Table 1.
Three-way ANOVA with two between-subject factors (“TENS frequency”: high-frequency and low-frequency; “condition”: active and sham TENS) and one within-subject factor (“side”: laser stimuli delivered to hand dorsum ipsilateral and contralateral to TENS side) to assess TENS induced changes (Pre-TENS minus Post-TENS) of laser-elicited pain perception (pain intensity and unpleasantness) and brain responses (time domain: N1, N2, and P2 latencies and amplitudes; time-frequency domain: ERP and α-ERD magnitudes).
| Three-way ANOVA | Pain intensity | Pain unpleasantness | N1 latency | N1 amplitude | N2 latency | N2 amplitude | P2 latency | P2 amplitude | ERP magnitude | α-ERD magnitude | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| TENS frequency | F = 0.54 | F = 1.40 | F = 2.75 | F = 0.004 | F = 4.51* | F = 0.16 | F = 1.63 | F = 0.06 | F = 1.58 | F = 0.19 | |
| Condition | F = 27.37*** | F = 35.87*** | F = 8.05*** | F = 42.79*** | F = 2.80 | F = 29.56*** | F = 8.03** | F = 40.94*** | F = 33.02*** | F = 0.65 | |
| Side | F = 10.41*** | F = 10.71*** | F = 0.61 | F = 8.16** | F = 2.34 | F = 4.33* | F = 15.07*** | F = 3.41 | F = 1.96 | F = 0.99 | |
| TENS frequency × condition | F = 0.46 | F = 0.08 | F = 0.04 | F = 0.35 | F = 0.004 | F = 1.33 | F = 1.58 | F = 1.17 | F = 0.55 | F = 0.40 | |
| TENS frequency × side | F = 0.11 | F = 0.78 | F = 1.09 | F = 0.06 | F = 1.91 | F = 2.84 | F = 5.22* | F = 4.28* | F = 1.87 | F = 1.03 | |
| Condition × side | F = 2.86 | F = 0.92 | F = 0.72 | F = 1.16 | F = 2.70 | F = 0.78 | F = 3.03 | F = 1.75 | F = 4.34* | F = 0.17 | |
| TENS frequency × condition × side | F = 5.90* | F = 4.32* | F = 0.07 | F = 5.48* | F = 1.68 | F = 0.41 | F = 0.06 | F = 4.34* | F = 6.47** | F = 0.96 | |
| Post hoc two-way ANOVA | |||||||||||
| High-frequency TENS |
condition | F = 15.09*** | F = 18.02*** | -- | F = 29.93*** | -- | -- | -- | F = 28.90*** | F = 23.85*** | -- |
| side | F = 9.87** | F = 13.21*** | -- | F = 5.93* | -- | -- | -- | F = 6.99** | F = 2.93 | -- | |
| condition × side |
F = 13.21*** |
F = 7.05** |
-- |
F = 7.17** |
-- |
-- |
-- |
F = 5.29* |
F = 8.19** |
-- |
|
| Low-frequency TENS |
condition | F = 12.30*** | F = 17.91*** | -- | F = 15.39*** | -- | -- | -- | F = 13.69*** | F = 11.20** | -- |
| side | F = 3.08 | F = 2.12 | -- | F = 2.87 | -- | -- | -- | F = 0.03 | F = 0.001 | -- | |
| condition × side | F = 0.20 | F = 0.47 | F = 0.67 | -- | -- | -- | F = 0.32 | F = 0.15 | -- | ||
*: p < 0.05; **: p < 0.01; ***: p < 0.001.