A carregar...
Publicação
Assessing Primary Motor Cortex Excitability and Excitability Modulation by Pairing Transcranial Magnetic Stimulation with Electromyography
| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 640.26 KB | Adobe PDF |
Orientador(es)
Resumo(s)
We describe a protocol to assess motor cortex excitability and its modulation, through paired use of electromyography (EMG) and repetitive transcranial magnetic stimulation (TMS) of the primary motor cortex (M1). EMG recordings use a custom-built system, and surface electrodes are placed over the right first dorsal interosseous (FDI) muscle, with a ground electrode on the left elbow. TMS is performed using a magnetic stimulator with a figure-eight coil, guided by a neuronavigation System. The motor hotspot for the FDI is identified by systematically applying single TMS pulses while adjusting coil placement, and is used as the target for all TMS procedures. The resting motor threshold (rMT) is defined as the minimum intensity required to elicit motor evoked potentials (MEPs) ≥ 50 µV in the EMG recording, in at least 5 out of 10 trials, while the active motor threshold (aMT) is the minimum intensity needed to evoke MEPs ≥ 200 µV in at least 5 out of 10 pulses while the participant maintains 10-20% of their maximal voluntary muscle activation. Baseline cortical excitability is defined as the mean MEP amplitude obtained from 40 single TMS pulses applied at 120% rMT, with pulses delivered at random intervals (6-10 s). Motor cortex excitability modulation is achieved using an intermittent theta-burst stimulation (iTBS) protocol (50 Hz pulse triplets, 80% aMT, 5 Hz for 2 s on/8 s off, repeated 20 times; 600 pulses total). Excitability modulation is assessed through repetition of MEP amplitude measurements at four post-stimulation time points: immediate (T0), 10 min (T10), 20 min (T20), and 30 min (T30). This protocol ensures precise and reproducible assessment of motor cortex excitability and captures the peak of the modulatory effects resulting from iTBS.
Descrição
Funding Information: AJO-M is recipient of a grant from Schuhfried GmBH for norming and validation of cognitive tests, and was national coordinator for Portugal of trials of psilocybin therapy for treatment-resistant depression, sponsored by Compass Pathways, Ltd (EudraCT number 2017-003288-36 and 2020-001348-25), and of esketamine for treatment-resistant depression, sponsored by Janssen-Cilag, Ltd (EudraCT NUMBER: 2019-002992-33); has received payment, honoraria, or support for attending meetings and participating in advisory boards from MSD, Neurolite AG, Janssen Pharmaceuticals, Angelini Pharma, and the European Monitoring Centre for Drugs and Drug Addiction; has received consultancy fees from Bioprojet Pharma and NaturalX Health Ventures (all outside the submitted work); is Vice President of the Portuguese Society for Psychiatry and Mental Health; is head of the Psychiatry Working Group for the National Board of Medical Examination at the Portuguese Medical Association and Portuguese Ministry of Health; is President of the Ethics Committee for the Public Institute for Addictive Behaviors and Dependence; and is President of the Scientific Council of the Portuguese Obsessive Compulsive Disorder Foundation. The remaining authors declare that they have no potential conflicts of interest involving this work, including relevant financial activities outside the submitted work and any other relationships or activities that readers could perceive to have influenced, or that give the appearance of potentially influencing what is written. None of these agencies had a role in the design and conduct of the study, in the collection, management, analysis, and interpretation of the data, in the preparation, review, or approval of the manuscript, nor in the decision to submit the manuscript. Funding Information: The authors gratefully acknowledge the help of the Scientific Hardware and Software Development Platform at Champalimaud Foundation for providing the resources and technical support necessary for this work. DRS (2023.05754.BD) and FFV (2024.00723.BD) are funded by doctoral scholarships from Funda\u00E7\u00E3o para a Ci\u00EAncia e Tecnologia. GC is supported by a 2023 NARSAD Young Investigator Grant from the Brain & Behavior Research Foundation. AJO-M is supported by a Starting Grant from the European Research Council (grant agreement no. 950357), and by the PsyPal project (grant agreement no. 875358), both funded by the European Union's Horizon 2020 Research and Innovation Programme. GC and AJO-M are supported by a Proof-of-Concept Grant from the European Research Council (grant agreement no. 101158262). The content of this study is solely the responsibility of the authors and does not necessarily represent the official views of any of the funding agencies. Publisher Copyright: © 2025, MyJoVE Corporation. All rights reserved.
Palavras-chave
General Neuroscience General Chemical Engineering General Immunology and Microbiology General Biochemistry,Genetics and Molecular Biology