Modulation of Motor Cortex Excitability by TMS and tDCS (MAGS1)

Study Overview
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Brief Summary
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Investigating modulation of motor cortex excitability by transcranial magnetic stimulation and transcranial direct current stimulation.

Detailed Description
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Purpose of this pilot study is to modulate the motor cortex excitability by transcranial magnetic stimulation and transcranial direct current stimulation. Electromyography will be recorded on right abductor digiti minimi muscle to find the motor threshold and measure motor evoked potentials for each healthy participant. In addition, electroencephalography (EEG) data will be collected on the scalp with a high-density EEG net. Eighteen healthy participants will be in this study. Each participant will be seated in a reclining chair and applied non-invasive magnetic and electrical stimulations on the scalp. At baseline, the participant's resting motor threshold (RMT) will be estimated by adjusting the intensity of TMS applied on the left motor cortex to achieve motor-evoked potentials of about 50 uV with 10 TMS pulses at a rate of 0.25 Hz. Then a 3-condition, 3-session, 6-sequence randomized crossover experiment will be used to characterize and compare three versions of tDCS stimulation: anode, cathode, sham. Before and after a 10-min tDCS condition is applied, TMS pulses at 120% of RMT intensity will be applied for 10 minutes and TMS-evoked potential and motor-evoked potential amplitudes will be measured. Each session has at least 1-day gap to remove outlasting effects. We will also be collecting structural magnetic resonance imaging (sMRI) to target primary motor cortex precisely.

Official Title
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Modulation of Motor Cortex Excitability by Transcranial Magnetic Stimulation and Transcranial Direct Current Stimulation

Conditions
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Motor Activity, Motor Neuroplasticity

Intervention / Treatment
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* Device: anodal tDCS
* Device: cathodal tDCS
* Device: sham tDCS


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male Between the ages of 18 and 35 Right-handed Capacity to understand all relevant risks and potential benefits of the study (informed consent) Willing to comply with all study procedures and be available for the duration of the study Speak and understand English Exclusion Criteria: Prior concussion Diagnosis of eating disorder (current or within the past 6 months) Diagnosis of obsessive compulsive disorder (lifetime) Attention-deficit/hyperactivity disorder (currently under treatment) Neurological disorders and conditions, including, but not limited to: History of epilepsy Seizures (except childhood febrile seizures and electroconvulsive therapy-induced seizures) Dementia History of stroke Parkinson's disease Multiple sclerosis Cerebral aneurysm Brain tumors Medical or neurological illness or treatment for a medical disorder that could interfere with study participation (e.g., unstable cardiac disease, HIV/AIDS, malignancy, liver or renal impairment) Prior brain surgery Any brain devices/implants, including cochlear implants and aneurysm clips Traumatic brain injury Anything that, in the opinion of the investigator, would place the participant at increased risk or preclude the participant's full compliance with or completion of the study

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Each participant will be assigned to 2 active and sham conditions on a different day.
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: anodal tDCS<br>Two electrodes will be applied to the scalp (one on the left motor cortex, one on the right supraorbital cortex). This anodal tDCS on the left motor cortex will be stimulated with 2mA for 10 minutes. | Device: anodal tDCS<br>* The participant will receive anodal tDCS with 2 mA for 10 minutes on the left motor cortex.<br>|
| Active Comparator: cathodal tDCS<br>Two electrodes will be applied to the scalp (one on the left motor cortex, one on the right supraorbital cortex). This cathodal tDCS on the left motor cortex will be stimulated with -2mA for 10 minutes. | Device: cathodal tDCS<br>* The participant will receive cathodal tDCS with -2 mA for 10 minutes on the left motor cortex.<br>|
| Sham Comparator: sham tDCS<br>Two electrodes will be applied to the scalp (one on the left motor cortex, one on the right supraorbital cortex). Sham stimulation with 2mA for 40 seconds will be applied. | Device: sham tDCS<br>* The participant will receive sham tDCS with 2 mA for 40 seconds on the left motor cortex which mimics the skin sensations as active tDCS interventions.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in Motor-evoked Potentials Ratios | The investigators will record motor-evoked potentials and calculate changes in between before and after 2mA tDCS stimulation for 10 minutes. | right before and after 2mA tDCS stimulation for 10 minutes at each session | 
| Changes in TMS-evoked Potentials Ratios | The investigators will record TMS-evoked potentials using EEG and calculate changes in between before and after 2mA tDCS stimulation for 10 minutes. | right before and after 2mA tDCS stimulation for 10 minutes at each session | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in Resting-state EEG Dynamics Ratios | The investigators will record participants' resting state for 4 minutes using EEG (2 minutes for eyes-closed and 2 minutes for eyes-open) | 4 minutes recordings before and after each 2mA tDCS stimulation for 10 minutes at each session | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), electroencephalography (EEG)