Table 2.
Results of the ANOVAs
| Study | d.f. | F-value | P-value |
|---|---|---|---|
| I–O curve | |||
| Intra DC (4-s tDCS) | |||
| DC | 2 | 17.763 | < 0.001* |
| TMS intensity | 3 | 52.101 | < 0.001* |
| DC × TMS intensity | 6 | 5.053 | < 0.001* |
| 7 min tDCS | |||
| DC | 3 | 22.706 | < 0.001* |
| TMS intensity | 3 | 25.733 | < 0.001* |
| DC × TMS intensity | 9 | 9.987 | < 0.001* |
| 9 or 13 min tDCS | |||
| DC | 3 | 4.725 | 0.008* |
| TMS intensity | 3 | 82.583 | < 0.001* |
| DC × TMS intensity | 9 | 2.953 | 0.004* |
| Double stimulation | |||
| Intra-tDCS (4-s tDCS) | |||
| DC | 2 | 6.947 | 0.003* |
| ISI | 4 | 23.408 | < 0.001* |
| DC × ISI | 8 | 1.975 | 0.053 |
| 7 min tDCS | |||
| DC | 3 | 25.334 | < 0.001* |
| ISI | 4 | 40.763 | < 0.001* |
| DC × ISI | 12 | 0.556 | 0.874 |
| 9 or 13 min tDCS | |||
| DC | 3 | 3.841 | < 0.001* |
| ISI | 4 | 11.802 | 0.018* |
| DC × ISI | 12 | 2.149 | 0.018* |
| I-waves | |||
| Intra-tDCS (4-s tDCS) | |||
| DC | 2 | 0.023 | 0.977 |
| ISI | 23 | 4.846 | < 0.001* |
| DC × ISI | 46 | 1.095 | 0.312 |
| 7 min tDCS | |||
| DC | 3 | 15.178 | < 0.001* |
| ISI | 23 | 28.880 | < 0.001* |
| DC × ISI | 69 | 1.420 | 0.015* |
| 9 or 13 min tDCS | |||
| DC | 3 | 4.179 | 0.013* |
| ISI | 23 | 10.314 | < 0.001* |
| DC × ISI | 69 | 0.843 | 0.813 |
Repeated-measures ANOVAs were calculated for the intra-tDCS and the after-effect parts of the study with regard to the I–O curve, intracortical inhibition and facilitation and I-wave protocols. Intra-tDCS refers to the 4 s tDCS protocol, which elicits no after-effects, with TMS applied during tDCS. 7 min tDCS refers to the tDCS protocol eliciting short-lasting after-effects (∼ 10 min duration), and 9 or 13 min tDCS to the tDCS protocol eliciting long-lasting after-effects (∼ 1 h duration). Degrees of freedom (d.f) differ for intra-tDCS and after-effect protocols. For the intra-tDCS-effects, there were three sessions (anodal tDCS, cathodal tDCS and no-tDCS), while for the after-effects, there were four conditions, due to the measure of the respective TMS protocols before and after anodal and cathodal tDCS, thus resulting in ‘before-anodal’, ‘before-cathodal’ and ‘after-anodal’ as well as ‘after-cathodal’ values. As can be seen from the results of the ANOVAs, tDCS modulated the I–O curve and intracortical inhibition/facilitation during tDCS as well as for the after-effects of tDCS, while the modulating effects of tDCS on I-waves were restricted to the after-effects.
P < 0.05.