The cerebellum as a moderator of negative bias of facial expression processing in depressive patients

Abstract

• Negative bias (NB) in emotion processing is an important aspect of MDD. • Neural basis of NB in facial expression processing in MDD was assessed. • Higher activation in posterior cerebellum was found to relate to higher NB in MDD. • Higher activation in the same area was related to a lower NB in the HC group. • This area might mediate biasing emotion processing by reflecting self-mood. Negative bias—a mood-congruent bias in emotion processing—is an important aspect of major depressive disorder (MDD), and such a bias in facial expression recognition has a significant effect on patients’ social lives. Neuroscience research shows abnormal activity in emotion-processing systems regarding facial expressions in MDD. However, the neural basis of negative bias in facial expression processing has not been explored directly. Sixteen patients with MDD and twenty-three healthy controls (HC) who underwent an fMRI scan during an explicit facial emotion task with happy to sad faces were selected. We identified brain areas in which the MDD and HC groups showed different correlations between the behavioral negative bias scores and functional activities. Behavioral data confirmed the existence of a higher negative bias in the MDD group. Regarding the relationship with neural activity, higher activity of happy faces in the posterior cerebellum was related to a higher negative bias in the MDD group, but lower negative bias in the HC group. The sample size was small, and the possible effects of medication were not controlled for in this study. We confirmed a negative bias in the recognition of facial expressions in patients with MDD. fMRI data suggest the cerebellum as a moderator of facial emotion processing, which biases the recognition of facial expressions toward their own mood.