Neurocognitive mechanisms behind emotional attention : inverse effects of anodal tDCS over the left and right DLPFC on gaze disengagement from emotional faces

Attention to relevant emotional information in the environment is an important process related to vulnerability and resilience for mood and anxiety disorders. In the present study, the effects of left and right dorsolateral prefrontal cortex (i.e., DLPFC) stimulation on attentional mechanisms of emotional processing were tested and contrasted. A sample of 54 healthy participants received 20 min of active and sham anodal transcranial direct current stimulation (i.e., tDCS) either of the left (n = 27) or of the right DLPFC (n = 27) on two separate days. The anode electrode was placed over the left or the right DLPFC, the cathode over the corresponding contra lateral supraorbital area. After each neurostimulation session, participants completed an eye-tracking task assessing direct processes of attentional engagement towards and attentional disengagement away from emotional faces (happy, disgusted, and sad expressions). Compared to sham, active tDCS over the left DLPFC led to faster gaze disengagement, whereas active tDCS over the right DLPFC led to slower gaze disengagement from emotional faces. Between-group comparisons showed that such inverse change patterns were significantly different and generalized for all types of emotion. Our findings support a lateralized role of left and right DLPFC activity in enhancing/worsening the top-down regulation of emotional attention processing. These results support the rationale of new therapies for affective disorders aimed to increase the activation of the left over the right DLPFC in combination with attentional control training, and identify specific target attention mechanisms to be trained