Endogenous dopamine release under transcranial direct-current stimulation governs enhanced attention: a study with positron emission tomography

The placement of the tDCS electrodes was based on the international 10–20 EEG system: the anode at the F3 (left DLPFC) and the cathode at the F4 (right DLPFC) a. The type of stimulation (active or sham) was randomized in a double-blind manner. Thirteen-minutes duration tDCS was applied twice with an interval of 20？min. PET was performed at 50？min after initiation of tDCS, followed by MRI measurement at 140？min and cognitive tests at 200？min, respectively. Participants underwent twice experiments in a crossover fashion at least 1 month apart