Transcranial Electrical Stimulation over Dorsolateral Prefrontal Cortex Modulates Processing of Social Cognitive and Affective Information

Abstract

Recent neurofunctional studies suggested that lateral prefrontal cortex is a domain-general cognitive control area modulating computation of social information. Neuropsychological evidence reported dissociations between cognitive and affective components of social cognition. Here, we tested whether performance on social cognitive and affective tasks can be modulated by transcranial direct current stimulation (tDCS) over dorsolateral prefrontal cortex (DLPFC). To this aim, we compared the effects of tDCS on explicit recognition of emotional facial expressions (affective task), and on one cognitive task assessing the ability to adopt another person's visual perspective. In a randomized, cross-over design, male and female healthy participants performed the two experimental tasks after bi-hemispheric tDCS (sham, left anodal/right cathodal, and right anodal/left cathodal) applied over DLPFC. Results showed that only in male participants explicit recognition of fearful facial expressions was significantly faster after anodal right/cathodal left stimulation with respect to anodal left/cathodal right and sham stimulations. In the visual perspective taking task, instead, anodal right/cathodal left stimulation negatively affected both male and female participants' tendency to adopt another's point of view. These findings demonstrated that concurrent facilitation of right and inhibition of left lateral prefrontal cortex can speed-up males' responses to threatening faces whereas it interferes with the ability to adopt another's viewpoint independently from gender. Thus, stimulation of cognitive control areas can lead to different effects on social cognitive skills depending on the affective vs. cognitive nature of the task, and on the gender-related differences in neural organization of emotion processing.

Fig 1. Recognition of emotional facial expressions.

RTs are plotted against the six emotions (disgust, happiness, fear, anger, surprise and sadness); bars represent SEM. Significant comparisons are highlighted by an asterisk (p < .05).

Fig 2. Recognition of emotional facial expressions.

RTs plotted against the three stimulation conditions (anodal F3/cathodal F4, anodal F4/cathodal F3 and sham) and the six emotions (disgust, happiness, fear, anger, surprise and sadness), separately in males and females. Bars represent SEM. * Significant at p < .05.

Fig 3. Visual Perspective Taking.

Mean proportion of altercentric responses (upper panel; values on y-axis are degrees: 90 degrees correspond to 100% of altercentric responses) and RTs on altercentric responses (lower panel) plotted against the three stimulation conditions (anodal F3/cathodal F4, anodal F4/cathodal F3 and sham), separately for no-action and yes-action conditions. Bars represent SEM. *The number of altercentric responses in the anodal F4/cathodal F3 stimulation for yes-action stimuli was significantly lower with respect to no-action stimuli in the same condition (p < .001), and with respect to yes-action stimuli in the other stimulation conditions (both p > .002).