2.4. Transcranial direct current stimulation
bipolar
tDCS was administered using two saline-soaked surface sponge electrodes, each with an area of 5x7 cm2, connected to the battery-driven NeuroConn DC stimulator MR. To target the right DLPFC unilaterally, a bipolar non-balanced configuration was employed based on "Beam F3-system" [During active stimulation, tDCS was delivered for 20 minutes at an intensity of 2 mA, with a 30-second ramp-like fade-in, followed by 19 minutes of active stimulation, and a 30-second ramp-like fade-out. For the sham stimulation procedure, the stimulator automatically turned off after 100 seconds, consisting of a 30-second ramp-like fade-in, 40 seconds of active stimulation, and a 30-second ramp-like fade-out. This simulated the typical sensations induced by tDCS. In the sham group, the fade-out was followed by 18.3 minutes without any further stimulation, during which impedance was periodically checked to ensure the average current over time did not exceed 2 μA. Throughout both active and sham tDCS sessions, the impedance was maintained below 10 k-Ohm.