A Brain Model of Disturbed Self-Appraisal in Depression

A disturbed sense of self is a core feature of depression. The medial prefrontal cortex, which has a central role in self-appraisal processes, is often implicated in the illness, although it remains unclear how functional alterations of the region contribute to the observed disturbances. The aim of this study was to clarify the role of the medial prefrontal cortex in self-appraisal processes in depression.

The authors applied a recently developed dynamic network model of self-directed cognition to functional MRI data from 71 adolescents and young adults with moderate to severe major depressive disorder, none of whom were being treated with medication, and 88 healthy control participants. Bayesian model averaging was used to determine parameter estimates for the dynamic causal models, which were compared between groups.

While self-directed cognitive processes in the depression group were shown to rely on the same dynamic network as in the healthy control group, the medial prefrontal cortex had a "hyperregulatory" effect on the posterior cingulate cortex in the depressed group, with self-appraisal causing significantly more negative modulation of connectivity between the medial prefrontal cortex and the posterior cingulate cortex than in the control group (odds ratio=0.54, 95% CI=0.38, 0.77). This parameter was significantly inversely related with a depression factor related to poor concentration and inner tension (r=-0.32; 95% CI=-0.51, -0.08).

The exaggerated influence of the medial prefrontal cortex on the posterior cingulate cortex in depression is a neural correlate of the disturbed self-appraisal that is characteristic of the illness.