tDCS procedure: There is a total of 30 minutes of stimulation at the intensity of 2mA (ramp up and ramp down: 30 sec). Sham stimulation consists in delivering 1 minute of real stimulation. The stimulation site (DLPFC) will be anatomically determined according to 10/20 EEG system (F3 & F4). This procedure is in accordance with international guidelines for safety. Safety and blinding will be assessed using specific tools at the end of the protocol.