When opposites lead to the same: a direct comparison of explicit and implicit disgust regulation via fMRI

Cognitive reappraisal and placebo administration constitute two different approaches for modulating one's own emotional state. Whereas reappraisal is an explicit (effortful) type of self-regulation, placebo treatment initiates implicit processes of affective control. The brain mechanisms underlying these processes have not been directly compared with each other up until now; doing this enables the identification of distinct and shared neuronal features. We conducted a functional magnetic resonance imaging study with 45 women, who were presented with disgusting and neutral images in a block design, at three experimental sessions, over 3 consecutive days. They were asked to passively view the images in one session, engage in reappraisal in another, and in another session they received a placebo pill: a disgust-reducing 'anti-nausea drug'. Relative to passive viewing, both reappraisal and placebo treatment effectively reduced the experienced disgust intensity. In the placebo condition, this reduction was associated with decreased activation of the insula and the dorsolateral prefrontal cortex (DLPFC). In contrast, reappraisal induced increased activation in both regions. Furthermore, both regulation strategies were associated with opposite patterns of connectivity in a network encompassing the amygdala, the insula and the DLPFC. Only placebo administration led to a reduced coupling in this network.