  
Valeria Cognetto ◽  
Filippo Cogiamanian ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Direct Current ◽  
Lower Limb ◽  
Motor Evoked Potentials ◽  
H Reflex ◽  
Corticospinal Excitability ◽  
Motor Threshold ◽  
Abductor Hallucis ◽  
Direct Current Stimulation ◽  
Resting Motor Threshold

This study aimed to assess the effects of thoracic anodal and cathodal transcutaneous spinal direct current stimulation (tsDCS) on upper and lower limb corticospinal excitability. Although there have been studies assessing how thoracic tsDCS influences the spinal ascending tract and reflexes, none has assessed the effects of this technique over upper and lower limb corticomotor neuronal connections. In 14 healthy subjects we recorded motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) from abductor hallucis (AH) and hand abductor digiti minimi (ADM) muscles before (baseline) and at different time points (0 and 30 min) after anodal or cathodal tsDCS (2.5 mA, 20 min, T9–T11 level). In 8 of the 14 subjects we also tested the soleus H reflex and the F waves from AH and ADM before and after tsDCS. Both anodal and cathodal tsDCS left the upper limb MEPs and F wave unchanged. Conversely, while leaving lower limb H reflex unchanged, they oppositely affected lower limb MEPs: whereas anodal tsDCS increased resting motor threshold [(mean ± SE) 107.33 ± 3.3% increase immediately after tsDCS and 108.37 ± 3.2% increase 30 min after tsDCS compared with baseline] and had no effects on MEP area and latency, cathodal tsDCS increased MEP area (139.71 ± 12.9% increase immediately after tsDCS and 132.74 ± 22.0% increase 30 min after tsDCS compared with baseline) without affecting resting motor threshold and MEP latency. Our results show that tsDCS induces polarity-specific changes in corticospinal excitability that last for >30 min after tsDCS offset and selectively affect responses in lower limb muscles innervated by lumbar and sacral motor neurons.

Motor cortex disinhibition in normal-pressure hydrocephalus

2012 ◽  
Vol 116 (2) ◽  
pp. 453-459 ◽  
Author(s):  
Andrei V. Chistyakov ◽  
Hava Hafner ◽  
Alon Sinai ◽  
Boris Kaplan ◽  
Menashe Zaaroor
Keyword(s):  
Motor Cortex ◽  
Healthy Volunteers ◽  
Normal Pressure Hydrocephalus ◽  
Close Association ◽  
Motor Evoked Potential ◽  
Normal Pressure ◽  
Corticospinal Excitability ◽  
Conduction Time ◽  
Shunt Placement ◽  
Resting Motor Threshold

Object Previous studies have shown a close association between frontal lobe dysfunction and gait disturbance in idiopathic normal-pressure hydrocephalus (iNPH). A possible mechanism linking these impairments could be a modulation of corticospinal excitability. The aim of this study was 2-fold: 1) to determine whether iNPH affects corticospinal excitability; and 2) to evaluate changes in corticospinal excitability following ventricular shunt placement in relation to clinical outcome. Methods Twenty-three patients with iNPH were examined using single- and paired-pulse transcranial magnetic stimulation of the leg motor area before and 1 month after ventricular shunt surgery. The parameters of corticospinal excitability assessed were the resting motor threshold (rMT), motor evoked potential/M-wave area ratio, central motor conduction time, intracortical facilitation, and short intracortical inhibition (SICI). The results were compared with those obtained in 8 age-matched, healthy volunteers, 19 younger healthy volunteers, and 9 age-matched patients with peripheral neuropathy. Results Significant reduction of the SICI associated with a decrease of the rMT was observed in patients with iNPH at baseline evaluation. Ventricular shunt placement resulted in significant enhancement of the SICI and increase of the rMT in patients who markedly improved, but not in those who failed to improve. Conclusions This study demonstrates that iNPH affects corticospinal excitability, causing disinhibition of the motor cortex. Recovery of corticospinal excitability following ventricular shunt placement is correlated with clinical improvement. These findings support the view that reduced control of motor output, rather than impairment of central motor conduction, is responsible for gait disturbances in patients with iNPH.

Sign in / Sign up

Export Citation Format

Share Document