Mirror illusion reduces motor cortical inhibition in the ipsilateral primary motor cortex during forceful unilateral muscle contractions

Forceful, unilateral contractions modulate corticomotor paths targeting the resting, contralateral hand. However, it is unknown whether mirror-viewing of a slowly moving but forcefully contracting hand would additionally affect these paths. Here we examined corticospinal excitability and short-interval intracortical inhibition (SICI) of the right-ipsilateral primary motor cortex (M1) in healthy young adults under no-mirror and mirror conditions at rest and during right wrist flexion at 60% maximal voluntary contraction (MVC). During the no-mirror conditions neither hand was visible, whereas in the mirror conditions participants looked at the right hand's reflection in the mirror. Corticospinal excitability increased during contractions in the left flexor carpi radialis (FCR) (contraction 0.41 mV vs. rest 0.21 mV) and extensor carpi radialis (ECR) (contraction 0.56 mV vs. rest 0.39 mV), but there was no mirror effect (FCR: P = 0.743, ηp2= 0.005; ECR: P = 0.712, ηp2= 0.005). However, mirror-viewing of the contracting and moving wrist attenuated SICI relative to test pulse in the left FCR by ∼9% compared with the other conditions ( P < 0.05, d ≥ 0.62). Electromyographic activity in the resting left hand prior to stimulation was not affected by the mirror (FCR: P = 0.255, ηp2= 0.049; ECR: P = 0.343, ηp2= 0.035) but increased twofold during contractions. Thus viewing the moving hand in the mirror and not just the mirror image of the nonmoving hand seems to affect motor cortical inhibitory networks in the M1 associated with the mirror image. Future studies should determine whether the use of a mirror could increase interlimb transfer produced by cross-education, especially in patient groups with unilateral orthopedic and neurological conditions.

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Differences between motor execution and motor imagery of grasping movements in the motor cortical excitatory circuit

PeerJ ◽

10.7717/peerj.5588 ◽

2018 ◽

Vol 6 ◽

pp. e5588 ◽

Cited By ~ 2

Author(s):

Hai-Jiang Meng ◽

Yan-Ling Pi ◽

Ke Liu ◽

Na Cao ◽

Yan-Qiu Wang ◽

...

Keyword(s):

Motor Cortex ◽

Motor Imagery ◽

Primary Motor Cortex ◽

Cortical Excitability ◽

Short Interval ◽

Corticospinal Excitability ◽

Motor Execution ◽

Human Motor Cortex ◽

Motor Cortical ◽

The Right

Background Both motor imagery (MI) and motor execution (ME) can facilitate motor cortical excitability. Although cortical excitability is modulated by intracortical inhibitory and excitatory circuits in the human primary motor cortex, it is not clear which intracortical circuits determine the differences in corticospinal excitability between ME and MI. Methods We recruited 10 young healthy subjects aged 18−28 years (mean age: 22.1 ± 3.14 years; five women and five men) for this study. The experiment consisted of two sets of tasks involving grasp actions of the right hand: imagining and executing them. Corticospinal excitability and short-interval intracortical inhibition (SICI) were measured before the interventional protocol using transcranial magnetic stimulation (baseline), as well as at 0, 20, and 40 min (T0, T20, and T40) thereafter. Results Facilitation of corticospinal excitability was significantly greater after ME than after MI in the right abductor pollicis brevis (APB) at T0 and T20 (p < 0.01 for T0, and p < 0.05 for T20), but not in the first dorsal interosseous (FDI) muscle. On the other hand, no significant differences in SICI between ME and MI were found in the APB and FDI muscles. The facilitation of corticospinal excitability at T20 after MI correlated with the Movement Imagery Questionnaire (MIQ) scores for kinesthetic items (Rho = −0.646, p = 0.044) but did not correlate with the MIQ scores for visual items (Rho = −0.265, p = 0.458). Discussion The present results revealed significant differences between ME and MI on intracortical excitatory circuits of the human motor cortex, suggesting that cortical excitability differences between ME and MI may be attributed to the activation differences of the excitatory circuits in the primary motor cortex.

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Transcranial static magnetic stimulation over the motor cortex can facilitate the contralateral cortical excitability in human

Scientific Reports ◽

10.1038/s41598-021-84823-4 ◽

2021 ◽

Vol 11 (1) ◽

Cited By ~ 2

Author(s):

Yasuyuki Takamatsu ◽

Satoko Koganemaru ◽

Tatsunori Watanabe ◽

Sumiya Shibata ◽

Yoshihiro Yukawa ◽

...

Keyword(s):

Motor Cortex ◽

Magnetic Stimulation ◽

Primary Motor Cortex ◽

Cortical Excitability ◽

Motor Evoked Potentials ◽

Single Pulse ◽

Brain Network ◽

Corticospinal Excitability ◽

Double Blind ◽

The Right

AbstractTranscranial static magnetic stimulation (tSMS) has been focused as a new non-invasive brain stimulation, which can suppress the human cortical excitability just below the magnet. However, the non-regional effects of tSMS via brain network have been rarely studied so far. We investigated whether tSMS over the left primary motor cortex (M1) can facilitate the right M1 in healthy subjects, based on the hypothesis that the functional suppression of M1 can cause the paradoxical functional facilitation of the contralateral M1 via the reduction of interhemispheric inhibition (IHI) between the bilateral M1. This study was double-blind crossover trial. We measured the corticospinal excitability in both M1 and IHI from the left to right M1 by recording motor evoked potentials from first dorsal interosseous muscles using single-pulse and paired-pulse transcranial magnetic stimulation before and after the tSMS intervention for 30 min. We found that the corticospinal excitability of the left M1 decreased, while that of the right M1 increased after tSMS. Moreover, the evaluation of IHI revealed the reduced inhibition from the left to the right M1. Our findings provide new insights on the mechanistic understanding of neuromodulatory effects of tSMS in human.

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Writing's Shadow: Corticospinal Activation during Letter Observation

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_00205 ◽

2012 ◽

Vol 24 (5) ◽

pp. 1138-1148 ◽

Cited By ~ 6

Author(s):

Masahiro Nakatsuka ◽

Mohamed Nasreldin Thabit ◽

Satoko Koganemaru ◽

Ippei Nojima ◽

Hidenao Fukuyama ◽

...

Keyword(s):

Primary Motor Cortex ◽

Motor Evoked Potentials ◽

Short Interval ◽

Single Pulse ◽

Random Order ◽

Intracortical Inhibition ◽

Corticospinal Excitability ◽

Motor Memory ◽

F Wave ◽

The Right

We can recognize handwritten letters despite the variability among writers. One possible strategy is exploiting the motor memory of orthography. By using TMS, we clarified the excitatory and inhibitory neural circuits of the motor corticospinal pathway that might be activated during the observation of handwritten letters. During experiments, participants looked at the handwritten or printed single letter that appeared in a random order. The excitability of the left and right primary motor cortex (M1) was evaluated by motor-evoked potentials elicited by single-pulse TMS. Short interval intracortical inhibition (SICI) of the left M1 was evaluated using paired-pulse TMS. F waves were measured for the right ulnar nerve. We found significant reduction of corticospinal excitability only for the right hand at 300–400 msec after each letter presentation without significant changes in SICI. This suppression is likely to be of supraspinal origin, because of no significant alteration in F-wave amplitudes. These findings suggest that the recognition of handwritten letters may include the implicit knowledge of “writing” in M1. The M1 activation associated with that process, which has been shown in previous neuroimaging studies, is likely to reflect the active suppression of the corticospinal excitability.

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Response inhibition activates distinct motor cortical inhibitory processes

Journal of Neurophysiology ◽

10.1152/jn.00784.2017 ◽

2018 ◽

Vol 119 (3) ◽

pp. 877-886 ◽

Cited By ~ 13

Author(s):

John Cirillo ◽

Matthew J. Cowie ◽

Hayley J. MacDonald ◽

Winston D. Byblow

Keyword(s):

Motor Cortex ◽

Response Inhibition ◽

Primary Motor Cortex ◽

Motor Evoked Potentials ◽

Short Interval ◽

Left Hand ◽

Motor Cortex Excitability ◽

Motor Cortical ◽

Inhibitory Tone ◽

Inhibitory Networks

We routinely cancel preplanned movements that are no longer required. If stopping is forewarned, proactive processes are engaged to selectively decrease motor cortex excitability. However, without advance information there is a nonselective reduction in motor cortical excitability. In this study we examined modulation of human primary motor cortex inhibitory networks during response inhibition tasks with informative and uninformative cues using paired-pulse transcranial magnetic stimulation. Long- (LICI) and short-interval intracortical inhibition (SICI), indicative of GABAB- and GABAA-receptor mediated inhibition, respectively, were examined from motor evoked potentials obtained in task-relevant and task-irrelevant hand muscles when response inhibition was preceded by informative and uninformative cues. When the participants (10 men and 8 women) were cued to stop only a subcomponent of the bimanual response, the remaining response was delayed, and the extent of delay was greatest in the more reactive context, when cues were uninformative. For LICI, inhibition was reduced in both muscles during all types of response inhibition trials compared with the pre-task resting baseline. When cues were uninformative and left-hand responses were suddenly canceled, task-relevant LICI positively correlated with response times of the responding right hand. In trials where left-hand responding was highly probable or known (informative cues), task-relevant SICI was reduced compared with that when cued to rest, revealing a motor set indicative of responding. These novel findings indicate that the GABAB-receptor-mediated pathway may set a default inhibitory tone according to task context, whereas the GABAA-receptor-mediated pathways are recruited proactively with response certainty. NEW & NOTEWORTHY We examined how informative and uninformative cues that trigger both proactive and reactive processes modulate GABAergic inhibitory networks within human primary motor cortex. We show that GABAB inhibition was released during the task regardless of cue type, whereas GABAA inhibition was reduced when responding was highly probable or known compared with rest. GABAB-receptor-mediated inhibition may set a default inhibitory tone, whereas GABAA circuits may be modulated proactively according to response certainty.

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Unravelling the modulation of intracortical inhibition during motor imagery: An adaptive threshold-hunting study

10.1101/846931 ◽

2019 ◽

Author(s):

Cécilia Neige ◽

Dylan Rannaud Monany ◽

Cathy M. Stinear ◽

Winston D. Byblow ◽

Charalambos Papaxanthis ◽

...

Keyword(s):

Transcranial Magnetic Stimulation ◽

Motor Cortex ◽

Motor Imagery ◽

Magnetic Stimulation ◽

Primary Motor Cortex ◽

Short Interval ◽

Intracortical Inhibition ◽

Adaptive Threshold ◽

Mental Simulation ◽

The Right

AbstractMotor imagery (MI) is the mental simulation of an action without any apparent muscular contraction. By means of transcranial magnetic stimulation, few studies revealed a decrease of short-interval intracortical inhibition (SICI) within the primary motor cortex. However, this decrease is ambiguous, as one would expect greater inhibition during MI to prevent overt motor output. The current study investigated the extent of SICI modulation during MI through a methodological and a conceptual reconsideration of i) the importance of parameters to assess SICI (Exp.1) and ii) the inhibitory process within the primary motor cortex as an inherent feature of MI (Exp.2). Participants performed two tasks: 1) rest and 2) imagery of isometric abduction of the right index finger. Using transcranial magnetic stimulation, motor evoked potentials were elicited in the right first dorsal interosseous muscle. An adaptive threshold-hunting paradigm was used, where the stimulus intensity required to maintain a fixed motor evoked potential amplitude was quantified. To test SICI, we conditioned the test stimulus with a conditioning stimulus (CS) of different intensities. Results revealed an Intensity by Task interaction showing that SICI decreased during MI as compared to rest only for the higher CS intensity (Exp.1). At the lowest CS intensities, a Task main effect revealed that SICI increased during MI (Exp.2). SICI modulation during MI depends critically on the CS intensity. By optimising CS intensity, we have shown that SICI circuits may increase during MI, revealing a potential mechanism to prevent the production of a movement while the motor system is activated.HighlightsExcitatory and inhibitory neural processes interact during motor imagery, as the motor regions are activated but no movement is produced.The current study investigated the extent of short interval intracortical inhibition modulation (SICI) during motor imagery.When using optimal settings, SICI increased during motor imagery, likely to prevent the production of an overt movement.

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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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Cortical inhibition, facilitation and plasticity in late-life depression: effects of venlafaxine pharmacotherapy

Journal of Psychiatry and Neuroscience ◽

10.1503/jpn.200001 ◽

2020 ◽

Vol 46 (1) ◽

pp. E88-E96

Author(s):

Jennifer I. Lissemore ◽

Benoit H. Mulsant ◽

Tarek K. Rajji ◽

Jordan F. Karp ◽

Charles F. Reynolds III ◽

...

Keyword(s):

Depressive Symptoms ◽

Motor Cortex ◽

Antidepressant Treatment ◽

Short Interval ◽

Late Life ◽

Cortical Inhibition ◽

Late Life Depression ◽

Paired Pulse ◽

Motor Cortical ◽

Cortical Physiology

Background: Late-life depression is often associated with non-response or relapse following conventional antidepressant treatment. The pathophysiology of late-life depression likely involves a complex interplay between aging and depression, and may include abnormalities in cortical inhibition and plasticity. However, the extent to which these cortical processes are modifiable by antidepressant pharmacotherapy is unknown. Methods: Sixty-eight patients with late-life depression received 12 weeks of treatment with open-label venlafaxine, a serotonin-norepinephrine reuptake inhibitor (≤ 300 mg/d). We combined transcranial magnetic stimulation of the left motor cortex with electromyography recordings from the right hand to measure cortical inhibition using contralateral cortical silent period and paired-pulse short-interval intracortical inhibition paradigms; cortical facilitation using a paired-pulse intracortical facilitation paradigm; and short-term cortical plasticity using a paired associative stimulation paradigm. All measures were collected at baseline, 1 week into treatment (n = 23) and after approximately 12 weeks of treatment. Results: Venlafaxine did not significantly alter cortical inhibition, facilitation or plasticity after 1 or 12 weeks of treatment. Improvements in depressive symptoms during treatment were not associated with changes in cortical physiology. Limitations: The results presented here are specific to the motor cortex. Future work should investigate whether these findings extend to cortical areas more closely associated with depression, such as the dorsolateral prefrontal cortex. Conclusion: These findings suggest that antidepressant treatment with venlafaxine does not exert meaningful changes in motor cortical inhibition or plasticity in late-life depression. The absence of changes in motor cortical physiology, alongside improvements in depressive symptoms, suggests that age-related changes may play a role in previously identified abnormalities in motor cortical processes in late-life depression, and that venlafaxine treatment does not target these abnormalities.

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Modulation of Effects of Intermittent Theta Burst Stimulation Applied Over Primary Motor Cortex (M1) by Conditioning Stimulation of the Opposite M1

Journal of Neurophysiology ◽

10.1152/jn.00274.2009 ◽

2009 ◽

Vol 102 (2) ◽

pp. 766-773 ◽

Cited By ~ 24

Author(s):

Patrick Ragert ◽

Mickael Camus ◽

Yves Vandermeeren ◽

Michael A. Dimyan ◽

Leonardo G. Cohen

Keyword(s):

Transcranial Magnetic Stimulation ◽

Motor Cortex ◽

Magnetic Stimulation ◽

Primary Motor Cortex ◽

Corticospinal Excitability ◽

Homeostatic Plasticity ◽

Theta Burst Stimulation ◽

Burst Stimulation ◽

The Right ◽

Theta Burst

The excitability of the human primary motor cortex (M1) as tested with transcranial magnetic stimulation (TMS) depends on its previous history of neural activity. Homeostatic plasticity might be one important physiological mechanism for the regulation of corticospinal excitability and synaptic plasticity. Although homeostatic plasticity has been demonstrated locally within M1, it is not known whether priming M1 could result in similar homeostatic effects in the homologous M1 of the opposite hemisphere. Here, we sought to determine whether down-regulating excitability (priming) in the right (R) M1 with 1-Hz repetitive transcranial magnetic stimulation (rTMS) changes the excitability-enhancing effect of intermittent theta burst stimulation (iTBS) applied over the homologous left (L) M1. Subjects were randomly allocated to one of four experimental groups in a sham-controlled parallel design with real or sham R M1 1-Hz TMS stimulation always preceding L M1 iTBS or sham by about 10 min. The primary outcome measure was corticospinal excitability in the L M1, as measured by recruitment curves (RCs). Secondary outcome measures included pinch force, simple reaction time, and tapping speed assessed in the right hand. The main finding of this study was that preconditioning R M1 with 1-Hz rTMS significantly decreased the excitability-enhancing effects of subsequent L M1 iTBS on RCs. Application of 1-Hz rTMS over R M1 alone and iTBS over L M1 alone resulted in increased RC in L M1 relative to sham interventions. The present findings are consistent with the hypothesis that homeostatic mechanisms operating across hemispheric boundaries contribute to regulate motor cortical function in the primary motor cortex.

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Reduced Interhemispheric Coherence in Cerebellar Kainic Acid-Induced Lateralized Dystonia

Frontiers in Neurology ◽

10.3389/fneur.2020.580540 ◽

2020 ◽

Vol 11 ◽

Author(s):

Elena Laura Georgescu Margarint ◽

Ioana Antoaneta Georgescu ◽

Carmen Denise Mihaela Zahiu ◽

Stefan-Alexandru Tirlea ◽

Alexandru Rǎzvan Şteopoaie ◽

...

Keyword(s):

Motor Cortex ◽

Kainic Acid ◽

Primary Motor Cortex ◽

Low Frequency ◽

Muscular Activity ◽

Cerebellar Hemisphere ◽

Interhemispheric Coherence ◽

General Locomotor Activity ◽

Complex Circuits ◽

The Right

The execution of voluntary muscular activity is controlled by the primary motor cortex, together with the cerebellum and basal ganglia. The synchronization of neural activity in the intracortical network is crucial for the regulation of movements. In certain motor diseases, such as dystonia, this synchrony can be altered in any node of the cerebello-cortical network. Questions remain about how the cerebellum influences the motor cortex and interhemispheric communication. This research aims to study the interhemispheric cortical communication between the motor cortices during dystonia, a neurological movement syndrome consisting of sustained or repetitive involuntary muscle contractions. We pharmacologically induced lateralized dystonia to adult male albino mice by administering low doses of kainic acid on the left cerebellar hemisphere. Using electrocorticography and electromyography, we investigated the power spectral densities, cortico-muscular, and interhemispheric coherence between the right and left motor cortices, before and during dystonia, for five consecutive days. Mice displayed lateralized abnormal motor signs, a reduced general locomotor activity, and a high score of dystonia. The results showed a progressive interhemispheric coherence decrease in low-frequency bands (delta, theta, beta) during the first 3 days. The cortico-muscular coherence of the affected side had a significant increase in gamma bands on days 3 and 4. In conclusion, lateralized cerebellar dysfunction during dystonia was associated with a loss of connectivity in the motor cortices, suggesting a possible cortical compensation to the initial disturbances induced by cerebellar left hemisphere kainate activation by blocking the propagation of abnormal oscillations to the healthy hemisphere. However, the cerebellum is part of several overly complex circuits, therefore other mechanisms can still be involved in this phenomenon.

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Individualization of tDCS intensity according to corticospinal excitability does not improve stimulation efficacy over the primary motor cortex

Neuroimage: Reports ◽

10.1016/j.ynirp.2021.100028 ◽

2021 ◽

Vol 1 (3) ◽

pp. 100028

Author(s):

Etienne Sallard ◽

Jaimie Lee Rohrbach ◽

Catherine Brandner ◽

Nicolas Place ◽

Jérôme Barral

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Corticospinal Excitability

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