关键词: 实时功能磁共振成像神经反馈, rtfMRI-NF, 情绪调节, 抑郁症, 神经机制

Abstract: Major depressive disorder (MDD) is characterized by impaired emotion regulation. Real-time functional magnetic resonance imaging neurofeedback（rtfMRI-NF）offers a non-invasive technique to train participates to regulate activation of emotion regulation networks. During the scanning, subjects are instructed to regulate their emotions by upregulating or downregulating the activity of the target brain regions or networks. The neural mechanism of successful emotion regulation with rtfMRI-NF in MDD still remains unclear. This study provides a literature review of advantages and limitations of rtfMRI-NF, as well as results of studies using rtfMRI-NF for emotion regulation enhancement from various target brain areas in MDD. The results have shown that rtfMRI-NF can improve emotion regulation ability and reduce depressive symptom. Moreover, during and after intervene within one or several fMRI sessions, MDD patients are able to voluntarily control the activity of their target brain areas, including the amygdala, anterior insula, anterior cingulate cortex and several subregions in PFC. Furthermore, most rtfMRI-NF intervention studies also reported that enhancements of functional connectivity between target regions and other emotion-related brain regions, which might be the neural mechanism of regulating emotion successfully with rtfMRI-NF in MDD. In most studies, participants are required to increase activation of target area by recalling positive memory. Although results have shown that participants finally can control activation of target area by themselves without feedback. However, less studies reported participants’ depressive symptom during follow-up, which is important to the assessment of intervention effect. Another core symptom of MDD is anhedonia, which is caused by the functional or structural abnormalities in ventral striatum. So far, only few rtfMRI-NF intervention studies have taken ventral striatum as a target region to normalize the obvious anhedonia of MDD. Hence, using the brain network activation or connection as neural feedback information might be another effective way to strengthen the ability of emotional regulation. Actually, only a few studies provided feedback of functional connectivity among several regions to help participants to regulate brain activation. Additionally, cognitive deficits of MDD also increasingly attract more attention. Existing studies applying rtfMRI-NF intervention in MDD patients were mainly focused on emotion self-regulation training, only few evaluated cognitive performances after rtfMRI-NF training or directly improved cognitive dysfunction using rtfMRI-NF in MDD. Considering that the prefrontal cortex is a key substrate for both emotional and cognitive control, training MDD to regulate PFC may be helpful not only to enhance emotion regulation ability but also to normalize cognitive dysfunction after intervention. Further clinical researches are needed to explore the neural mechanism of NF effect on the relief of symptom in emotional and cognitive domains of depressive disorder. Alternatively, studies with aim to enhance emotion regulation ability in MDD patients can also include assessments of cognitive performances. Given that the achievement of self-regulation with rtfMRI-NF intervention might be the increased connections among several regions, further studies could select more functional-organized areas together as target regions instead of a single one. In conclusion, the rtfMRI-NF might be another promising clinical intervention, which can robustly decrease the depressive symptoms of patients.

Key words: real-time functional magnetic resonance imaging neurofeedback, rtfMRI-NF, mood regulation, major depression disorder, neural mechanism