Dataset Information

Real-time changes in corticospinal excitability during voluntary contraction with concurrent electrical stimulation.

ABSTRACT: While previous studies have assessed changes in corticospinal excitability following voluntary contraction coupled with electrical stimulation (ES), we sought to examine, for the first time in the field, real-time changes in corticospinal excitability. We monitored motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation and recorded the MEPs using a mechanomyogram, which is less susceptible to electrical artifacts. We assessed the MEPs at each level of muscle contraction of wrist flexion (0%, 5%, or 20% of maximum voluntary contraction) during voluntary wrist flexion (flexor carpi radialis (FCR) voluntary contraction), either with or without simultaneous low-frequency (10 Hz) ES of the median nerve that innervates the FCR. The stimulus intensity corresponded to 1.2 × perception threshold. In the FCR, voluntary contraction with median nerve stimulation significantly increased corticospinal excitability compared with FCR voluntary contraction without median nerve stimulation (p<0.01). In addition, corticospinal excitability was significantly modulated by the level of FCR voluntary contraction. In contrast, in the extensor carpi radialis (ECR), FCR voluntary contraction with median nerve stimulation significantly decreased corticospinal excitability compared with FCR voluntary contraction without median nerve stimulation (p<0.05). Thus, median nerve stimulation during FCR voluntary contraction induces reciprocal changes in cortical excitability in agonist and antagonist muscles. Finally we also showed that even mental imagery of FCR voluntary contraction with median nerve stimulation induced the same reciprocal changes in cortical excitability in agonist and antagonist muscles. Our results support the use of voluntary contraction coupled with ES in neurorehabilitation therapy for patients.

SUBMITTER: Yamaguchi T

PROVIDER: S-EPMC3458815 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Real-time changes in corticospinal excitability during voluntary contraction with concurrent electrical stimulation.

Yamaguchi Tomofumi T Sugawara Kenichi K Tanaka Satoshi S Yoshida Naoshin N Saito Kei K Tanabe Shigeo S Muraoka Yoshihiro Y Liu Meigen M

PloS one 20120926 9

While previous studies have assessed changes in corticospinal excitability following voluntary contraction coupled with electrical stimulation (ES), we sought to examine, for the first time in the field, real-time changes in corticospinal excitability. We monitored motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation and recorded the MEPs using a mechanomyogram, which is less susceptible to electrical artifacts. We assessed the MEPs at each level of muscle contraction of ...[more]

PMID: 23049955

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Project description:The magnitude and direction of reported physiological effects induced using transcranial magnetic stimulation (TMS) to modulate human motor cortical excitability have proven difficult to replicate routinely. We conducted an online survey on the prevalence and possible causes of these reproducibility issues. A total of 153 researchers were identified via their publications and invited to complete an anonymous internet-based survey that asked about their experience trying to reproduce published findings for various TMS protocols. The prevalence of questionable research practices known to contribute to low reproducibility was also determined. We received 47 completed surveys from researchers with an average of 16.4 published papers (95% CI 10.8-22.0) that used TMS to modulate motor cortical excitability. Respondents also had a mean of 4.0 (2.5-5.7) relevant completed studies that would never be published. Across a range of TMS protocols, 45-60% of respondents found similar results to those in the original publications; the other respondents were able to reproduce the original effects only sometimes or not at all. Only 20% of respondents used formal power calculations to determine study sample sizes. Others relied on previously published studies (25%), personal experience (24%) or flexible post-hoc criteria (41%). Approximately 44% of respondents knew researchers who engaged in questionable research practices (range 30–81%), yet only 18% admitted to engaging in them (range 6–38%) [corrected]. These practices included screening subjects to find those that respond in a desired way to a TMS protocol, selectively reporting results and rejecting data based on a gut feeling. In a sample of 56 published papers that were inspected, not a single questionable research practice was reported. Our survey revealed that approximately 50% of researchers are unable to reproduce published TMS effects. Researchers need to start increasing study sample size and eliminating--or at least reporting--questionable research practices in order to make the outcomes of TMS research reproducible.

Dataset Information

Real-time changes in corticospinal excitability during voluntary contraction with concurrent electrical stimulation.

Publications

Real-time changes in corticospinal excitability during voluntary contraction with concurrent electrical stimulation.

Similar Datasets

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