| Violent offenders account up to 70% of the prison population and 50%-80% of the offenders meet the diagnostic criteria of antisocial personality disorder.They show executive functioning deficits,insensitivity or resistance to punishment or related treatment,with significant potential for social harm.Transcranial direct current stimulation(t DCS)and cognitive training are two promising treatments for antisocial populations.t DCS is a noninvasive brain stimulation tool that induces changes in brain function by altering the activity and excitability of cortical neurons through weak direct current generated by electrodes placed in the skull.Cognitive training helps individuals learn to integrate the context clues to improve the contextual attention deficit and the cognitive control ability of emotion.t DCS and cognitive training have shown initial effectiveness in reducing aggression,improving emotional cognitive control,and enhancing empathy and social morality.However,no studies have yet explored the effects of t DCS and cognitive training on violent offenders’ executive functioning,especially inhibitory control and decision making.How to develop scientific and efficient intervention methods for violent offenders is of great significance to social stability and the safety of people’s lives and properties.In this study,48 violent offenders were randomly divided into t DCS group,t DCS sham group,cognitive training group and control group using a parallel,control,single-blind experimental design.In the experiment,the t DCS group received high-definition t DCS(HDt DCS)for 20 minutes in 5 consecutive days,and the stimulation target was selected as the left dorsolateral prefrontal cortex(DLPFC).t DCS sham group received sham HD-t DCS for five consecutive days.The cognitive training group received three kinds of learning tasks:probabilistic reversal learning,divided visual field and affective gaze task,once a day for five days.The control group did not do any intervention.Before and after the intervention,the participants in the four groups completed the Oddball paradigm,emotional Go-No Go task,and a simple gambling task respectively,and this study collected behavioral data.Meanwhile,the changes of behavioral indexes and brain activities of all groups before and after the intervention were compared with Event-related potentials(ERP).This study aimed to investigate and compare the effect of HD-t DCS and cognitive training on executive function of violent offenders,in order to find effective treatment programs.Results showed:(1)The accuracy of Oddball paradigm in each group changed little after intervention,while the response time of t DCS group increased after intervention.Likewise,violent offenders increased response time and accuracy in Go-No Go task after HD-t DCS intervention,although the difference was not significant.In a certain extent,HD-t DCS can improve the cognitive function in terms of behavioral indicators;(2)After HD-t DCS intervention,the amplitude of P3 induced by negative stimulus of Oddball paradigm increased only in the frontal region,and the latency was shortened in the central and parietal regions,while the amplitude of P2 induced by negative stimulus increased in the frontal and central regions,and the latency was shortened in the central and parietal regions;(3)Both two methods induce increased No Go-P3 amplitude induced by negative faces in the central region,while HD-t DCS shortens the No Go-P3 latency and mean amplitude induced by negative faces.The effect of HD-t DCS over the DLPFC improved the inhibition of motor response and the ability to evaluate the inhibitory results of violent offenders;(4)In the reward gate task,t DCS group and the cognitive training group showed reduced P3 amplitude after the intervention,and the difference between the P3 amplitude induced by loss and profit feedback decreased after the intervention.Therefore,the sensitivity of violent criminals to beneficial feedback and the attention bias to reward cues decreased under the intervention of HD-t DCS and cognitive training;(5)ERP components change non-significantly.The intervention effects of HD-t DCS and cognitive training on executive functioning of offenders still needs to be further explored.The ineffective effect may be limited by several important factors such as t DCS parameter setting,implementation intensity and frequency of cognitive training tasks,and heterogeneity of antisocial populations.Therefore,future research should develop accurate treatment programs for violent offenders based on group heterogeneity. |
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