The right VLPFC and downregulation of social pain: A TMS study

Previous studies have demonstrated that the right ventrolateral prefrontal cortex (RVLPFC) is crucially involved in downregulating physical and social pain. However, it remains unclear whether the RVLPFC is more specific to either physical or social pain. The present study compares the role of RVLPFC in emotion regulation in physical- and social-pain conditions using repetitive transcranial magnetic stimulation (rTMS). A total of 60 healthy participants underwent active (n = 30) or sham (n = 30) rTMS over the RVLPFC. Following each TMS session, participants performed a non-reappraisal and then a reappraisal task to downregulate imagined physical or social pain evoked by pictures. Self-reported negative emotional ratings and electroencephalogram data were recorded during the emotion regulation task. Participants were then required to rate the valence and arousal of those pictures 30 min after the task. It is found that rTMS-activated RVLPFC led to reductions in subjective negative feelings and amplitudes of the late positive potential during reappraisal; however, these effects were found exclusively in the social-pain condition. Participants also reported higher positive valence for socially, compared to physically, painful pictures after 30 min of the task. Behavioral and electrophysiological evidence both supported the functional specificity of RVLPFC in regulation of social pain. The prominent delayed effect of rTMS makes it possible to consider the potential application of rTMS-VLPFC in clinical practice for social pain relief.