In search of the depressive self: extended medial prefrontal network during self-referential processing in major depression.

Major depression is associated with an excessive self-focus, a tendency to engage oneself in self-referential processing. The medial frontal gyrus (MFG) is central to self-referential processing. This study aimed to explore the neural bases of this excessive self-focus and to disambiguate the role of the MFG in the pathophysiology of major depression. We presented 15 depressed patients and 15 healthy subjects with personality traits during functional magnetic resonance imaging and asked them to judge whether each trait described them ('self' condition) or a generally desirable trait ('general' condition). Both patients and healthy subjects activated the MFG in 'self' vs 'general' condition. However, the activation of the dorsal part of the MFG and of the dorsolateral prefrontal cortex (DLPFC) in 'self' vs 'general' condition was unique to patients. Additionally, patients displayed an increased functional connectivity between the MFG, the dorsal anterior cingulate cortex and the DLPFC. These results provide evidence for an extended medial prefrontal network during self-referential processing in major depression, suggesting the involvement of a greater cognitive control.