TABLE 4.
tES effect detected by fNIRS.
| Reference | Electrode position (anode–cathode and “i” = ipsilateral; “c” = contralateral) | Optode position | Stimulation parameter | Measurement | Motor task | Effects | Cohort | ||||||
| I (mA) | J (mA/cm2) | t (min) | f (Hz) | Days | HbO | HbR | connectivity | ||||||
| Khan et al. (2013) | iM1-cM1 cM1-iM1 | PMC, M1, S1, PPC | 2 | 0.08 | 15 | 0 | 1 | • | • | Muscle contraction | Online and short term (after intervention) | Healthy | |
| Khan et al. (2015) | iM1-cM1 20 combinations between PMC, M1 and SO | PMC, M1, S1, PPC | 0.5 | 0.02 | 0.67 | 0 | 1 | • | Force tracking | Short term (5 min) | Healthy and Stroke | ||
| Angius et al. (2016) | iM1-cSO iM1-shoulder | PFC | 2 | 0.17 | 10 | 0 | 1 | ∘ | ∘ | Muscle contraction | Short term (after intervention) | Active males | |
| Muthalib et al. (2016) | M1-radial | Sensorimotor | 2 | 0.67 | 10 | 0 | 1 | • | Sequential finger opposition | Online and short term (3 min) | Healthy | ||
| Choe et al. (2016) | M1-radial DLPFC-radial | Left M1, right DLPFC | 2 | 0.04 | 60 | 0 | 4 | ∘ | ∘ | Pilot training | Online | Healthy | |
| Radel et al. (2017) | PFC region | Right lateral PFC and the right M1 | 2 | 0.32 | 20 | 0 | 1 | • | Muscle contraction | Online and short term (after intervention) | Healthy | ||
| Berger et al. (2018) | Parietal | M1 | 1 | 0.3 | 20 | 0 | 1 | • | Bimanual joysticks | Short term (0 s, 30 min) and long term (1 day) | Healthy | ||
| Ciechanski et al. (2019) | iM1-cSO | 32 channels | 1 | 1.27 | 20 | 0 | 1 | Enhanced the motor performance; an increment in beta power | Surgical task | Online and short term (after intervention) | Healthy | ||
| MEG | |||||||||||||
| Krause et al. (2014) | iM1-cSO | 306 channels | 1 | 0.03 | 15 | 10;20 | 1 | Attenuated beta band CMC during isometric contraction after 20-Hz tACS | Forearm isometric contraction | Short term (after intervention) | Parkinson disease and healthy | ||
| Hanley et al. (2016) | Oz - Cz; C3 - Fp2 | 275 channels | 1 | 0.03 | 10 | 0 | 1 | Significantly modulated motor-evoked responses | Right index finger abduction | Online and short term (after intervention) | Healthy | ||
| Sugata et al. (2018) | iM1-cSO | 306 channels | 1 | 0.03 | 10 | 10;20;70 | 1 | A significant increase in beta-band power after 70-Hz tACS | Finger tapping | Short term (after intervention) | Healthy | ||
“∘” means no significant change observed. PMC, premotor cortex; S, primary somatosensory cortex; PPC, posterior parietal cortex. Sequential finger opposition: sequential tapping of the index, middle, ring, and fourth finger against the thumb. In “Effects” section, “online” refers to motor changes happened during the tES, “short term” refers to changes in a short time (<1 day) after the tES, “long term” refers to changes in a long time (>1 day) after tES.