Ventromedial prefrontal cortex shields value computations from bodily arousal in decision making
Emotional reactions to norm violations influence how people trade-off selfish interests against social norms, but it remains unknown which brain regions causally contribute to integrating physiological arousal associated with norm violations into the decision process. Here, we provide evidence that the ventromedial prefrontal cortex (vmPFC) causally contributes to decoupling value computations in normative choice from physiological arousal. Excitatory brain stimulation over the vmPFC reduced aversion to disadvantageous inequality in an Ultimatum game and increased post-decision confidence after acceptance of unfair monetary splits. Physiological arousal as measured via heart rate changes was increased in response to splits perceived as unfair. Enhancing vmPFC excitability reduced the sensitivity to unfairness not by directly inhibiting physiological arousal but by blocking its influence on the decision process. This suggests that vmPFC causally moderates how physiological responses to norm violations affect trade-offs between self-interests and norm considerations, highlighting its key role for integrating emotional and cognitive processes in decision making. Significance statementEmotions like anger about the violation of social norms are associated with physiological arousal, and the interoceptive awareness of this arousal is thought to influence decision making. Here, we identify the neural mechanism that causally mediates the influence of physiological arousal on the decision process. Increasing the excitability of the ventromedial prefrontal cortex strengthened selfish interests over fairness considerations in social interactions via decoupling the decision process from unfairness-evoked arousal. This provides a neuroscientific explanation for how physiological arousal influences social decisions and suggests that the role of the ventromedial prefrontal cortex for the interaction between emotion and cognition in decision making is based on interoception rather than emotion regulation.