The goal of this study was to observe the differences in brain activation under negative emotional picture stimuli in drug-naïve female patients with a first major depressive episode, comparing patients with and without stressful life experiences prior to the onset of depression. Using a 3.0 T magnetic resonance imaging (MRI) system, 18 patients who experienced stressful life events (SLEs) and 15 patients who did not experience SLEs were scanned under a task-fMRI paradigm designed to distinguish between negative and neutral neural responses to visual stimuli. SPM 8.0 software was used to process the fMRI data; the significantly activated brain regions were recorded and organized in the Montreal Neurological Institute (MNI) standard space. Upon stimulation with negative emotional pictures, depressed patients who had experienced SLEs showed significantly increased activation of the bilateral superior temporal gyrus, left middle temporal gyrus, left middle occipital gyrus, left medial frontal gyrus, right inferior frontal gyrus, bilateral precentral gyrus, bilateral postcentral gyrus, bilateral middle frontal gyrus, right precuneus, left paracentral lobule, bilateral thalamus, bilateral hippocampus, and left cerebellum when compared with depressed patients who did not experience SLEs.The brain regions that showed increased activation in depressed patients who experienced SLEs were primarily located in the neural circuits of the emotion processing system; this result likely indicates that these patients may have an increased negative cognitive bias in the perception, experience, and memory of negative emotional events, as well as their response to those events.
Keywords: First major depressive episode; Functional magnetic resonance imaging; Stressful life events.