Figure 1. tDCS electrode configurations, current settings, and electric field distribution. A, Dual-target group (lDLPFC+rM1 tDCS) or sham group. B, Single-target tDCS (lDLPFC tDCS). C, Single-target tDCS (rM1 tDCS). The electric field simulation diagram was generated using HD Explore software (Soterix, USA).

Figure 2. Experimental design. A, Thermal and pressure stimulation application. B, Flowchart of Experiment 1. C, Capsaicin induced pain application. D, Flowchart of Experiment 2. ISI: Interstimulus interval.

Figure 3. Results of Experiment 1. A, The analgesic effect of tDCS on transient thermal pain intensity. B, The modulatory effect of tDCS on pressure pain threshold. C, Correlation analysis between the changes in pain intensity ratings in the lDLPFC+rM1-tDCS group and the scores from the fear of pain questionnaire. Error bars represent the standard error of the mean (SEM), and data are expressed as Mean ± SEM. Significance levels are indicated as follows: * p < 0.05, ** p < 0.01. HP, High pain level. MP, Moderate pain level.

Figure 4. Results of Experiment 2. A, The analgesic effect of tDCS on capsaicin-induced sustained pain intensity across different time points. B, The analgesic effect on the sustained pain during tDCS modulation. Error bars represent the standard error of the mean (SEM), and data are expressed as Mean ± SEM. Significance is denoted as follows: * or O for p < 0.05, ** for p < 0.01. * represent a significant difference between the dual-target group and Sham group, and O represents a significant difference between the dual-target group and single-target group following post hoc pairwise comparison.