High-definition transcranial direct current stimulation of the dorsal anterior cingulate cortex modulates decision-making and executive control.

Previous neuroimaging evidence highlights the translational implications of targeting the dorsal anterior cingulate cortex (dACC), i.e. a key node of the networks underlying conflict monitoring and decision-making, in brain stimulation treatments with clinical or rehabilitative purposes. While the optimized modelling of "high-definition" current flows between multiple anode-cathode pairs might, in principle, allow to stimulate an otherwise challenging target, sensitive benchmark metrics of dACC neuromodulation are required to assess the effectiveness of this approach. On this basis, we aimed to assess the modulatory effect of anodal and cathodal high-definition tDCS (HD-tDCS) of the dACC on different facets of executive control and decision-making in healthy young individuals. A combined modelling/targeting procedure provided the optimal montage for the maximum intensity of dACC stimulation with six small "high-definition" electrodes delivering anodal, cathodal or sham HD-tDCS for 20 min in a within-subject design with three separate sessions. Following stimulation, participants performed Flanker and gambling tasks unveiling individual differences in executive control and both loss- and risk-aversion in decision-making, respectively. Compared to both anodal and sham conditions, cathodal dACC stimulation significantly affected task performance by increasing control over the Flanker conflict effect, and both loss and risk-aversion in decision-making. By confirming the feasibility and effectiveness of dACC stimulation with HD-tDCS, these findings highlight the implications of modelling and targeting procedures for neuromodulation in clinical research, whereby innovative protocols might serve as treatment addressing dysfunctional dACC activity, or combined with cognitive training, to enhance higher-order executive functioning in different neuropsychiatric conditions.