Table 3.
List of NIBS studies
| First author | Number of subjects | Stimulation electrode location | Reference electrode location | Polarity | Blind | Current density (mA/cm2) | Stimulation duration (min) | Number of sessions | Assesment | Task | Result |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Brunoni et al. (2013) | 20, healthy subjects, 24.9 ± 3.8 | L DLPFC | R DLPFC | A/C/S | Single blind | 0.04 | 33 | 1 | HRV and salivary cortisol | Picture-induced stress | Left anodal tDCS inhibited cortisol and enhanced vagal tone |
| Antal et al. (2014) | 60, 25 ± 6 | R mPFC (F2-FPz) | O2-P4 | A/C/S | Double blind | 20 | Salivary cortisol, fMRI | Task-induced stress | Anodal stimulation inhibited cortisol and increased rCBF in the right mPFC (compared with sham stimulation) and increased rCBF in the right amygdala and PFC. Cathodal stimulation increased cortisol levels | ||
| Feeser et al. (2014) | 42, 29.8 ± 6.2 | R DLPFC | Left supraorbital region | A/S | Double blind | 0.04 | 20 | 1 | SCR and eye tracking | Picture-induced stress | Depending on the goal, tDCS can upregulate or downregulate cognitive appraisal |
| Sarkar et al. (2014) | 23.54 ± 3.11 | L DLPFC (F3) | R DLPFC (F4) | A/S | Double blind | 0.04 | 30 | 2 crossover | Salivary cortisol | Mathematics task | tDCS improved reaction times on simple arithmetic decisions and decreased cortisol concentration in subjects with high levels of mathematics-related anxiety. In contrast, tDCS increased reaction times for subjects with low levels of mathematics-related anxiety and prevented a decrease in cortisol concentration compared with sham stimulation |
| Schroeder et al. (2015) | 22, rejected: 4, 3 male, 31.3 ± 2.5 | L DLPFC (F3) | Right upper arm | A/S | Double blind | 0.02 | 20 | 2 crossover | SCR | Delayed responses in working memory task and emotional picture task | Anodal stimulation reduced SCR to emotional pictures |
| Okano et al. (2015) | 10, 33 ± 9 | T3 | Fp2 | A/S | Single blind | 0.05 | 20 | 2 crossover | HR, R–R interval | Physical workload (cycling) | Anodal stimulation improved cycling performance while reducing HR and delaying parasympathetic vagal tone |
| Austin et al. (2016) | 66 female, 21.6 ± 2.3 years | F3 | F4 | A/S | E1: single blind, E2: double blind | 0.06 | 12 | E1: 5, E2: 3 | Mood assessment questionnaire | Prefrontal stimulation successfully improved mood states in non-depressed individuals | |
| Bogdanov and Schwabe (2016) | 120, 60 female, 25.2 ± 0.31 | DLPFC (F4) | Cz | A/C/S | Double blind | 0.043 for active and 0.011 for reference electrode location | 1 | Subjective measures with BP, blood pulse and salivary cortisol | Stressor manipulation | Anodal stimulation led to improved working memory performance after stress | |
| Raimundo et al. (2012) | 50 | M1-L (C3) | Right supraorbital region (FP2) | A/S | Double blind | 0.03 | 10 | 1 | BP, BT, HR, RR, plasma cortisol | None | Both active and sham stimulation significantly changed hand skin temperature and cortisol with active stimulation having no significant difference to sham stimulation |
| Vigod et al. (2014) | 20–40 | F3 | F4 | A/S | Double blind | 0.57 | 15–30 | 15 | BR, HR | None | tDCS is predicted to result in significant improvement of depression without affecting autonomic rate, core body temperature and ventilation rate |
| Hamner et al. (2015) | 15, 21–30 years | M1-L (C3) | Right supraorbital region (FP2) | A/S | 0.57 | 40 | 2 crossover sessions with minimum 7 days to maximum 8 weeks separation | BP, HR, leg blood flow and leg vascular resistance | Cold pressor test | Anodal tDCS at C3 did not affect basal hemodynamics or ANS and had only modest effects on responses to acute pain in healthy subjects |
M male subjects, f female subjects, E1 experiment 1, E2 experiment 2