Table 2 Effects of rTMS stimulation to M1 on fNIRS measurement in healthy subjects
References | Study design | No. of subjects | Stimulation parameters | Sham stimulation | Stimulation area | fNIRS specifications | fNIRS measurement area | Timing of measurement | Task | Findings |
|---|---|---|---|---|---|---|---|---|---|---|
Hada et al., 2006 | Single-blind, within-subject design | 12 right-handed healthy subjects | rTMS, 10 times (1)120% RMT, 2 Hz (2)120% RMT, 0.5 Hz (3) 80% RMT, 2 Hz (4) 80% RMT, 0.5 Hz | N/A | Left M1 | OMN-2001 Shimadzu Corp. Japan (A pair of NIRS probes attached to the rTMS coil) | Left M1 | During rTMS | Rest | - Decreased [Hb] [HbO], increased [HbD] at the ipsilateral M1 in all groups. - Mildly increased [Hb] and [HbO] after 5s of rTMS at the ipsilateral M1 in the 120% RMT groups. |
After rTMS (for 3Â min) | Rest | - Greatest peaks of [Hb] [HbO] decrement and [HbD] increment just after rTMS | ||||||||
Chiang et al., 2007 | Single-blind, within-subject design | 5 right-handed healthy subjects | (1) rTMS, 115% RMT, 1Â Hz for 20Â min (2) Sham | A non-discharging coil and a real stimulation placed at 90 degrees | Right M1 | NIRO-200 monitor Hamamatsu Photonics KK | Left M1 | After rTMS (for 115Â min, intermittent) | Finger tapping task | - Increased [HbO] at the contralateral M1, for 40Â min. - Decreased [HbD] at the contralateral M1, for 15Â min. |
Mochizuki et al., 2007 | Single-blind, within-subject design | 8 right-handed healthy subjects | (1) iTBS, 80 or 100% AMT. triple-pulse burst 50Â Hz* 10 bursts, 30 pulses (2) Sham | A non-discharging coil at the stimulation site a real stimulation 10Â cm above the head | Left PM, M1 or S1 | ETG-A1; Hitachi Medical Corp. Japan (4 pairs of emitters and detectors) | Right prefrontal cortex, PM, M1 and S1 | During rTMS | Rest | - iTBS over M1 elicited decreased [HbO] at the contralateral M1. |
Kozel et at., 2009 | Observational | 11 healthy subjects | rTMS, 120% RMT, 1Â Hz, 10 pulses* 15 trains * 2 sessions | N/A | Left M1 then the left PM | CW5, TechEn Inc, USA (8 sources and 16 detectors) | Bilateral M1 then PM | During rTMS | Rest | - Decreased [HbO] at the bilateral M1, with less decrement at the ipsilateral versus the contralateral M1. |
Hirose et al., 2011 | Single-blind, within-subject design | 9 right-handed healthy subjects | QPS, 110% AMT, 24 bursts (1) QPS-5: ISI = 5 ms (2) QPS-50: ISI = 50 ms (3) Sham | A non-discharging coil at the stimulation site, and a real stimulation 10 cm above the head | Left M1 | ETG-4000; Hitachi Medical Corp., Japan (5 pairs of emitters and detectors) | Right M1, PM and S1 | During QPS | Rest | - Decreased [HbO] at contralateral M1, PM and S1 in QPS-5 vs. sham. - Decreased [HbO] at contralateral M1 in QPS-50 vs. sham. |
Nasi et al., 2011 | Observational, controlled | 10 healthy subjects | rTMS, 75% RMT, at 0.5, 1, and 2Â Hz in 8s * 25 trains | N/A | Left M1 (Control group: Left shoulder) | 2 sources and 6 detectors | Bilateral M1 | During rTMS | Rest | - Decreased [Hb] (mostly [HbO]) at the bilateral M1 in the 2Â Hz group. |
Tian et al., 2012 | Observational (test-retest reliability assessment) | 11 healthy subjects | rTMS, 120% RMT, 1Â Hz, 10 pulses* 15 trains * 2 sessions | N/A | Left M1 then the left PM | CW5, TechEn Inc., USAÂ (8 sources and 16 detectors) | Bilateral M1 then PM | During rTMS | Rest | - Decreased [HbO] at the bilateral M1 and PM with a moderate to high reliability. |
Groiss et al., 2013 | Single-blind, within-subject design | 10 healthy subjects | QPS, 90% AMT, 0.2 Hz (1) 24 bursts * 3 trains of QPS-5 or QPS-50 (2) 10 bursts of QPS-5 and QPS-50 each (3) Sham | Sham stimulation with ISI = 5 ms (SHAM-5) or 50 ms (SHAM-50) | Left M1 | ETG-4000; Hitachi Medical Corp., Japan (5 pairs of emitters and detectors, 24 channels) | Left M1, S1, PM, SMA and PFC. | During QPS | Rest | - Decreased [HbO] during QPS-5 at the ipsilateral M1 and PM compared to baseline level and sham. |
After QPS (for 55–180 s) | Rest | - [HbO] decrement mentioned above peaked at 10s after QPS-5 and returned to baseline level at 20s after QPS-5. | ||||||||
Mesquita et al., 2013 | Observational | 7 right-handed healthy subjects | rTMS, 95% RMT, 1Â Hz, totally 1200 pulses | N/A | Left M1 | Self-designed diffuse correlation/ optical spectroscopy | Bilateral M1 | During rTMS | Rest | - Increased CBF and [HbO] at the ipsilateral M1. No change at the contralateral M1. |
After rTMS (for 4Â min) | Rest | - Increased CBF and [HbO] at the ipsilateral M1 compared to baseline levels. | ||||||||
Park et al., 2017 | Single-blind, within-subject design | 10 right-handed healthy subjects | (1) rTMS, 90% RMT, 1Â Hz, totally 1200 pulses (2) Sham | A disconnected figure-of-eight coil | Left M1 | OMM-3000; Shimadzu, Japan. (8 pairs of emitters and detectors) | Right M1 and PM | During rTMS | Rest | - Increased [HbO] at the contralateral M1, decreased [HbD] at the contralateral M1 and PM compared to sham. |
After rTMS (for 20Â min) | Rest | - The above changes lasted for at least 20Â min after rTMS compared to baseline levels. | ||||||||
Li et al., 2019 | Observational | 20 right-handed healthy subjects | rTMS, 90% RMT, 10 Hz, 40 trains (each train 2s stimulation + 28s rest) | N/A | Bilateral PFC, PM, M1, middle PFC and SMA | NIRx Medical Technologies, USA (16 emitters and 15 detectors, 46 channels) | Where the rTMS stimulation was | During rTMS | Rest | - Decreased [HbO] and HbO AUC at the bilateral M1 with gradual recovery. - Decreased functional connectivity within prefrontal areas as well as between symmetrical M1-pairs. |
After rTMS | Rest | - The above [HbO] and HbO AUC decrements returned to baseline levels within 5Â min. | ||||||||
Kim et al., 2020 | Single-blind, crossover design | 10 right-handed healthy subjects | (1) rTMS, 100% RMT, 1 Hz, totally 1200 pulses (2) Sham | Diverting the coil 90 degrees with the same stimulation | Left M1 HK, Left M1 hMHS | NIR Scout ®; NIRx Medical Technology, Germany. (8 sources and 16 detectors, 31 channels) | Right M1 | During and after rTMS | Serial reaction time task | - Increased integral value of HbO at the contralateral M1 after hMHS-rTMS compared to baseline. |
Li et al., 2022 | Double-blind, RCT | 40 right-handed healthy subjects | 80% RMT (1) pcTBS: 50Â Hz, 3 pulses* 400 times (2) iTBS: 50Â Hz, 3 pulses * 10 times (3) rTMS: 10Â Hz, 10Â s * 15 trains (4) Sham | Present but not defined | Left M1 | BS-3000, Wuhan Znion Technology Co., Ltd., China. (12 pairs of emitters and detectors, 37 channels) | Bilateral prefrontal area | Right after rTMS | Pain Tolerance Threshold (PTT) | - Increased [HbO] at the bilateral DLPFC in the pcTBS and iTBS groups when compared to other certain groups. |
60Â min after rTMS | PTT | - Increased [HbO] at the bilateral DLPFC and FPC in the pcTBS and 10Â Hz rTMS groups compared to other certain groups. - Increased [HbO] at the ipsilateral DLPFC compared to baseline in the pcTBS group. | ||||||||
Gorban et al., 2023 | Single-blind, within-subject design | 10 right-handed healthy subjects | 80% AMT (1) cTBS: 50 Hz of 3 pulses, total 600 pulses (2) iTBS: 2 s trains of TBS, total 600 pulses (3) Sham | Active coil tilted 90° | Left M1 (hand region) | Frequency-Domain Multi-Distance NIRS, Imagent, ISS, Champaign IL, USA | Left M1 (hand region) | After rTMS | Evoked change after a single-pulse TMS (100% RMT) & sham stimulus | - Increased [Hb] after cTBS compared to baseline - A trend of increased [HbO] change after cTBS, but not statistically significant. |