Exploring the Cortical Hemodynamic Response of Excitatory Brain Stimulation: a Pilot Study

Study Overview
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Brief Summary
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Intermittent theta-burst stimulation (iTBS) is a promising treatment for major depressive disorder. However, fewer than 50% of patients show sufficient response. Therefore, the optimal treatment protocol is worth investigating. Recent studies show that the relationship between stimulation intensity and prefrontal hemodynamic response is not linear but in an inverse U-shape by exploring the hemodynamic changes before and after iTBS. Concurrent transcranial magnetic stimulation (TMS)/functional near-infrared spectroscopy (fNIRS) setup allows the investigators to observe the prefrontal hemodynamic response during stimulation. The aim of this study is to investigate the effects of different intensities on brain activity during and after the stimulation using fNIRS.

Detailed Description
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Please refer to the full proposal

Official Title
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Exploring the Cortical Hemodynamic Response of Excitatory Brain Stimulation: a Pilot Study

Conditions
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Healthy

Intervention / Treatment
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* Device: Intermittent theta-burst stimulation (iTBS)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Right-handed Exclusion Criteria: history of epilepsy, seizures, or convulsions current or past diagnosis of neurological disorders, such as head injuries, strokes, encephalitis, epilepsy, Parkinson's, or Alzheimer's current or past diagnosis of psychiatric disorders, such as depression, anxiety, schizophrenia, or autism with metal implants, such as a cochlear implant, neurostimulator, or cardiac pacemaker

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

Sexes Eligible for Study
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All

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: Healthy volunteers will receive iTBS three times with three different intensities separated by one week to investigate the prefrontal hemodynamic response to different stimulation intensities.
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Prefrontal hemodynamic response to 50% rMT iTBS<br>Participants will receive 50% rMT iTBS over left DLPFC in this arm. The prefrontal hemodynamic response will be observed simultaneously before, during, and after iTBS using fNIRS. | Device: Intermittent theta-burst stimulation (iTBS)<br>* The iTBS will be applied over lDLPFC with three different intensities. The investigators put the NIRS probe under the TMS coil to detect the hemodynamic signal simultaneously, and the applied rMT was adjusted based on Stokes et al., 2007. The equation is AdjMT% = MT + 2.8 * (Dsitex - Dm1), and the thickness of the probe is 6mm, therefore, 2.8*6=16.8(%) were added to the normal intensity.<br>* Other names: Transcranial magnetic stimulation (TMS);|
| Experimental: Prefrontal hemodynamic response to 70% rMT iTBS<br>Participants will receive 70% rMT iTBS over left DLPFC in this arm. The prefrontal hemodynamic response will be observed simultaneously before, during, and after iTBS using fNIRS. | Device: Intermittent theta-burst stimulation (iTBS)<br>* The iTBS will be applied over lDLPFC with three different intensities. The investigators put the NIRS probe under the TMS coil to detect the hemodynamic signal simultaneously, and the applied rMT was adjusted based on Stokes et al., 2007. The equation is AdjMT% = MT + 2.8 * (Dsitex - Dm1), and the thickness of the probe is 6mm, therefore, 2.8*6=16.8(%) were added to the normal intensity.<br>* Other names: Transcranial magnetic stimulation (TMS);|
| Experimental: Prefrontal hemodynamic response to 90% rMT iTBS<br>Participants will receive 90% rMT iTBS over left DLPFC in this arm. The prefrontal hemodynamic response will be observed simultaneously before, during, and after iTBS using fNIRS. | Device: Intermittent theta-burst stimulation (iTBS)<br>* The iTBS will be applied over lDLPFC with three different intensities. The investigators put the NIRS probe under the TMS coil to detect the hemodynamic signal simultaneously, and the applied rMT was adjusted based on Stokes et al., 2007. The equation is AdjMT% = MT + 2.8 * (Dsitex - Dm1), and the thickness of the probe is 6mm, therefore, 2.8*6=16.8(%) were added to the normal intensity.<br>* Other names: Transcranial magnetic stimulation (TMS);|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Oxygenated hemoglobin (HbO) change compared to baseline | iTBS-induced HbO change in the DLPFC before, during and after stimulation | During and post TBS-fNIRS measurement, up to 3 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Deoxygenated hemoglobin (HbR) Change compared to baseline | iTBS-induced HbR change in the DLPFC before, during and after stimulation | During and post TBS-fNIRS measurement, up to 3 months | 
| Oxygen saturation change compared to baseline | iTBS-induced oxygen saturation change in the DLPFC before, during and after stimulation | During and post TBS-fNIRS measurement, up to 3 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Theta-Burst stimulation (iTBS), Functional near-infrared spectroscopy (fNIRS), Concurrent TMS/fNIRS, Prefrontal hemodynamic response