Positive Amygdala-Inferior Frontal Gyrus Coupling During Up-regulate Of Positive Emotion

Each of us has a variety of emotions, and each emotion will have different effects on us. It could give us courage, confidence and strength, but also could make us impulse, weakness, depression, sometimes it can even led us to violation of moral and legal norms. Therefore, we need to adjust and control our own emotions, and that is called emotion regulation. Emotion regulation refers to the processes by which individuals influence which emotions they have, when they have them, and how they experience and express these emotions. A Good ability to regulate emotion help individuals to maintain a good mood or change the bad mood. The existing research of emotion regulation mostly confined to negative emotion regulation, while there has been little study of positive emotion regulation. But positive emotion regulation is as important as negative emotion regulation, it should be investigated by researchers. In the past few years, with the rise of positive psychology, researchers began to focusing on positive emotion regulation. We have found that the behavior, physiological and neurological of emotion regulation to be varying consistently with the direction of up or down regulate of emotion in the past studies. However, whether the results would also appear in positive emotion regulation is still unknown.Cognitive reappraisal is an adaptive emotion regulation strategies, individuals can use it to get a new understanding or appraise of the emotional event. Cognitive reappraisal occurred prior to the final produce of emotions, it belongs to Antecedent-focused emotion regulation strategies. The essence of reappraisal is the process of rationalize the current emotional events, it is a healthy emotion regulation strategy compared to other emotional regulation strategies.The present study use a comprehensive method to investigated positive emotion regulation through behavioral, electrical physiology and neuroimaging experiments. It is consist of three experiments, from experiment 1 we investigate the variety of subjective emotional arousal, from experiment 2 the variety of zEMG(zygomatic electromyography, zEMG) and fMRI data from experiment 3. We found a significantly increased subjective emotional arousal in experiment 1 when subjects up regulate their positive emotions. We did not find a significant down regulate effect through the score in down regulate condition is less than that of the maintain condition. In Experiment 2, we analyse the data of zEMG and found a significant up regulate effect but still not a down regulate one, which coherent with the results of experiment 1. In experiment 3, we pick the bilateral amygdala as the ROI(Region of Interest,) region, we found the percent signal change of amygdala is significantly higher in up regulate condition than maintain condition in ROI analyse. We also found a higher percent signal change in down regulate condition than the up regulate condition. The results revealed more regions to be activated in up regulate condition than down regulate condition such as bilateral rACC and dlPFC. We did not find any regions which is more activated in down regulate condition than the up regulate condition. Further psychophysiological interaction(PPI) analysis showed that, compared to maintain condition, when increasing positive emotions the bilateral amygdala and the left inferior frontal gyrus showed a positive coupling, there is no regions coupled with amygdala when decreasing positive emotions.Based on the above three experiments, it is not difficult to find that when up regulate the positive emotions, the subjective emotional arousal, zEMG and amygdala percent signal change are increased compared to maintain condition, but the indicators did not exhibit significant falls compared to maintain in down regulate condition. So there is a notable up regulate effect of positive emotion but not a down regulate one. PPI analysis showed a positive coupling between bilateral amygdala and left inferior frontal gyrus in up-regulate condition, but no coupling in down regulate condition. This results partly explains the reason why there is a notable up regulate effect of positive emotion regulation, because the inferior frontal gyrus plays a top-down regulation of the amygdala. Three experiments revealed consistently that subjects have the ability to increase their positive emotions but lack the capacity to down regulate it. From the perspective of evolution, this may because the natural instincts of people which prefer to draw on advantages but avoid disadvantages, people are always chasing for better circumstance instead of a worse one. Specific to this investigation, people would be more likely and used to up regulate their positive emotion rather than down regulate it.