Neural mechanism of placebo effects and cognitive reappraisal in emotion regulation

The present study compared learning-based placebo effect and cognition-based reappraisal, to reveal the common and unique neural mechanisms between the two emotion regulations. First, the anxiety-relieving effect was tested by conducting a behavioral experiment. Next, the participants with the highest placebo or reappraisal effect were selected for the functional magnetic resonance imaging experiments. The results indicated that: (1) they both attenuated activity in the right amygdala and right insula, and (2) placebo effect activated the left subgenual cingulate whereas reappraisal activated the right dorsal prefrontal cortex (PFC) and the left inferior PFC. Our results show that learning-based placebo effect and cognition-based reappraisal have common anxiety-relieving effects. The placebo effect mainly depends on direct pathway subgenual cingulate-amygdala to regulate emotions, whereas the reappraisal may rely on both indirect pathways, such as the dorsal PFC-subgenual cingulate-amygdala, and direct pathways, such as the ventral lateral PFC-amygdala to regulate emotions.