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

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

Journal of Neurophysiology ◽

10.1152/jn.00686.2014 ◽

2015 ◽

Vol 113 (7) ◽

pp. 2262-2270 ◽

Cited By ~ 12

Author(s):

Tjerk Zult ◽

Stuart Goodall ◽

Kevin Thomas ◽

Tibor Hortobágyi ◽

Glyn Howatson

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Short Interval ◽

Mirror Image ◽

Corticospinal Excitability ◽

Cortical Inhibition ◽

Electromyographic Activity ◽

Wrist Flexion ◽

Motor Cortical ◽

The Right

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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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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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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NMDA Receptor-Mediated Motor Cortex Plasticity After 20 Hz Transcranial Alternating Current Stimulation

Cerebral Cortex ◽

10.1093/cercor/bhy160 ◽

2018 ◽

Vol 29 (7) ◽

pp. 2924-2931 ◽

Cited By ~ 26

Author(s):

M Wischnewski ◽

M Engelhardt ◽

M A Salehinejad ◽

D J L G Schutter ◽

M -F Kuo ◽

...

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Cortical Excitability ◽

Alternating Current ◽

Beta Oscillations ◽

Human Motor Cortex ◽

After Effects ◽

Transcranial Alternating Current Stimulation ◽

Human Motor ◽

Motor Cortex Plasticity

Abstract Transcranial alternating current stimulation (tACS) has been shown to modulate neural oscillations and excitability levels in the primary motor cortex (M1). These effects can last for more than an hour and an involvement of N-methyl-d-aspartate receptor (NMDAR) mediated synaptic plasticity has been suggested. However, to date the cortical mechanisms underlying tACS after-effects have not been explored. Here, we applied 20 Hz beta tACS to M1 while participants received either the NMDAR antagonist dextromethorphan or a placebo and the effects on cortical beta oscillations and excitability were explored. When a placebo medication was administered, beta tACS was found to increase cortical excitability and beta oscillations for at least 60 min, whereas when dextromethorphan was administered, these effects were completely abolished. These results provide the first direct evidence that tACS can induce NMDAR-mediated plasticity in the motor cortex, which contributes to our understanding of tACS-induced influences on human motor cortex physiology.

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Cutaneous Inputs Can Activate the Ipsilateral Primary Motor Cortex During Bimanual Sensory-Driven Movements in Humans

Journal of Neurophysiology ◽

10.1152/jn.00937.2003 ◽

2004 ◽

Vol 92 (6) ◽

pp. 3200-3209 ◽

Cited By ~ 7

Author(s):

Satoshi Shibuya ◽

Yukari Ohki

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Cortical Excitability ◽

Human Subjects ◽

Random Sequence ◽

Virtual Object ◽

Active Motor ◽

Finger Forces ◽

The Right ◽

Transient Force

Using transcranial magnetic stimulation (TMS), we examined whether sensory input from a finger affects activity of the ipsilateral primary motor cortex (M1) when human subjects hold a virtual object bimanually and whether this ipsilateral activation varies under different contexts. Subjects used both index fingers to hold two plates, which were subjected to unpredictable pulling loads from torque motors. Loads were delivered in a random sequence to either plate or concurrently to both, although the latter occurred most frequently. Finger forces vertical to the plates and surface electromyographs from the first dorsal interosseous muscles were recorded bilaterally during the task. TMS was sometimes applied over the finger area of the left M1 at variable times relative to load onset to examine cortical excitability. Strength of TMS was set around the active motor threshold of the right finger muscle while subjects waited for loading to the handheld plates. When one plate was singly loaded, the M1 contralateral to the loaded finger was activated, causing automatic force increases in the finger. In addition, the ipsilateral M1 was activated during such loading, associated with transient force increases in the contralateral nonloaded finger. Activations in the ipsilateral M1 were also observed during concurrent loading, when activations were stronger than those following single loading of the contralateral plate. Ipsilateral activations weakened when concurrent loading was less frequent. These results suggest interactions between bilateral sensorimotor cortices during bimanual coordinated movements, with strength varying by context.

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Event-related desynchronization reflects downregulation of intracortical inhibition in human primary motor cortex

Journal of Neurophysiology ◽

10.1152/jn.01092.2012 ◽

2013 ◽

Vol 110 (5) ◽

pp. 1158-1166 ◽

Cited By ~ 108

Author(s):

Mitsuaki Takemi ◽

Yoshihisa Masakado ◽

Meigen Liu ◽

Junichi Ushiba

Keyword(s):

Motor Cortex ◽

Motor Imagery ◽

Sensorimotor Cortex ◽

Primary Motor Cortex ◽

Motor Evoked Potentials ◽

Short Interval ◽

Hand Movement ◽

Intracortical Inhibition ◽

Imagery Task ◽

Event Related Desynchronization

There is increasing interest in electroencephalogram (EEG)-based brain-computer interface (BCI) as a tool for rehabilitation of upper limb motor functions in hemiplegic stroke patients. This type of BCI often exploits mu and beta oscillations in EEG recorded over the sensorimotor areas, and their event-related desynchronization (ERD) following motor imagery is believed to represent increased sensorimotor cortex excitability. However, it remains unclear whether the sensorimotor cortex excitability is actually correlated with ERD. Thus we assessed the association of ERD with primary motor cortex (M1) excitability during motor imagery of right wrist movement. M1 excitability was tested by motor evoked potentials (MEPs), short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF) with transcranial magnetic stimulation (TMS). Twenty healthy participants were recruited. The participants performed 7 s of rest followed by 5 s of motor imagery and received online visual feedback of the ERD magnitude of the contralateral hand M1 while performing the motor imagery task. TMS was applied to the right hand M1 when ERD exceeded predetermined thresholds during motor imagery. MEP amplitudes, SICI, and ICF were recorded from the agonist muscle of the imagined hand movement. Results showed that the large ERD during wrist motor imagery was associated with significantly increased MEP amplitudes and reduced SICI but no significant changes in ICF. Thus ERD magnitude during wrist motor imagery represents M1 excitability. This study provides electrophysiological evidence that a motor imagery task involving ERD may induce changes in corticospinal excitability similar to changes accompanying actual movements.

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Inducing Homeostatic-Like Plasticity in Human Motor Cortex Through Converging Corticocortical Inputs

Journal of Neurophysiology ◽

10.1152/jn.91046.2008 ◽

2009 ◽

Vol 102 (6) ◽

pp. 3180-3190 ◽

Cited By ~ 40

Author(s):

Monika Pötter-Nerger ◽

Sarah Fischer ◽

Claudia Mastroeni ◽

Sergiu Groppa ◽

Günther Deuschl ◽

...

Keyword(s):

Motor Cortex ◽

Median Nerve ◽

Primary Motor Cortex ◽

Premotor Cortex ◽

Long Term Potentiation ◽

Corticospinal Excitability ◽

Human Motor Cortex ◽

Induced Changes ◽

Homeostatic Response

Transcranial stimulation techniques have revealed homeostatic-like metaplasticity in the hand area of the human primary motor cortex (M1HAND) that controls stimulation-induced changes in corticospinal excitability. Here we combined two interventional protocols that induce long-term depression (LTD)–like or long-term potentiation (LTP)–like plasticity in left M1HAND through different afferents. We hypothesized that the left M1HAND would integrate LTP- and LTD-like plasticity in a homeostatic fashion. In ten healthy volunteers, low-intensity repetitive transcranial magnetic stimulation (rTMS) of the left dorsal premotor cortex (PMD) was first applied to produce an LTP-like increase (5 Hz rTMS) or LTD-like decrease (1 Hz rTMS) in corticospinal excitability in left M1HAND via premotor-to-motor inputs. Following PMD rTMS, paired-associative stimulation (PAS) was applied to the right median nerve and left M1HAND to induce spike-time–dependent plasticity in sensory-to-motor inputs to left M1HAND. We adjusted the interstimulus interval to the N20 latency of the median nerve somatosensory-evoked cortical potential to produce an LTP-like increase (PASN20+2ms) or an LTD-like decrease (PASN20−5ms) in corticospinal excitability. The amplitude of motor-evoked potentials was recorded from intrinsic hand muscles to assess stimulation-induced changes in corticospinal excitability. Premotor-to-motor preconditioning triggered a homeostatic response to subsequent sensory-to-motor PAS. After facilitatory 5 Hz rTMS, “facilitatory” PASN20+2ms suppressed corticospinal excitability. Likewise, “inhibitory” PASN20−5ms facilitated corticospinal excitability after “inhibitory” 1 Hz rTMS. There was a negative linear relationship between the excitability changes induced by PMD rTMS and those elicited by subsequent PAS. Excitability changes were not paralleled by changes in performance during a finger-tapping task. These results provide evidence for a homeostatic response pattern in the human M1HAND that integrates acute plastic changes evoked through different “input channels.”

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Modulation of Associative Human Motor Cortical Plasticity by Attention

Journal of Neurophysiology ◽

10.1152/jn.00383.2003 ◽

2004 ◽

Vol 92 (1) ◽

pp. 66-72 ◽

Cited By ~ 307

Author(s):

Katja Stefan ◽

Matthias Wycislo ◽

Joseph Classen

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Cognitive Task ◽

Silent Period ◽

Abductor Pollicis Brevis ◽

Human Motor Cortex ◽

Target Hand ◽

Human Motor ◽

The Subject ◽

The Right

The role of attention in generating motor memories remains controversial principally because it is difficult to separate the effects of attention from changes in kinematics of motor performance. We attempted to disentangle attention from performance effects by varying attention while plasticity was induced in human primary motor cortex by external stimulation in the absence of voluntary movement. A paired associative stimulation (PAS) protocol was employed consisting of repetitive application of single afferent electric stimuli, delivered to the right median nerve, paired with single-pulse transcranial magnetic stimulation (TMS) over the optimal site for activation of the right abductor pollicis brevis muscle (APB) to generate near-synchronous events in the left primary motor cortex. In experiment 1, the spatial location of attention was varied. PAS failed to induce plasticity when the subject's attention was directed to their left hand, away from the right target hand the cortical representation of which was being stimulated by PAS. In experiment 2, the grade of attention to the target hand was manipulated. PAS-induced plasticity was maximal when the subject viewed their target hand, and its magnitude was slightly reduced when the subject could only feel their hand. Conversely, plasticity was completely blocked when the subject's attention was diverted from the target hand by a competing cognitive task. A similar modulation by attention was observed for PAS-induced changes in the duration of the silent period evoked by TMS in voluntarily contracted muscle. Associative plasticity in the human motor cortex depends decisively on attention.

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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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