The role of dorsolateral and ventromedial prefrontal cortex in the processing of emotional dimensions

Abstract

The ventromedial and dorsolateral prefrontal cortex are two major prefrontal regions that usually interact in serving different cognitive functions. On the other hand, these regions are also involved in cognitive processing of emotions but their contribution to emotional processing is not well-studied. In the present study, we investigated the role of these regions in three dimensions (valence, arousal and dominance) of emotional processing of stimuli via ratings of visual stimuli performed by the study participants on these dimensions. Twenty- two healthy adult participants (mean age 25.21 ± 3.84 years) were recruited and received anodal and sham transcranial direct current stimulation (tDCS) (1.5 mA, 15 min) over the dorsolateral prefrontal cortex (dlPFC) and and ventromedial prefrontal cortex (vmPFC) in three separate sessions with an at least 72-h interval. During stimulation, participants underwent an emotional task in each stimulation condition. The task included 100 visual stimuli and participants were asked to rate them with respect to valence, arousal, and dominance. Results show a significant effect of stimulation condition on different aspects of emotional processing. Specifically, anodal tDCS over the dlPFC significantly reduced valence attribution for positive pictures. In contrast, anodal tDCS over the vmPFC significantly reduced arousal ratings. Dominance ratings were not affected by the intervention. Our results suggest that the dlPFC is involved in control and regulation of valence of emotional experiences, while the vmPFC might be involved in the extinction of arousal caused by emotional stimuli. Our findings implicate dimension-specific processing of emotions by different prefrontal areas which has implications for disorders characterized by emotional disturbances such as anxiety or mood disorders.

Figure 1

(a) The SAM scales for rating stimulus valence, arousal, and dominance, in order from top to bottom; (b) a schematic diagram for the effect of the dlPFC and vmPFC on the valence and arousal based on the findings of the present study. Abbreviations: dlPFC: dorsolateral prefrontal cortex, vmPFC: ventromedial prefrontal cortex.

Figure 2

Shown are the effects of tDCS on valence, arousal and dominance of emotion ratings. Note vmPFC = ventromedial prefrontal cortex; dlPFC = dorsolateral prefrontal cortex; ns = non-significant; High emotional intensities represents positive, and low emotional intensities negative emotions for valence. * = indicates significant pairwise comparisons between stimulation conditions based on the results of post-hoc t-tests (paired, p < 0.05) n = 22; all error bars indicate Standerd Error of Mean (SEM).

Figure 3

Emotional attribution system disorders in depression and anxiety. A schematic diagram for the assumed role of arousal and valence in the psychopathology of anxiety and depression. Abbreviations: dlPFC: dorsolateral prefrontal cortex, vmPFC: ventromedial prefrontal cortex.