Targeting aggression with prefrontal high-definition transcranial direct current stimulation

Heightened aggression is associated with behavioural and neural deficits in inhibitory control. Transcranial direct current stimulation (tDCS) shows promise in facilitating inhibitory control and reducing aggression. However, the mixed effects and widespread electric fields of tDCS warrant more precise stimulation methods. High-definition tDCS (HD-tDCS) may enhance focality to target the right inferior frontal gyrus (rIFG), a key region in inhibitory control. In a double-blind and sham-controlled study, we investigated behavioral and neural differences between anodal and sham HD-tDCS in a subsequent Taylor Aggression Paradigm (TAP). Anodal HD-tDCS was applied at 1.5 mA for 20 min over the rIFG. Reference electrodes were located at TP8, PZ, FC3, and FP1. 41 healthy male participants were randomly assigned to either anodal (19) or sham (22) HD-tDCS and completed the TAP during functional magnetic resonance imaging. Anodal HD-tDCS did not directly reduce aggression; however, the stimulation weakened the effect of provocation on aggressive behaviour. Imaging results indicated that anodal HD-tDCS was associated with a positive provocation-related increase of bilateral parietal lobule (IPL) activation. Taken together, behavioural and neuroimaging findings suggest that anodal rIFG stimulation may engage the inhibitory control network as reflected in reduced responsiveness to provocation and increased activation during provocation.