scholarly journals Distributed cortical structural properties contribute to motor cortical excitability and inhibition

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.

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

2013 ◽  
Vol 110 (5) ◽  
pp. 1158-1166 ◽  
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.

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

2021 ◽  
Vol 11 (1) ◽  
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.

scholarly journals Writing's Shadow: Corticospinal Activation during Letter Observation

2012 ◽  
Vol 24 (5) ◽  
pp. 1138-1148 ◽  
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.

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

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5588 ◽  
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.

BDNF polymorphism and inter hemispheric balance of motor cortex excitability: a preliminary study

2021 ◽  
Author(s):  
Raffaele Dubbioso ◽  
Giovanni Pellegrino ◽  
Federico Ranieri ◽  
Giovanni Di Pino ◽  
Fioravante Capone ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Short Interval ◽  
Intracortical Inhibition ◽  
Val66met Polymorphism ◽  
Healthy Humans ◽  
Motor Cortex Excitability ◽  
Active Motor ◽  
Bdnf Val66met Polymorphism

Preclinical studies have demonstrated that Brain-Derived Neurotrophic Factor (BDNF) plays a crucial role in the homeostatic regulation of cortical excitability and excitation/inhibition balance. Using transcranial magnetic stimulation (TMS) techniques we investigated whether BDNF polymorphism could influence cortical excitability of the left and right primary motor cortex in healthy humans. Twenty-nine participants were recruited and genotyped for the presence of the BDNF Val66Met polymorphism, namely homozygous for the valine allele (Val/Val), heterozygotes (Val/Met), and homozygous for the methionine allele (Met/Met). Blinded to the latter, we evaluated inhibitory and facilitatory circuits of the left (LH) and right motor cortex (RH) by measuring resting (RMT) and active motor threshold (AMT), short interval intracortical inhibition (SICI) and intracortical facilitation (ICF). For each neurophysiological metric we also considered the inter-hemispheric balance expressed by the Laterality Index (LI). Val/Val participants (n= 21) exhibited an overall higher excitability of the LH compared to the RH, as probed by lower motor thresholds, lower SICI and higher ICF. Val/Val participants displayed positive LI, especially for AMT and ICF (all p< 0.05), indicating higher LH excitability and more pronounced inter-hemispheric excitability imbalance as compared to Met carriers. Our preliminary results suggest that BDNF Val66Met polymorphism might influence interhemispheric balance of motor cortex excitability.

scholarly journals Cerebellar rTMS and PAS effectively induce cerebellar plasticity

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Martje G. Pauly ◽  
Annika Steinmeier ◽  
Christina Bolte ◽  
Feline Hamami ◽  
Elinor Tzvi ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Healthy Subjects ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Premotor Cortex ◽  
Motor Pathways ◽  
Non Invasive ◽  
Cerebellar Plasticity

AbstractNon-invasive brain stimulation techniques including repetitive transcranial magnetic stimulation (rTMS), continuous theta-burst stimulation (cTBS), paired associative stimulation (PAS), and transcranial direct current stimulation (tDCS) have been applied over the cerebellum to induce plasticity and gain insights into the interaction of the cerebellum with neo-cortical structures including the motor cortex. We compared the effects of 1 Hz rTMS, cTBS, PAS and tDCS given over the cerebellum on motor cortical excitability and interactions between the cerebellum and dorsal premotor cortex / primary motor cortex in two within subject designs in healthy controls. In experiment 1, rTMS, cTBS, PAS, and tDCS were applied over the cerebellum in 20 healthy subjects. In experiment 2, rTMS and PAS were compared to sham conditions in another group of 20 healthy subjects. In experiment 1, PAS reduced cortical excitability determined by motor evoked potentials (MEP) amplitudes, whereas rTMS increased motor thresholds and facilitated dorsal premotor-motor and cerebellum-motor cortex interactions. TDCS and cTBS had no significant effects. In experiment 2, MEP amplitudes increased after rTMS and motor thresholds following PAS. Analysis of all participants who received rTMS and PAS showed that MEP amplitudes were reduced after PAS and increased following rTMS. rTMS also caused facilitation of dorsal premotor-motor cortex and cerebellum-motor cortex interactions. In summary, cerebellar 1 Hz rTMS and PAS can effectively induce plasticity in cerebello-(premotor)-motor pathways provided larger samples are studied.

scholarly journals Online and offline effects of transcranial alternating current stimulation of the primary motor cortex

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ivan Pozdniakov ◽  
Alicia Nunez Vorobiova ◽  
Giulia Galli ◽  
Simone Rossi ◽  
Matteo Feurra
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Random Noise ◽  
Single Pulse ◽  
Alternating Current ◽  
Online Application ◽  
Transcranial Random Noise Stimulation ◽  
Transcranial Alternating Current Stimulation

AbstractTranscranial alternating current stimulation (tACS) is a non-invasive brain stimulation technique that allows interaction with endogenous cortical oscillatory rhythms by means of external sinusoidal potentials. The physiological mechanisms underlying tACS effects are still under debate. Whereas online (e.g., ongoing) tACS over the motor cortex induces robust state-, phase- and frequency-dependent effects on cortical excitability, the offline effects (i.e. after-effects) of tACS are less clear. Here, we explored online and offline effects of tACS in two single-blind, sham-controlled experiments. In both experiments we used neuronavigated transcranial magnetic stimulation (TMS) of the primary motor cortex (M1) as a probe to index changes of cortical excitability and delivered M1 tACS at 10 Hz (alpha), 20 Hz (beta) and sham (30 s of low-frequency transcranial random noise stimulation; tRNS). Corticospinal excitability was measured by single pulse TMS-induced motor evoked potentials (MEPs). tACS was delivered online in Experiment 1 and offline in Experiment 2. In Experiment 1, the increase of MEPs size was maximal with the 20 Hz stimulation, however in Experiment 2 neither the 10 Hz nor the 20 Hz stimulation induced tACS offline effects. These findings support the idea that tACS affects cortical excitability only during online application, at least when delivered on the scalp overlying M1, thereby contributing to the development of effective protocols that can be applied to clinical populations.

Intracortical Inhibition During Volitional Inhibition of Prepared Action

2006 ◽  
Vol 95 (6) ◽  
pp. 3371-3383 ◽  
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.

scholarly journals Expanding the parameter space of anodal transcranial direct current stimulation of the primary motor cortex

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Desmond Agboada ◽  
Mohsen Mosayebi Samani ◽  
Asif Jamil ◽  
Min-Fang Kuo ◽  
Michael A. Nitsche
Keyword(s):  
Motor Cortex ◽  
Parameter Space ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Anodal Tdcs ◽  
Stimulation Parameters ◽  
Motor Cortex Excitability ◽  
The Impact ◽  
Motor Cortex Plasticity

AbstractSize and duration of the neuroplastic effects of tDCS depend on stimulation parameters, including stimulation duration and intensity of current. The impact of stimulation parameters on physiological effects is partially non-linear. To improve the utility of this intervention, it is critical to gather information about the impact of stimulation duration and intensity on neuroplasticity, while expanding the parameter space to improve efficacy. Anodal tDCS of 1–3 mA current intensity was applied for 15–30 minutes to study motor cortex plasticity. Sixteen healthy right-handed non-smoking volunteers participated in 10 sessions (intensity-duration pairs) of stimulation in a randomized cross-over design. Transcranial magnetic stimulation (TMS)-induced motor-evoked potentials (MEP) were recorded as outcome measures of tDCS effects until next evening after tDCS. All active stimulation conditions enhanced motor cortex excitability within the first 2 hours after stimulation. We observed no significant differences between the three stimulation intensities and durations on cortical excitability. A trend for larger cortical excitability enhancements was however observed for higher current intensities (1 vs 3 mA). These results add information about intensified tDCS protocols and suggest that the impact of anodal tDCS on neuroplasticity is relatively robust with respect to gradual alterations of stimulation intensity, and duration.

Time Course of Determination of Movement Direction in the Reaction Time Task in Humans

2001 ◽  
Vol 86 (3) ◽  
pp. 1195-1201 ◽  
Author(s):  
Martin Sommer ◽  
Joseph Classen ◽  
Leonardo G. Cohen ◽  
Mark Hallett
Keyword(s):  
Reaction Time ◽  
Motor Cortex ◽  
Time Course ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Movement Direction ◽  
Movement Onset ◽  
Thumb Movement

The primary motor cortex produces motor commands that include encoding the direction of movement. Excitability of the motor cortex in the reaction time (RT) task can be assessed using transcranial magnetic stimulation (TMS). To elucidate the timing of the increase in cortical excitability and of the determination of movement direction before movement onset, we asked six right-handed, healthy subjects to either abduct or extend their right thumb after a go-signal indicated the appropriate direction. Between the go-signal and movement onset, single TMS pulses were delivered to the contralateral motor cortex. We recorded the direction of the TMS-induced thumb movement and the amplitude of motor-evoked potentials (MEPs) from the abductor pollicis brevis and extensor pollicis brevis muscles. Facilitation of MEPs from the prime mover, as early as 200 ms before the end of the reaction time, preceded facilitation of MEPs from the nonprime mover, and both preceded measurable directional change. Compared with a control condition in which no voluntary movement was required, the direction of the TMS-induced thumb movement started to change in the direction of the intended movement as early as 90 ms before the end of the RT, and maximum changes were seen shortly before the end of reaction time. Movement acceleration also increased with maxima shortly before the end of the RT. We conclude that in concentric movements a change of the movement direction encoded in the primary motor cortex occurs in the 200 ms prior to movement onset, which is as early as increased excitability itself can be detected.

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