A Meta-Analysis of fMRI Studies on Emotion Processing in Major Depressive Disorder

Abstract

The processing of an emotional stimulus involves a multi-step process that includes appraising and identifying a stimulus as well as producing an affective state in response. Many individuals with depressive disorders such as major depressive disorder (MDD) experience impairments related to emotion processing, likely caused by changes in the structure and function of brain regions important for emotion processing. However, the precise neural differences underlying emotion processing impairments in MDD remain unclear given conflicting findings in the neuroimaging literature. This lack of clarity has hindered the development of novel neurostimulation treatments for MDD, which require targeting of specific brain areas. In an effort to better identify specific areas of the brain to target for stimulation treatment, I conducted a meta-analysis of the functional magnetic resonance imaging (fMRI) literature to date regarding emotion processing in MDD. The meta-analysis of fMRI studies examined emotion processing in healthy controls and individuals with MDD using the tool GingerALE. Results showed clusters of hyperactivity in the amygdala and portions of the ventral basal ganglia, a finding that held true when limiting the analysis to only those studies that utilized negative stimuli. Additional exploratory results showed a cluster of hypoactivity in the right dorsolateral prefrontal cortex. These results help to shed light on neural changes underlying emotion processing in MDD, and may serve to inform future neurostimulation clinical trials.