Brain Activation Response To Emotional Pictures In Depressive Patients With Antidepressant Treatment:an FMRI Study

Objective:To explore brain activation response to emotional pictures in depressed patients and normal controls.Methods:Eighteen unmedicated patients with major depression and eighteen normal subjects aged18-50were recruited from the First Hospital of Shanxi Medical University. An emotional task paradigm was applied during scanning of functional magnetic resonance imaging (fMRI) to compare brain activation response to emotional pictures before and after8weeks’ fluoxetine treatment. The task is based on an event-related design. Patients must judge the type of pictures (positive, neutral or negative) during scanning before and after treatment. We analysed the behavioral data using the SPSS13.0software, including the accuracy rate of pictures recognition and the average response time to different types of pictures. Analyses of imaging data included individual statistics, one sampl t-tests, independent sampl t-tests and paired t-tests, which were done using the SPM5and Xjview software.Results:1. The unmedicated depressed patients showed lower accuracy rate (0.53±0.26) of positive pictures recognition than the control group (0.71±0.18). There were no significant difference in the average response time to all kinds of pictures between groups.2. The depressed patients showed activation in the left postcentral gyrus, left inferior frontal gyrus, right insula when exposed to negative pictures. For positive stimuli, activation of the depressed patients was seen in bilateral precentral gyrus, the inferior frontal gyrus, left amygdala, and left putamen.3. For negative stimuli, the unmedicated patients showed increased activation in right precentral gyrus and decreased activation in left putamen, the medial and inferior frontal regions when compared with the control group. After8weeks’treatment, the patient group exhibited decreased activation in the left lingual gyrus, right inferior occipital gyrus and the rectus when compared to the controls.For positive stimuli, the unmedicated patients showed decreased activation in left postcentral gyrus, right precentral gyus, superior temporal gyrus, middle frontal gyrus, fusiform gyrus and the lingual gyrus relative to the controls. After treatment, the patients showed decreased activation in bilateral middle frontal gyrus, right inferior frontal gyrus, right superior temporal gyrus, left caudate, right putamen, posterior cingulate, right lingual gyrus, fusiform gyrus and right precentral gyus. 4. After antidepressant treatment, the patients showed decreased activation in left inferior temporal grus, right postcentral gyus and right precentral gyus were decreased in the patient group when seeing negative pictures.Conclusion:1. The lower accuracy rate of positive pictures recognition in the depressed patients suggests there is negative cognitive bias in depressive patients2. The unmedicated patients showed increased activation in the limbic system (insula, amygdala, putamen) when seeing positive pictures and incressed activation in dorsolateral prefrontal areas when seeing positive pictures.3. Compared with the control group, the activation of the left dorsolateral prefrontal areas decreased in unmedicated depressed patients and normalized after antidepressant treatment for negative stimuli. For positive stimuli, decreased activation in patients after treatment was seen in left caudate, right putamen and bilateral middle frontal gyrus. The left caudate, right putamen and prefrontal regions may be related to mechanism of antidepressant treatment.