Hemispheric Differences in Motor Cortex Excitability During a Simple Index Finger Abduction Task in Humans

Semmler, John G. and Michael A. Nordstrom. Hemispheric differences in motor cortex excitability during a simple index finger abduction task in humans. J. Neurophysiol. 79: 1246–1254, 1998.Transcranial magnetic (TMS) and electrical (TES) stimulation was used to assess the contribution of the corticospinal pathway to activation of the first dorsal interosseous muscle (FDI) in each hand of 16 right-handed subjects. TMS was applied at relaxed threshold intensity while the subject performed isometric index finger abduction at seven force levels [0.5 N to 50% maximal voluntary contraction (MVC)]. In a separate session, TES of equivalent intensity was applied to each hemisphere in 5 of these subjects while they performed the same force-matching protocol. In the resting state, mean threshold intensity for a muscle-evoked potential (MEP) in FDI using TMS was similar for the hemispheres controlling the dominant and nondominant hands. The size of the threshold MEPs in resting FDI after TMS and TES were also similar in each hand. With TMS, contraction-induced facilitation of the MEP in FDI was significantly larger when the nondominant hand was used for index finger abduction. In the pooled data, the nondominant/dominant ratio of MEP areas (normalized to the maximum M wave) ranged from 1.7 in the weakest contraction (0.5 N) to 1.1 in the strongest (50% MVC). Eight subjects had significant differences between hands in favour of the nondominant hand, whereas in two subjects contraction-induced facilitation of MEPs was larger in the dominant hand. In five subjects for whom detailed motor unit data were available from a previous study, lateral differences in MEP facilitation were positively correlated with differences in FDI motor unit synchronization between hands. With TES, contraction-induced facilitation of the MEP was similar in each hand, suggesting that spinal excitability was equivalent on both sides. For the group of five subjects tested with both stimulation techniques, contraction-induced facilitation of the MEP was significantly larger after TMS than that obtained with TES when the contraction was performed with the nondominant hand, but not when the dominant hand was used to perform the task. We conclude that the extent of corticospinal neuron involvement in the command for simple index finger abduction in right-handed subjects is generally greater when the nondominant hand is used, compared with the same task performed with the dominant hand.

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Intermanual Differences in Movement-related Interhemispheric Inhibition

Journal of Cognitive Neuroscience ◽

10.1162/jocn.2007.19.2.204 ◽

2007 ◽

Vol 19 (2) ◽

pp. 204-213 ◽

Cited By ~ 151

Author(s):

Julie Duque ◽

Nagako Murase ◽

Pablo Celnik ◽

Friedhelm Hummel ◽

Michelle Harris-Love ◽

...

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Critical Role ◽

Hand Movements ◽

Dominant Hand ◽

Interhemispheric Inhibition ◽

Movement Onset ◽

Nondominant Hand ◽

Long Time ◽

The Right

Interhemispheric inhibition (IHI) between motor cortical areas is thought to play a critical role in motor control and could influence manual dexterity. The purpose of this study was to investigate IHI preceding movements of the dominant and nondominant hands of healthy volunteers. Movement-related IHI was studied by means of a double-pulse transcranial magnetic stimulation protocol in right-handed individuals in a simple reaction time paradigm. IHI targeting the motor cortex contralateral (IHIc) and ipsilateral (IHIi) to each moving finger was determined. IHIc was comparable after the go signal, a long time preceding movement onset, in both hands. Closer to movement onset, IHIc reversed into facilitation for the right dominant hand but remained inhibitory for left nondominant hand movements. IHIi displayed a nearly constant inhibition with a trough early in the premovement period in both hands. In conclusion, our results unveil a more important modulation of interhemispheric interactions during generation of dominant than nondominant hand movements. This modulation essentially consisted of a shift from a balanced IHI at rest to an IHI predominantly directed toward the ipsilateral primary motor cortex at movement onset. Such a mechanism might release muscles from inhibition in the contralateral primary motor cortex while preventing the occurrence of the mirror activity in ipsilateral primary motor cortex and could therefore contribute to intermanual differences in dexterity.

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Hemispheric differences in motor cortex excitability during training of a novel goal-directed motor task

Brain Stimulation ◽

10.1016/j.brs.2008.06.135 ◽

2008 ◽

Vol 1 (3) ◽

pp. 290

Author(s):

M. Christova ◽

E. Gallasch ◽

D. Rafolt

Keyword(s):

Motor Cortex ◽

Motor Task ◽

Hemispheric Differences ◽

Motor Cortex Excitability

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A BCI-based vibrotactile neurofeedback training improves motor cortical excitability during motor imagery

10.1101/2021.02.28.433220 ◽

2021 ◽

Author(s):

Nikita Grigorev ◽

Andrey Savosenkov ◽

Maksim Lukoyanov ◽

Anna Udoratina ◽

Natalia Shusharina ◽

...

Keyword(s):

Motor Cortex ◽

Motor Imagery ◽

Cortical Excitability ◽

Dominant Hand ◽

Mu Rhythm ◽

Vibrotactile Feedback ◽

Motor Cortical Excitability ◽

Cortex Area ◽

Motor Cortex Excitability ◽

Motor Cortical

In this study, we address the issue of whether vibrotactile feedback can enhance the motor cortex excitability translated into the plastic changes in local cortical areas during motor imagery (MI) BCI-based training. For this purpose, we focused on two of the most notable neurophysiological effects of MI - the event-related-desynchronization (ERD) level and the increase in cortical excitability assessed with navigated transcranial magnetic stimulation (nTMS). For TMS navigation, we used individual high-resolution 3D brain MRIs. Ten BCI-naive and healthy adults participated in this study. The MI (rest or left/right hand imagery using Graz-BCI paradigm) tasks were performed separately in the presence and absence of feedback. To investigate how much the presence/absence of vibrotactile feedback in MI BCI-based training could contribute to the sensorimotor cortical activations, we compared the MEPs amplitude during MI after training with and without feedback. In addition, the ERD levels during MI BCI-based training were investigated. Our findings provide evidence that applying vibrotactile feedback during MI training leads to (i) an enhancement of the desynchronization level of mu-rhythm EEG patterns over the contralateral motor cortex area corresponding to the MI of the non-dominant hand; (ii) an increase in motor cortical excitability in hand muscle representation corresponding to a muscle engaged by the MI.

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Proprioceptive Accuracy in Two Dimensions

Perceptual and Motor Skills ◽

10.2466/pms.1987.64.3.831 ◽

1987 ◽

Vol 64 (3) ◽

pp. 831-846 ◽

Cited By ~ 38

Author(s):

Alan Crowe ◽

Wim Keessen ◽

Wim Kuus ◽

Ronald Van Vliet ◽

Andre Zegeling

Keyword(s):

Visual Cues ◽

Index Finger ◽

Arm Movements ◽

Target Position ◽

Two Dimensions ◽

Dominant Hand ◽

Left Hand ◽

Nondominant Hand ◽

Right Hand ◽

The Right

Slow arm movements were made over a smooth horizontal table at shoulder height. With visual cues excluded, target position was indicated by the index finger of the nonmoving arm touching the underside of the table. 11 students (mean age 21.9 yr.) and 24 children (mean age 10.3 yr.) were compared. Both groups showed an ‘overlap effect’: movements with the right hand went too far to the left, while movements with the left hand went too far to the right. The children as a group were significantly less accurate than the students and showed a significant asymmetry in that movements with the dominant hand were more accurate than those with the nondominant hand.

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'Direct' and 'crossed' modulation of human motor cortex excitability following exercise

Neuroscience Letters ◽

10.1016/s0304-3940(96)13010-x ◽

1996 ◽

Vol 216 (2) ◽

pp. 97-100 ◽

Cited By ~ 1

Author(s):

C Bonato

Keyword(s):

Motor Cortex ◽

Human Motor Cortex ◽

Motor Cortex Excitability ◽

Human Motor

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Increase in motor-cortex excitability after constraint-induced movement therapy in patients with congenital stroke

Klinische Neurophysiologie ◽

10.1055/s-2006-939319 ◽

2006 ◽

Vol 37 (01) ◽

Author(s):

M Walther ◽

V Brodbeck ◽

H Jünger ◽

M Staudt ◽

...

Keyword(s):

Motor Cortex ◽

Movement Therapy ◽

Constraint Induced Movement Therapy ◽

Motor Cortex Excitability

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Screwdriver torque strength and physiological cost of muscles dependent on hand preference and direction of rotation

Occupational Ergonomics ◽

10.3233/oer-1998-1103 ◽

1998 ◽

Vol 1 (1) ◽

pp. 13-22

Author(s):

Helmut Strasser ◽

Baoquiu Wang

Keyword(s):

Hand Preference ◽

Dominant Hand ◽

Muscle Forces ◽

Maximum Torque ◽

Physiological Cost ◽

Nondominant Hand ◽

Physiological Differences ◽

Torque Values ◽

The Right

The focus of this research was to investigate how maximum torque and muscle forces were affected by pronation and supination, i.e., inward and outward rotation of the forearm in a series of screwdriver tests with 6 varied handles. Consecutively, maximum torque for pronation and supination was determined, submaximum isometric levels of torque were demanded, and, finally, an equal dynamic screwing work for all subjects was simulated. Physiological cost of performance was simultaneously measured by registrations of electromyographic activities (EA) from 4 muscles, which were expected to be involved intensively in screwing tasks. Significant and essential differences between maximum torque values produced by pronation and supination of the right and the left arm of the mainly right-handed subjects were found. For clockwise work, as it is necessary e.g., for driving in screws, inward rotations (pronations) of the nondominant hand are at least as strong as outward rotations of the dominant hand. Differences of about 8% favour of pronations were found. Yet, for counter clockwise work involved e.g., in removing a tightened screw, inward rotations of the dominant hand yielded a much more stronger torque strength than outward rotations of the nondominant hand. Differences of more than 50% right-handed subjects were measured. Also, EA values of the 4 muscles monitored on the right arm differed significantly. Systematically operational and physiological differences due to the varied screwdriver grips, as results of investigations which were not the main objective of the study, corresponded well with the findings of prior studies.

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Effect of opposing needling on motor cortex excitability in healthy participants and in patients with post-stroke hemiplegia: study protocol for a single-blind, randomised controlled trial

Trials ◽

10.1186/s13063-021-05443-x ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Mindong Xu ◽

Yinyu Zi ◽

Jianlu Wu ◽

Nenggui Xu ◽

Liming Lu ◽

...

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Motor Evoked Potentials ◽

Controlled Trial ◽

Secondary Outcome ◽

Post Stroke ◽

Motor Cortex Excitability ◽

Opposing Needling ◽

Single Blind ◽

Healthy Participants

Abstract Background Opposing needling has an obvious curative effect in the treatment of post-stroke hemiplegia; however, the mechanism of the opposing needling in the treatment of post-stroke hemiplegia is still not clear. The purpose of this study is to investigate the effect of opposing needling on the excitability of primary motor cortex (M1) of healthy participants and patients with post-stroke hemiplegia, which may provide insight into the mechanisms of opposing needling in treating post-stroke hemiplegia. Methods This will be a single-blind, randomised, sham-controlled trial in which 80 healthy participants and 40 patients with post-stroke hemiplegia will be recruited. Healthy participants will be randomised 1:1:1:1 to the 2-Hz, 50-Hz, 100-Hz, and sham electroacupuncture groups. Patients with post-stroke hemiplegia will be randomised 1:1 to the opposing needling or conventional treatment groups. The M1 will be located in all groups by using neuroimaging-based navigation. The stimulator coil of transcranial magnetic stimulation (TMS) will be moved over the left and right M1 in order to identify the TMS hotspot, followed by a recording of resting motor thresholds (RMTs) and motor-evoked potentials (MEPs) of the thenar muscles induced by TMS before and after the intervention. The primary outcome measure will be the percent change in the RMTs of the thenar muscles at baseline and after the intervention. The secondary outcome measures will be the amplitude (μV) and latency (ms) of the MEPs of the thenar muscles at baseline and after the intervention. Discussion The aim of this trial is to explore the effect of opposing needling on the excitability of M1 of healthy participants and patients with post-stroke hemiplegia. Trial registration Chinese Clinical Trial Registry ChiCTR1900028138. Registered on 13 December 2019.

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Transcranial Magnetic Stimulation as a Tool to Investigate Motor Cortex Excitability in Sport

Brain Sciences ◽

10.3390/brainsci11040432 ◽

2021 ◽

Vol 11 (4) ◽

pp. 432

Author(s):

Fiorenzo Moscatelli ◽

Antonietta Messina ◽

Anna Valenzano ◽

Vincenzo Monda ◽

Monica Salerno ◽

...

Keyword(s):

Transcranial Magnetic Stimulation ◽

Motor Cortex ◽

Magnetic Stimulation ◽

Motor Coordination ◽

Cortical Excitability ◽

Non Invasive ◽

Motor Cortex Excitability ◽

Invasive Method ◽

And Control ◽

The Impact

Transcranial magnetic stimulation, since its introduction in 1985, has brought important innovations to the study of cortical excitability as it is a non-invasive method and, therefore, can be used both in healthy and sick subjects. Since the introduction of this cortical stimulation technique, it has been possible to deepen the neurophysiological aspects of motor activation and control. In this narrative review, we want to provide a brief overview regarding TMS as a tool to investigate changes in cortex excitability in athletes and highlight how this tool can be used to investigate the acute and chronic responses of the motor cortex in sport science. The parameters that could be used for the evaluation of cortical excitability and the relative relationship with motor coordination and muscle fatigue, will be also analyzed. Repetitive physical training is generally considered as a principal strategy for acquiring a motor skill, and this process can elicit cortical motor representational changes referred to as use-dependent plasticity. In training settings, physical practice combined with the observation of target movements can enhance cortical excitability and facilitate the process of learning. The data to date suggest that TMS is a valid technique to investigate the changes in motor cortex excitability in trained and untrained subjects. Recently, interest in the possible ergogenic effect of non-invasive brain stimulation in sport is growing and therefore in the future it could be useful to conduct new experiments to evaluate the impact on learning and motor performance of these techniques.

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