Dataset Information

Interindividual Variability of Lower-Limb Motor Cortical Plasticity Induced by Theta Burst Stimulation.

ABSTRACT: Theta burst stimulation (TBS) has been used as a tool to induce synaptic plasticity and improve neurological disorders. However, there is high interindividual variability in the magnitude of the plastic changes observed after TBS, which hinders its clinical applications. The electric field induced by transcranial magnetic stimulation (TMS) is strongly affected by the depth of the stimulated brain region. Therefore, it is possible that the variability in the response to TBS over the lower-limb motor cortex is different for the hand area. This study investigated the variability of TBS-induced synaptic plasticity in the lower-limb motor cortex, for intermittent TBS (iTBS), continuous TBS (cTBS), and sham iTBS, in 48 healthy young participants. The motor cortical and intracortical excitability of the tibialis anterior was tested before and after TBS using TMS. The results showed that iTBS had facilitatory effects on motor cortex excitability and intracortical inhibition, whereas cTBS exerted opposite effects. Twenty-seven percent of individuals exhibited enhanced motor cortical plasticity after iTBS, whereas 63% of participants showed enhanced plasticity after cTBS. In addition, the amount of TBS-induced plasticity was correlated with the intracortical excitability and the variability of the motor evoked potential prior to TBS. Our study demonstrated the high variability of the iTBS-induced lower-limb motor cortical plasticity, which was affected by the sensitivity of intracortical interneuronal circuits. These findings provide further insights into the variation of the response to TBS according to the anatomy of the stimulated brain region and the excitability of the intracortical circuit.

SUBMITTER: Katagiri N

PROVIDER: S-EPMC7691321 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Interindividual Variability of Lower-Limb Motor Cortical Plasticity Induced by Theta Burst Stimulation.

Katagiri Natsuki N Yoshida Shinya S Koseki Tadaki T Kudo Daisuke D Namba Shigehiro S Tanabe Shigeo S Huang Ying-Zu YZ Yamaguchi Tomofumi T

Frontiers in neuroscience 20201113

Theta burst stimulation (TBS) has been used as a tool to induce synaptic plasticity and improve neurological disorders. However, there is high interindividual variability in the magnitude of the plastic changes observed after TBS, which hinders its clinical applications. The electric field induced by transcranial magnetic stimulation (TMS) is strongly affected by the depth of the stimulated brain region. Therefore, it is possible that the variability in the response to TBS over the lower-limb mo ...[more]

PMID: 33281542

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Project description:BackgroundOver the past decade, the number of experimental and clinical studies using theta-burst-stimulation (TBS) protocols of transcranial magnetic stimulation (TMS) to modulate brain activity has risen substantially. The use of TBS is motivated by the assumption that these protocols can reliably and lastingly modulate cortical excitability despite their short duration and low number of stimuli. However, this assumption, and thus the experimental validity of studies using TBS, is challenged by recent work showing large inter- and intra-subject variability in response to TBS protocols.ObjectivesTo date, the reproducibility of TBS effects in humans has been exclusively assessed with motor evoked potentials (MEPs), which provide an indirect and limited measure of cortical excitability. Here we combined TMS with electroencephalography (TMS-EEG) and report the first comprehensive investigation of (1) direct TMS-evoked cortical responses to intermittent (iTBS) and continuous TBS (cTBS) of the human motor cortex, and (2) reproducibility of both iTBS- and cTBS-induced cortical response modulation against a robust sham control across repeat visits with commonly used cortical responsivity metrics.ResultsWe show that although single pulse TMS generates stable and reproducible cortical responses across visits, the modulatory effects of TBS vary substantially both between and within individuals. Overall, at the group level, most measures of the iTBS and cTBS-induced effects were not significantly different from sham-TBS. Most importantly, none of the significant TBS-induced effects observed in visit-1 were reproduced in visit-2.ConclusionsOur findings suggest that the generally accepted mechanisms of TBS-induced neuromodulation, i.e. through changes in cortical excitability, may not be accurate. Future research is needed to determine the mechanisms underlying the established therapeutic effects of TBS in neuropsychiatry and examine reproducibility of TBS-induced neuromodulation through oscillatory response dynamics.

Project description:BackgroundUpper limb dysfunction is one of common sequelae of stroke which limits daily activities and decreases quality of life of patients, as well as increasing caregiving burden on families. Theta burst stimulation (TBS) is considered to be a beneficial therapy for post-stroke patients with upper limb motor dysfunction, but there is a lack of a high quality evidence. We aim to investigate the effectiveness and safety of TBS for upper limb motor dysfunction in patients with stroke.MethodsThe following databases will be searched: PubMed, EMBASE, The Cochrane Library, Web of Science, China Biology Medicine (CBM), China National Knowledge infrastructure (CNKI), Technology Periodical Database (VIP) and WanFang Data from the inception to October 2019. All relevant randomized controlled trials (RCTs) using TBS to treat poststroke patients with upper limb motor dysfunction will be included. The primary outcome is Upper Limb Fugl-Meyer Assessment (UL-FMA). Secondary outcomes will include Action Research Arm Test (ARAT), Box and Block Test (BBT), Wolf Motor Function Test (WMFT), Motor Assessment Scale (MAS), Nine Hole Peg Test (NHPT), Grip strength and other scales evaluating the upper limb motor function. Adverse effects will also be evaluated. Two reviewers will screen studies, extract data and assess the risk of bias of included studies independently. Data analysis will be conducted using Review Manager software (RevMan, version 5.3.5) and R software (version 3.6.1).ResultsOur SR will be conducted according to AMSTAR 2.0 and reported in compliance with PRISMA. The findings of this SR will be disseminated through peer-reviewed publications or conference presentations.ConclusionOur study will provide evidence for the effectiveness and safety of theta burst stimulation for upper limb motor dysfunction in patients with stroke.Ethics and disseminationThis systematic review (SR) does not require formal ethical approval since no privacy health information will be included. The findings of this SR will be disseminated through peer-reviewed publications or conference presentations.Prospero registration numberCRD42019142462.

Dataset Information

Interindividual Variability of Lower-Limb Motor Cortical Plasticity Induced by Theta Burst Stimulation.

Publications

Interindividual Variability of Lower-Limb Motor Cortical Plasticity Induced by Theta Burst Stimulation.

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