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Efficient and reliable characterization of the corticospinal system using transcranial magnetic stimulation.

ABSTRACT: PURPOSE:The purpose of this study is to develop a method to reliably characterize multiple features of the corticospinal system in a more efficient manner than typically done in transcranial magnetic stimulation studies. METHODS:Forty transcranial magnetic stimulation pulses of varying intensity were given over the first dorsal interosseous motor hot spot in 10 healthy adults. The first dorsal interosseous motor-evoked potential size was recorded during rest and activation to create recruitment curves. The Boltzmann sigmoidal function was fit to the data, and parameters relating to maximal motor-evoked potential size, curve slope, and stimulus intensity leading to half-maximal motor-evoked potential size were computed from the curve fit. RESULTS:Good to excellent test-retest reliability was found for all corticospinal parameters at rest and during activation with 40 transcranial magnetic stimulation pulses. CONCLUSIONS:Through the use of curve fitting, important features of the corticospinal system can be determined with fewer stimuli than typically used for the same information. Determining the recruitment curve provides a basis to understand the state of the corticospinal system and select subject-specific parameters for transcranial magnetic stimulation testing quickly and without unnecessary exposure to magnetic stimulation. This method can be useful in individuals who have difficulty in maintaining stillness, including children and patients with motor disorders.

SUBMITTER: Kukke SN

PROVIDER: S-EPMC4744647 | biostudies-literature | 2014 Jun

REPOSITORIES: biostudies-literature

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Efficient and reliable characterization of the corticospinal system using transcranial magnetic stimulation.

Kukke Sahana N SN Paine Rainer W RW Chao Chi-Chao CC de Campos Ana C AC Hallett Mark M

Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society 20140601 3

<h4>Purpose</h4>The purpose of this study is to develop a method to reliably characterize multiple features of the corticospinal system in a more efficient manner than typically done in transcranial magnetic stimulation studies.<h4>Methods</h4>Forty transcranial magnetic stimulation pulses of varying intensity were given over the first dorsal interosseous motor hot spot in 10 healthy adults. The first dorsal interosseous motor-evoked potential size was recorded during rest and activation to crea ...[more]

PMID: 24887609

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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.

Project description:In preoperative planning for neurosurgery, both anatomical (diffusion imaging tractography) and functional tools (MR-navigated transcranial magnetic stimulation) are increasingly used to identify and preserve eloquent language structures specific to individuals. Using these tools in healthy adults shows that speech production errors occur mainly in perisylvian cortical sites that correspond to subject-specific terminations of the major language pathway, the arcuate fasciculus. It is not clear whether this correspondence remains in oncological patients with altered tissue. We studied a heterogeneous cohort of 30 patients (fourteen male, mean age 44), undergoing a first or second surgery for a left hemisphere brain tumour in a language-eloquent region, to test whether speech production errors induced by preoperative transcranial magnetic stimulation had consistent anatomical correspondence to the arcuate fasciculus. We used navigated repetitive transcranial magnetic stimulation during picture naming and recorded different perisylvian sites where transient interference to speech production occurred. Spherical deconvolution diffusion imaging tractography was performed to map the direct fronto-temporal and indirect (fronto-parietal and parieto-temporal) segments of the arcuate fasciculus in each patient. Speech production errors were reported in all patients when stimulating the frontal lobe, and in over 90% of patients in the parietal lobe. Errors were less frequent in the temporal lobe (54%). In all patients, at least one error site corresponded to a termination of the arcuate fasciculus, particularly in the frontal and parietal lobes, despite distorted anatomy due to a lesion and/or previous resection. Our results indicate that there is strong correspondence between terminations of the arcuate fasciculus and speech errors. This indicates that white matter anatomy may be a robust marker for identifying functionally eloquent cortex, particularly in the frontal and parietal lobe. This knowledge may improve targets for preoperative mapping of language in the neurosurgical setting.

Dataset Information

Efficient and reliable characterization of the corticospinal system using transcranial magnetic stimulation.

Publications

Efficient and reliable characterization of the corticospinal system using transcranial magnetic stimulation.

Similar Datasets

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