Stimulating the left dorsolateral prefrontal cortex reduces attentional bias for intergroup threat

Abstract

Attentional bias (AB) towards threat is a common phenomenon in the context of intergroup threat, which plays an important role of protection for individuals. However, sustaining attentional bias towards the information of intergroup threat has a lot of negative effects on people’s life and social interaction. For example, it not only occupies cognitive resources, but also brings anxiety and interferences with individual’s judgment, even causes conflicts and contradictions among groups. So, it is significant to reduce excessive attention bias toward intergroup threat appropriately for the effective communication and cooperation among individuals and groups. According to Neurocognitive models of selective attention to threat, the allocation of attention in the presence of threat is regulated by two primary neural systems: a bottom-up amygdala-based system and a top-down system relying on the dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortices (ACC). The first system would be related to the rapid response to the perceived salience of threatening stimuli in the environment, while the second system would be related to attentional control, responsible for regulating the attention to threatening stimuli. In this perspective, the attentional bias towards threat would be related to an increase of amygdala activation and a reduced activity of the DLPFC. What’s more, reducing AB via attention bias modification (ABM) procedures is associated with increased activation of the left dorsolateral prefrontal cortex (DLPFC). These suggested that DLPFC, in particular in the left hemisphere, is involved in the attentional control in presence of threatening stimuli. Therefore, in the present study, the causal role of the left DLPFC on AB towards intergroup threat was investigated by using the transcranial direct current stimulation (tDCS) technique during the completion of a dot-probe measure task. The transcranial direct current stimulation (tDCS), another non-invasive method of brain stimulation, which is able to reach the modulation of the cortical activities t through electrodes positioned over one’s scalp. Anodal stimulation facilitates cortical activity, whereas cathodal stimulation has opposite effects. In the present study, to stimulate the left dorsolateral prefrontal cortex, the anode electrode was positioned centered over the F3 according to the 10–20 international system and the reference electrode was placed at the ipsilateral arm. The results are as follows: compared to the sham stimulation; anodal tDCS exhibited a significant reduction in attentional bias towards intergroup threat. Further, the reaction time of target after threatening group significantly shorter than that after non-threatening group in sham group; we didn’t find attentional Bias for Intergroup threat in anodal group. Finds suggested that Anodal tDCS over the left DLPFC can reduce attentional bias to intergroup threat.