Stimulating the criminal brain: Different effects of prefrontal tDCS in criminal offenders and controls

Aggression and anger are linked to an inability to adequately process social information and to regulate particularly negative emotions [1]. Reduced prefrontal brain activity and connectivity have been linked to emotion regulation deficits and increased aggressive and violent behavior [2]. Such dysfunctional brain processing might further increase the propensity to commit violent, criminal offences. Due to its potential to modulate brain activation and connectivity, transcranial direct current stimulation (tDCS) has been tested as a promising tool to counteract the aforementioned prefrontal hypoactivity. Specifically, anodal tDCS over the prefrontal cortex has demonstrated significant effects for improving emotion regulation [3] and reducing behavioral aggression in healthy controls [4]. However, the neural correlates of these beneficial effects remain unclear and the results must be replicated and validated in samples with particularly aggressive participants, such as criminal offenders. The current study was set up to tackle these two issues and increase our understanding on behavioral and neuronal tDCS effects on emotion regulation. Our main goal was to test the feasibility of prefrontal tDCS to improve emotion regulation in a group of criminal offenders and to further assess respective neural correlates of this effect via preand post-tDCS fMRI measurements (see Fig. 1B).