Repetitive Peripheral Magnetic Stimulation of Wrist Extensors Enhances Cortical Excitability and Motor Performance in Healthy Individuals

Repetitive peripheral magnetic stimulation (rPMS) may improve motor function following central nervous system lesions, but the optimal parameters of rPMS to induce neural plasticity and mechanisms underlying its action remain unclear. We examined the effects of rPMS over wrist extensor muscles on neural plasticity and motor performance in 26 healthy volunteers. In separate experiments, the effects of rPMS on motor evoked potentials (MEPs), short-interval intracortical inhibition (SICI), intracortical facilitation (ICF), direct motor response (M-wave), Hoffmann-reflex, and ballistic wrist extension movements were assessed before and after rPMS. First, to examine the effects of stimulus frequency, rPMS was applied at 50, 25, and 10 Hz by setting a fixed total number of stimuli. A significant increase in MEPs of wrist extensors was observed following 50 and 25 Hz rPMS, but not 10 Hz rPMS. Next, we examined the time required to induce plasticity by increasing the number of stimuli, and found that at least 15 min of 50 and 25 Hz rPMS was required. Based on these parameters, lasting effects were evaluated following 15 min of 50 or 25 Hz rPMS. A significant increase in MEP was observed up to 60 min following 50 and 25 Hz rPMS; similarly, an attenuation of SICI and enhancement of ICF were also observed. The maximal M-wave and Hoffmann-reflex did not change, suggesting that the increase in MEP was due to plastic changes at the motor cortex. This was accompanied by increasing force and electromyograms during wrist ballistic extension movements following 50 and 25 Hz rPMS. These findings suggest that 15 min of rPMS with 25 Hz or more induces an increase in cortical excitability of the relevant area rather than altering the excitability of spinal circuits, and has the potential to improve motor output.

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Distributed cortical structural properties contribute to motor cortical excitability and inhibition

10.1101/178301 ◽

2017 ◽

Author(s):

Eran Dayan ◽

Virginia López-Alonso ◽

Sook-Lei Liew ◽

Leonardo G. Cohen

Keyword(s):

Motor Cortex ◽

Structural Properties ◽

Motor Function ◽

Primary Motor Cortex ◽

Cortical Excitability ◽

Motor Evoked Potentials ◽

Short Interval ◽

Intracortical Inhibition ◽

Corticospinal Excitability ◽

Support Vector

AbstractThe link between the local structure of the primary motor cortex and motor function has been well documented. However, motor function relies on a network of interconnected brain regions and the link between the structural properties characterizing these distributed brain networks and motor function remains poorly understood. Here, we examined whether distributed patterns of brain structure, extending beyond the primary motor cortex can help classify two forms of motor function: corticospinal excitability and intracortical inhibition. To this effect, we recorded high-resolution structural magnetic resonance imaging scans in 25 healthy volunteers. To measure corticospinal excitability and inhibition in the same volunteers we recorded motor evoked potentials (MEPs) elicited by single-pulse transcranial magnetic stimulation (TMS) and short-interval intracortical inhibition (SICI) in a separate session. Support vector machine (SVM) pattern classification was used to identify distributed multivoxel gray matter areas, which distinguished subjects who had lower and higher MEPs and SICIs. We found that MEP and SICI classification could be predicted based on a widely distributed, largely non-overlapping pattern of voxels in the frontal, parietal, temporal, occipital and cerebellar regions. Thus, structural properties distributed over the brain beyond the primary motor cortex relate to motor function.

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Modulation of motor cortex neuronal networks by rTMS: comparison of local and remote effects of six different protocols of stimulation

Journal of Neurophysiology ◽

10.1152/jn.00781.2010 ◽

2011 ◽

Vol 105 (5) ◽

pp. 2150-2156 ◽

Cited By ~ 141

Author(s):

V. Di Lazzaro ◽

M. Dileone ◽

F. Pilato ◽

F. Capone ◽

G. Musumeci ◽

...

Keyword(s):

Motor Cortex ◽

Neuronal Networks ◽

Cortical Excitability ◽

Motor Evoked Potentials ◽

Repetitive Transcranial Magnetic Stimulation ◽

Short Interval ◽

Stimulus Frequency ◽

Silent Period ◽

Pronounced Increase ◽

Human Motor Cortex

Repetitive transcranial magnetic stimulation (rTMS) of human motor cortex can produce long-lasting changes in the excitability of excitatory and inhibitory neuronal networks. The effects of rTMS depend critically on stimulus frequency. The aim of our present study was to compare the effects of different rTMS protocols. We compared the aftereffects of 6 different rTMS protocols [paired associative stimulation at interstimulus intervals of 25 (PAS25) and 10 ms (PAS10); theta burst stimulation delivered as continuous (cTBS) or intermittent delivery pattern (iTBS); 1- and 5-Hz rTMS] on the excitability of stimulated and contralateral motor cortex in 10 healthy subjects. A pronounced increase of cortical excitability, evaluated by measuring the amplitude of motor evoked potentials (MEPs), was produced by iTBS (+56%) and PAS25 (+45%). Five-hertz rTMS did not produce a significant increase of MEPs. A pronounced decrease of cortical excitability was produced by PAS10 (−31%), cTBS (−29%), and 1-Hz rTMS (−20%). Short-interval intracortical inhibition was suppressed by PAS10. Cortical silent period duration was increased by 1-Hz stimulation. No significant effect was observed in the contralateral hemisphere. Head-to-head comparison of the different protocols enabled us to identify the most effective paradigms for modulating the excitatory and inhibitory circuits activated by TMS.

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Cortical excitability varies across different muscles

Journal of Neurophysiology ◽

10.1152/jn.00148.2018 ◽

2018 ◽

Vol 120 (3) ◽

pp. 1397-1403 ◽

Cited By ~ 7

Author(s):

Parvathi Menon ◽

Matthew C. Kiernan ◽

Steve Vucic

Keyword(s):

Transcranial Magnetic Stimulation ◽

Magnetic Stimulation ◽

Functional Organization ◽

Cortical Excitability ◽

Short Interval ◽

Intracortical Inhibition ◽

Body Regions ◽

Threshold Tracking ◽

Resting Motor Threshold ◽

Limb Muscles

The aim of the present study was to determine whether significant differences in cortical excitability were evident across different body regions in healthy humans. Threshold tracking transcranial magnetic stimulation (TMS) was undertaken in 28 healthy controls. Short-interval intracortical inhibition [SICI between interstimulus intervals (ISI) 1–7 ms], intracortical facilitation (ICF, between ISI 10–30 ms), resting motor threshold (RMT), cortical silent period (CSP) duration (generated at stimulus intensity 150% RMT), and motor evoked potential amplitude were recorded from the abductor pollicis brevis (APB), tibialis anterior (TA), and trapezius muscles. These muscles were selected as they are frequently affected in neurodegenerative diseases, such as amyotrophic lateral sclerosis. SICI and ICF are measured as a percentage difference between conditioned and an unconditioned test response. SICI was significantly greater when recorded over the APB (9.9 ± 1.5%) and TA (8.6 ± 1.4%) muscles compared with the trapezius (4.5 ± 1.9%, P < 0.05). The CSP duration was significantly shorter (CSPtrapezius, 131.0 ± 6.3 ms; CSPTA, 175.7 ± 9.9 ms; CSPAPB, 188.3 ± 4.0 ms; P < 0.001) and ICF greater ( P < 0.01) in the trapezius muscle. There were no significant correlations between inhibitory and facilitatory processes recorded across the three muscles. The present study established significant differences in cortical excitability across three body regions, with evidence of more prominent inhibition and less facilitation in the limb muscles. NEW & NOTEWORTHY Cortical excitability of muscles with differing motor functions was assessed using threshold tracking transcranial magnetic stimulation. Significantly greater intracortical inhibition and less facilitation were evident over the limb muscles. These findings could relate to differences in the functional organization of the corticomotoneuronal system innervating different muscle regions.

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Effects of the motor cortical quadripulse transcranial magnetic stimulation (QPS) on the contralateral motor cortex and interhemispheric interactions

Journal of Neurophysiology ◽

10.1152/jn.00515.2013 ◽

2014 ◽

Vol 111 (1) ◽

pp. 26-35 ◽

Cited By ~ 17

Author(s):

Ryosuke Tsutsumi ◽

Ritsuko Hanajima ◽

Yasuo Terao ◽

Yuichiro Shirota ◽

Shinya Ohminami ◽

...

Keyword(s):

Transcranial Magnetic Stimulation ◽

Corpus Callosum ◽

Magnetic Stimulation ◽

Motor Evoked Potentials ◽

Short Interval ◽

Long Term Potentiation ◽

Intracortical Inhibition ◽

Motor Threshold ◽

Resting Motor Threshold

Corpus callosum connects the bilateral primary motor cortices (M1s) and plays an important role in motor control. Using the paired-pulse transcranial magnetic stimulation (TMS) paradigm, we can measure interhemispheric inhibition (IHI) and interhemispheric facilitation (IHF) as indexes of the interhemispheric interactions in humans. We investigated how quadripulse transcranial magnetic stimulation (QPS), one form of repetitive TMS (rTMS), on M1 affects the contralateral M1 and the interhemispheric interactions. QPS is able to induce bidirectional plastic changes in M1 depending on the interstimulus intervals (ISIs) of TMS pulses: long-term potentiation (LTP)-like effect by QPS-5 protocol, and long-term depression-like effect by QPS-50, whose numbers indicate the ISI (ms). Twelve healthy subjects were enrolled. We applied QPS over the left M1 and recorded several parameters before and 30 min after QPS. QPS-5, which increased motor-evoked potentials (MEPs) induced by left M1 activation, also increased MEPs induced by right M1 activation. Meanwhile, QPS-50, which decreased MEPs elicited by left M1 activation, did not induce any significant changes in MEPs elicited by right M1 activation. None of the resting motor threshold, active motor threshold, short-interval intracortical inhibition, long-interval intracortical inhibition, intracortical facilitation, and short-interval intracortical inhibition in right M1 were affected by QPS. IHI and IHF from left to right M1 significantly increased after left M1 QPS-5. The degree of left first dorsal interosseous MEP amplitude change by QPS-5 significantly correlated with the degree of IHF change. We suppose that the LTP-like effect on the contralateral M1 may be produced by some interhemispheric interactions through the corpus callosum.

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Altered cortical excitability in persistent idiopathic facial pain

Cephalalgia ◽

10.1177/0333102418780426 ◽

2018 ◽

Vol 39 (2) ◽

pp. 219-228 ◽

Cited By ~ 2

Author(s):

Ricardo Galhardoni ◽

Daniel Ciampi de Andrade ◽

Mariana YT Puerta ◽

Andre R Brunoni ◽

Bruna LR Varotto ◽

...

Keyword(s):

Transcranial Magnetic Stimulation ◽

Facial Pain ◽

Magnetic Stimulation ◽

Cortical Excitability ◽

Motor Evoked Potentials ◽

Intracortical Inhibition ◽

Healthy Controls ◽

Persistent Idiopathic Facial Pain ◽

Pain Patients ◽

Pulse Stimulation

Introduction Persistent idiopathic facial pain is a refractory and disabling condition of unknown mechanism and etiology. It has been suggested that persistent idiopathic facial pain patients have not only peripheral generators of pain, but also central nervous system changes that would contribute to the persistence of symptoms. We hypothesized that persistent idiopathic facial pain would have changes in brain cortical excitability as measured by transcranial magnetic stimulation compared to healthy controls. Methods Twenty-nine persistent idiopathic facial pain patients were compared to age- and sex-matched healthy controls and underwent cortical excitability measurements by transcranial magnetic stimulation applied to the cortical representation of the masseter muscle of both hemispheres. Single-pulse stimulation was used to measure the resting motor threshold and suprathreshold motor-evoked potentials. Paired-pulse stimulation was used to assess short intracortical inhibition and intracortical facilitation. Clinical pain and associated symptoms were assessed with validated tools. Results Spontaneous pain was found in 27 (93.1%) and provoked pain was found in two (6.9%) persistent idiopathic facial pain patients. The motor-evoked potentials at 120% and 140% were significantly lower for both hemispheres compared to controls. Persistent idiopathic facial pain patients had lower short-interval intracortical inhibition compared with controls. These changes were correlated with some aspects of quality of life, and higher mood symptoms. These neurophysiological alterations were not influenced by analgesic medication, as similar changes were observed in patients with or without central-acting drugs. Conclusions Persistent idiopathic facial pain is associated with changes in intracortical modulation involving GABAergic mechanisms, which may be related to certain aspects of the pathophysiology of this chronic pain condition. Trial registration: NTC01746355.

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Magnifying the View of the Hand Changes Its Cortical Representation. A Transcranial Magnetic Stimulation Study

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_01266 ◽

2018 ◽

Vol 30 (8) ◽

pp. 1098-1107 ◽

Cited By ~ 1

Author(s):

Elisabetta Ambron ◽

Nicole White ◽

Olufunsho Faseyitan ◽

Sudha K. Kessler ◽

Jared Medina ◽

...

Keyword(s):

Transcranial Magnetic Stimulation ◽

Motor Cortex ◽

Magnetic Stimulation ◽

Motor Evoked Potentials ◽

Hot Spot ◽

Short Interval ◽

Body Part ◽

Intracortical Inhibition ◽

Cortical Representation ◽

Motor Cortex Excitability

Changes in the perceived size of a body part using magnifying lenses influence tactile perception and pain. We investigated whether the visual magnification of one's hand also influences the motor system, as indexed by transcranial magnetic stimulation (TMS)-induced motor evoked potentials (MEPs). In Experiment 1, MEPs were measured while participants gazed at their hand with and without magnification of the hand. MEPs were significantly larger when participants gazed at a magnified image of their hand. In Experiment 2, we demonstrated that this effect is specific to the hand that is visually magnified. TMS of the left motor cortex did not induce an increase of MEPs when participants looked at their magnified left hand. Experiment 3 was performed to determine if magnification altered the topography of the cortical representation of the hand. To that end, a 3 × 5 grid centered on the cortical hot spot (cortical location at which a motor threshold is obtained with the lowest level of stimulation) was overlaid on the participant's MRI image, and all 15 sites in the grid were stimulated with and without magnification of the hand. We confirmed the increase in the MEPs at the hot spot with magnification and demonstrated that MEPs significantly increased with magnification at sites up to 16.5 mm from the cortical hot spot. In Experiment 4, we used paired-pulse TMS to measure short-interval intracortical inhibition and intracortical facilitation. Magnification was associated with an increase in short-interval intracortical inhibition. These experiments demonstrate that the visual magnification of one's hand induces changes in motor cortex excitability and generates a rapid remapping of the cortical representation of the hand that may, at least in part, be mediated by changes in short-interval intracortical inhibition.

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Modulation of intracortical inhibition during physically performed and mentally simulated balance tasks

European Journal of Applied Physiology ◽

10.1007/s00421-020-04577-1 ◽

2021 ◽

Vol 121 (5) ◽

pp. 1379-1388

Author(s):

A. Mouthon ◽

J. Ruffieux ◽

W. Taube

Keyword(s):

Motor Evoked Potentials ◽

Action Observation ◽

Short Interval ◽

Intracortical Inhibition ◽

Mental Simulation ◽

Task Execution ◽

Postural Tasks ◽

Execution Condition ◽

The One ◽

Postural Task

Abstract Purpose Action observation (AO) during motor imagery (MI), so-called AO + MI, has been proposed as a new form of non-physical training, but the neural mechanisms involved remains largely unknown. Therefore, this study aimed to explore whether there were similarities in the modulation of short-interval intracortical inhibition (SICI) during execution and mental simulation of postural tasks, and if there was a difference in modulation of SICI between AO + MI and AO alone. Method 21 young adults (mean ± SD = 24 ± 6.3 years) were asked to either passively observe (AO) or imagine while observing (AO + MI) or physically perform a stable and an unstable standing task, while motor evoked potentials and SICI were assessed in the soleus muscle. Result SICI results showed a modulation by condition (F2,40 = 6.42, p = 0.009) with less SICI in the execution condition compared to the AO + MI (p = 0.009) and AO (p = 0.002) condition. Moreover, switching from the stable to the unstable stance condition reduced significantly SICI (F1,20 = 8.34, p = 0.009) during both, physically performed (− 38.5%; p = 0.03) and mentally simulated balance (− 10%, p < 0.001, AO + MI and AO taken together). Conclusion The data demonstrate that SICI is reduced when switching from a stable to a more unstable standing task during both real task execution and mental simulation. Therefore, our results strengthen and further support the existence of similarities between executed and mentally simulated actions by showing that not only corticospinal excitability is similarly modulated but also SICI. This proposes that the activity of the inhibitory cortical network during mental simulation of balance tasks resembles the one during physical postural task execution.

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Intracortical Inhibition During Volitional Inhibition of Prepared Action

Journal of Neurophysiology ◽

10.1152/jn.01334.2005 ◽

2006 ◽

Vol 95 (6) ◽

pp. 3371-3383 ◽

Cited By ~ 192

Author(s):

James P. Coxon ◽

Cathy M. Stinear ◽

Winston D. Byblow

Keyword(s):

Primary Motor Cortex ◽

Motor Evoked Potentials ◽

Short Interval ◽

Intracortical Inhibition ◽

Corticomotor Excitability ◽

Hand Muscles ◽

Cortical Level ◽

A Site ◽

Intrinsic Hand Muscles ◽

Inhibitory Networks

Volitional inhibition is the voluntary prevention of a prepared movement. Here we ask whether primary motor cortex (M1) is a site of convergence of cortical activity associated with movement preparation and volitional inhibition. Volitional inhibition was studied by presenting a stop signal before execution of an anticipated response that requires a key lift to intercept a revolving dial. Motor evoked potentials (MEPs) were elicited in intrinsic hand muscles by transcranial magnetic stimulation (TMS) to assess corticomotor excitability and short interval intracortical inhibition (sICI) during task performance. The closer the stop cue was presented to the anticipated response, the harder it was for subjects to inhibit their response. Corticomotor pathway excitability was temporally modulated during volitional inhibition. Using subthreshold TMS, corticomotor excitability was reduced for Stop trials relative to Go trials from 140 ms after the cue. sICI was significantly greater for Stop trials compared with Go trials at a time that preceded the onset of muscle activity associated with the anticipated response. These results provide evidence that volitional inhibition is exerted at a cortical level and that inhibitory networks within M1 contribute to volitional inhibition of prepared action.

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

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2013-0084 ◽

2013 ◽

Vol 38 (11) ◽

pp. 1154-1161 ◽

Cited By ~ 9

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.

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