Mechanism Of Interaction Between Affective And Cognitive-Control Brain Regions In Depression

Depression is a commonly-occurred mental disorder. According to WHO, it has been the fourth leading cause of death and disability, and will continue to be the second one by 2020, only second to coronary heart disease. A global research finding was announced that depression had a worse influence on people than angina episodes, arthritis, asthma and diabetes on September 8th, 2007. Therefore, studies on pathogenesis of depression have recently become one of the most important research fields.As pathogenesis of depression is complicated, so many researchers at home and abroad are engaged in the studies. The cognitive mechanism of depression is one of hot topics recently. Aron?Beck, the American psychologist, addressed that depression resulted from negative cognitive schema in 1976. And the following studies confirmed that depressed patients, as result of their negative cognitive schema, were apt to choose negative information consistent to their negative schema when processing external information, which leaded to the generation and development of depression. The bias in depressed patients might represent abnormal bottom-up responses to affectively laden stimuli, and might also represent impaired top-down cognitive control over affective responses. However, how does affective processing interact with cognitive control in depressed patients? Is mechanism of interaction between positive emotion processing and cognitive control different from that of interaction between negative emotion processing and cognitive control. The recent studies could not give complete explanations. Therefore, by the technology of behavior and fMRI, this study observed the mechanism of interaction between affective and cognitive control in normal and depressed individuals during the emotion-interference task. The results and conclusions were obtained as follows:1. The accuracies of the individuals with depressive emotion was significantly lower than that of the control group when they attended to the happy faces, suggesting that the depressive emotion had a negative influence on the processing of the positive emotional stimuli. While no significant difference on the accuracies was found between the individuals with depressive emotion and the control group when they attended to the sad faces. The accuracies of the individuals with depressive emotion, however, was both significantly lower than that of the control group when they ignored the happy and sad faces.2. The accuracies of the depressed group was significantly lower than that of the control group when they attended to the happy faces. While no significant difference on the accuracies was found between the depressed group and the control group when they attended to the sad faces. In addition, there was no significant difference on the accuracies between the depressed group and the control group when they ignored the happy and sad faces.3. The depressed group showed significantly increased activation in bilateral amygdala and right dorsolateral prefrontal cortex when they attended to the happy faces. While no significant difference on the activity in bilateral amygdala and bilateral dorsolateral prefrontal cortex was shown between the depressed group and the control group when they attended to the sad faces. And there was no significant difference on the activity in bilateral amygdala and bilateral dorsolateral prefrontal cortex between the depressed group and the control group when they ignored the happy and sad faces.4. We found a significant positive correlation between activity in right amygdala and in right dorsolateral prefrontal cortex when the depressed group, but not the control group, attended to the happy faces. And we also found a significant positive correlation between activity in bilateral amygdala and in bilateral dorsolateral prefrontal cortex when the depressed group, but not the control group, ignored the happy faces. While a significant negative correlation between activity in bilateral amygdala and in left dorsolateral prefrontal cortex was found when the control group, not the depressed group, attended to the sad faces. And a significant negative correlation between activity in right amygdala and in left dorsolateral prefrontal cortex was found when the control group, not the depressed group, ignored the sad faces. In addition, we found positive correlation not only between the score of depressive symptoms and the activity in amygdala, but also between the score of depressive symptoms and the activity in dorsolateral prefrontal cortex.5. During passive resting, a significant reciprocal interregional connectivity was found in bilateral amygdala and dorsolateral prefrontal cortex (bilateral middle frontal gyrus) in both groups. And compared to the control group, the depressed group'bilateral amygdala had connected to more cognitive-control brain regions. And we detected a significant difference for bilateral amygdala to dorsolateral prefrontal cortex (right middle frontal gyrus) connectivity between the depressed patients and controls in terms of higher connectivity in patients. Morever, we detected higher connectivity not only from left amygdala to bilateral cingulate gyrus, right middle occipital gyrus, bilateral middle temporal gyrus and left superior temporal gyrus, but also from right amygdala to right cingulate gyrus, left postcentral gyrus, left precuneus, left insula and left thalamus in them.