The Functional Magnetic Resonance Imaging Of First-episode Depression In Resting State And Task State

Object: Using functional magnetic resonance imaging (fMRI), we explored differences of regional brain spontaneous activity in resting state in depressed vs healthy participants. The purpose was to investigate the baseline character of neural activity in depression associated with physiological changes or affect disorder. Method: Sixteen participants diagnosed with depressive disorder according to DSM-IV and 16 controls were scanned during resting state for 5 min and 12 sec. We used a novel method based on regional homogeneity (ReHo) to detect unpredicted homodynamic responses across the whole brain on fMRI data, and then to analyze the differences of ReHo between depression and control by t-test. We used HAMD to measure the severity of depressed participants, and then explored the relationship between ReHo and HAMD. Results: Abnormal spontaneous thalamus, cerebral; occipital lobe; temporal lobe activity was found. The ReHo of left thalamus, left cerebral, occipital lobe and left temporal lobe was significantly decreased in resting state in depression compared to healthy control. The ReHo was not significantly correlated with the total score of HAMD in depression. But the ReHo of left thalamus was correlated with sleep factor and weight factor, and the ReHo of left temporal lobe was correlated with cognitive factor and mood factor in depression. Conclusions: By using ReHo method and resting fMRI, the abnormal spontaneous activity in the left thalamus and temporal lobe was found as references for distinct brain activity signatures in first episode depression.Objective: Depression involves either enhanced processing of negative stimuli or diminished processing of positive stimuli. We used functional magnetic resonance imaging to assess brain activation in depressed vs healthy participants. The purpose was to probe the differences of neural activation associated with reactivity to negative and positive affective stimuli in patients with depressive disorder, and investigated the effects of Venlafaxine before treatment and after 8 weeks on the differently activated brain areas. Method: Patients with depressive disorder (n=14) and healthy comparison subjects (n=14) were scanned on three occasions based on conventional block-design, during which positive, neutral and negative affective pictorial visual stimuli from IAPS were presented. Symptoms were evaluated at each testing occasion by HAMD, HAMA and TESS. AFNI was used to examine the fMRI data. We analyzed the different activation-character and also focused on the group-by-time interactions by SPSS according the percentage of signal-change. Results: Twelve patients were followed up successfully. According the HAMD, 91.7% patients showed a significant reduction in depressive symptoms with treatment. For positive/neutral pictures, depressed subjects exhibited less valence than did controls form effect scale rating (ESR), which also showed a significantly less activation in bilateral middle frontal gyrus, left inferior parietal lobule and more activation in amygdale and left insular. For negative/neutral pictures, depressed subjects showed more activation in the left dorsolateral prefrontal cortex, left middle frontal gyrus, right insular, left temporal cortex and right amygdale and also significantly less activation in the left inferior parietal lobule. Left thalamus showed significantly less activated either positive or negative stimuli, bilateral lobule cortex showed less activated by positive stimuli, and left lobule cortex showed only more activated by negative stimuli. Group-by-time interactions in response to the negative or positive versus neutral stimuli were found in prefrontal cortex, parietal cortex, left insular cortex and left thalamus. After treatment, activation increased in most of the different brain area at baseline in response to the positive versus neutral stimuli, and decreased in most of the different brain area at baseline in response to the negative versus neutral stimuli. Conclusions: The findings underscore the important complex activation pattern that varies for neural circuits that may be associated with biascognitive or mood processing in first episode depression, and indicate that components of this circuitry can be changed within treatment with antidepressant medication.Part III The neural dysfunction of verbal and spatial working memory in first-episode depression by functional MRI using n-back taskObject: Several neuropsychological studies have reported cognitive impairments in depressed patients compared to control subjects, especially in attention, memory and executive functions. Working memory include these psychological components. Using fMRI on working memory, we explore the abnormal neural basis associated with cognitive impairments in depression. Method: Twelve patients with depressive disorder and 12 healthy controls were tested with a verbal version and a spatial version of the n-back task during fMRI scanning. The working memory load was manipulated across the experiment (0, 2-back). FMRI data were analyzed using AFNI software. We analyzed the different activation-character by SPSS according to the percentage of signal-change. Results: We found significantly lower accuracy in performance for both the verbal version and the spatial version of the 2-back task in depression. Depressive participants showed decreased activation in middorsolateral prefrontal region and Broca's area in verbal version, especially in the left brain. Depressive participants also showed decreased activation in middorsolateral prefrontal region and superior parietal cortex in verbal version, especially in the right brain. Conclusions: These results indicate the existence of a network of prefrontal and parietal regions mediating cognitive impairments in first episode depression, in particular on attention, memory and executive functions.