Reminders of mortality decrease midcingulate activity in response to others' suffering.

Reminders of mortality influence human social cognition, but whether and how reminders of mortality affect brain activity underlying social cognition remains unclear. To test whether increasing mortality salience modulates neural responses to others' suffering, we scanned healthy adults who viewed video clips showing others in pain using functional magnetic resonance imaging. One group of participants were primed to increase mortality salience and another group were primed with negative affect in terms of fear/anxiety. We found that perceiving painful vs non-painful stimuli in the pre-priming session activated the midcingulate/dorsal medial prefrontal cortex (MCC/dMPFC), bilateral anterior insula/inferior frontal cortex, bilateral secondary somatosensory cortex and left middle temporal gyrus. However, MCC/dMPFC activity in response to perceived pain in others was significantly decreased in the post-priming session by the mortality salience priming, but was not influenced by the negative affect priming. Moreover, subjective fear of death induced by the priming procedures mediated the change in MCC/dMPFC activity across the priming procedures. Subjective fear of death also moderated the co-variation of MCC/dMPFC and left insular activity during perception of others in pain. Our findings indicate that reminders of mortality decrease neural responses to others' suffering and this effect is mediated by the subjective fear of death.