Targeted neuromodulation of the left dorsolateral prefrontal cortex alleviates altered affective response evaluation...

Loneliness has been suggested to be linked to increased bottom-up appraisal processes of social threat coupled with top-down emotion regulation mechanisms. We have recently found a partial confirmation for such mechanisms in our large scale study (Mąka et al., in press), thus, in this preregistered double-blind study, we tested the effects of noninvasive brain stimulation over the dorsolateral prefrontal cortex (dlPFC) on emotional response and regulation in lonely individuals. 120 individuals received active (2 mA) or sham transcranial direct current stimulation over the left or right dlPFC in separate sessions. Participants were asked to passively watch negative or neutral stimuli or to reinterpret negative stimuli to decrease their affective response. Overt behavioral responses (valence and arousal self-response) and covert physiological markers (event-related potentials) of the affective response in each group were analyzed separately for stimuli with and without social content. Active dlPFC stimulation enhanced neural modulation during the reappraisal of social stimuli, as reflected in a larger difference in late positive potential between reappraised and passively viewed negative images. However, the valence rating difference between these conditions suggested less effective reappraisal under active stimulation. Anodal stimulation of the left dlPFC selectively decreased self-reported emotional reactivity during the passive viewing of social stimuli in highly lonely individuals. However, this effect occurred without corresponding changes in ERP markers. These results confirm that loneliness may primarily impair the self-monitoring of affective responses rather than that of regulatory mechanisms. Furthermore, targeted non-invasive brain stimulation of dlPFC can alleviate loneliness-related difficulties in this domain.