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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.
Please refer to the full proposal
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Prefrontal hemodynamic response to 50% rMT iTBS | Experimental | 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. |
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| Prefrontal hemodynamic response to 70% rMT iTBS | Experimental | 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. |
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| Prefrontal hemodynamic response to 90% rMT iTBS | Experimental | 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. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Intermittent theta-burst stimulation (iTBS) | Device | 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. |
| 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 |
| 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 |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Georg S Kranz, PhD | The Hong Kong Polytechnic University | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| The Hong Kong Polytechnic University | Hong Kong | Hong Kong |
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| ID | Term |
|---|---|
| D050781 | Transcranial Magnetic Stimulation |
| ID | Term |
|---|---|
| D055909 | Magnetic Field Therapy |
| D013812 | Therapeutics |
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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.
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Participants will not be informed of the stimulation intensities.
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iTBS-induced oxygen saturation change in the DLPFC before, during and after stimulation
| During and post TBS-fNIRS measurement, up to 3 months |