Functional Connectivity Bias of the Orbitofrontal Cortex in Drug-Free Patients with Major Depression

Background: The orbitofrontal cortex (OFC) plays a crucial role in emotion-processing circuits and should therefore also be included in models of the pathophysiology of major depression. The aim of this study was to compare the functional connectivity of the OFC during emotion processing in patients with major depression and healthy control subjects. Methods: Twenty-five untreated patients with major depression and 15 healthy control subjects were investigated using a functional magnetic resonance imaging face-matching task. Results: Dorsal anterior cingulate cortex, precuneus, and cerebellum activity showed less connectivity with the OFC in patients than in control subjects. In contrast, functional connectivity between the OFC and the right dorsolateral prefrontal cortex (DLPFC), right inferior frontal operculum, and left motor areas was increased in patients compared with healthy control subjects. Conclusions: The OFC plays a key role in the pathophysiology of major depression. The observed imbalance of OFC connectivity seems to represent a neural mechanism of the processing bias. From a neurobiological point of view, the uncoupling of precuneus and gyrus cinguli activity from the OFC might be associated with problems in the regulation of self-schemas, whereas the increased connectivity of the DLPFC to the OFC might represent a higher neural response to negative stimuli.