| Negative emotion experiences of anxiety and depression have vital influences on individual's physical and mental health,social behavior,and even cognitive function.They are the two most typical typical negative emotional experiences in the fields of psychology and cognitive neuroscience.A series of studies by Clark and Watson et al.showed that anxiety,depression,and other related psychological variables(such as perceptual pressure,etc.)are often highly correlated with each other.According to them,they believe that anxiety and depression may be jointly affected by a potential trait factor,which is regarded as negative affect.This study follows the hypothesis that all negative emotion experiences related to anxiety and depression are collectively referred to as negative affect.In the field of neuroimaging,a large number of studies on anxiety and depression also provided evidences for this negative affect theory,and found that although there are differences in neurological mechanisms between anxiety and depression,individuals with high level of anxiety and depression or those with related mood disorders always,show enhanced functional connections of some subcortical structures(such as the amygdala and dorsal striatum),along with some relatively weak connections of prefrontal cortex(such as the ventral medial prefrontal and dorsolateral prefrontal cortex).The former may reflect the hyper-activation of bottom-up driving effects,while the latter may reflect the relatively weaker top-down emotion regulation ability.Negative affect is not only a trait variable but also exist state-related feature at the same time.The trait negative affect is mainly reflected in:(1)it is greatly influenced by heredity and early environment,as well as,high correlation with personality trait of neuroticism,(2)its stability and continuity,reflected in that individuals with high negative affect are more likely to report discomfort in different situations.The state negative affect is mainly reflected in:(1)the relevant emotional experience will change along with the variation of individual status,and fluctuate around the baseline level(trait level);(2)negative affect can be clearly reflected in the physiological indicators and behavioral performance.Since the trait is always contained within the state(sharing a large part of the variation),it is difficult to distinguish the above two characteristics by means of psychological measurement alone.However,considering trait factors may be the root cause of various related emotional disorders,it is particularly important to separate the trait factors out of the state ones.On the other hand,studies have found that individuals' resting state functional connectivity(rs-FC)pattern can both exhibit trait and state features,claiming that,although rs-FC pattern remains largely stable,it will also undergoes structural adjustments as individual states change.Based on this finding,the separation between trait and state of negative affect by means of neuroimaging may can be a new idea.The core objectives of this study include the following aspects:(1)verify the negative affect theory(negative affect is the potential variable that affect anxiety and depression),and related neural mechanism revealed by previous studies,as well as,detect the trait and state features of negative affect;(2)based on the hypothesis that trait-specific negative affect may correspond to certain relatively stable rs-FCs,while state negative affect may be related to certain relatively variable rs-FCs,the current study try to separate the trait and state features of negative affect.Study 1: first,study includes multiple anxiety and depression-related psychological measures in the test-retest samples with long time interval,and analyse the correlation between these measures at the same time point and at different time points;second,the standardized principal component score of these measures is regarded as a measure of negative affect,then its correlation to rs-FCs is analysed;finally,applying multivariate analysis(support vector regression),study explores whether the feature of rs-FCs can effectively predict the negative affect level of individuals.The results show that:(1)each of these variables remains moderately correlation over a longer time interval,and there are also significant correlations between each other(these significant correlations even exist between different time points);(2)negative affect level(the principal component score)is mainly related to rs-FCs involving the putamen,but negatively related to rs-FCs involving the ventromedial prefrontal cortex(vm PFC)and the dorsolateral prefrontal cortex(dl PFC).Meanwhile,the feature of relevant rs-FCs can effectively predict negative affect level of individuals.Study 2: first,study applies graph theory to conduct variability detection,and divides the rs-FCs into relatively stable and relatively variable components by using the median of the group level variability;second,try to apply multivariate analysis to explore whether the trait and state negative affects can be reflected in different components of rs-FCs(taking neuroticism,a stable personality trait which showed strongly relation to negative affect,as the representative of trait negative affect;while,the difference of principal component scores between different time points as the index responding to state negative affect).The results show that:(1)rs-FCs,which correlate to negative affect level and are relatively stable,mainly derive from connections involving the putamen and vm PFC,whereas relatively variable ones are mainly from connections involving the association system(especially the dl PFC);(2)relatively variable connections are only sensitive to state negative affect(their difference values between time points can predict the difference value of negative affect),whereas relatively stable connections are only sensitive to trait negative affect(related rs-FCs can predict neuroticism level of individuals).In summary,first of all,study results support negative affect theory(negative affect is the overlap of anxiety and depression),and reveal the trait and state features of negative affect.Besides,to a large extent,results verify the findings of previous neuroimaging studies on negative affect.Then,it is showed that the pattern of specific rs-FCs can be used as an effective indicator to detect negative affect level of individuals.Furthermore,results suggest that the bottom-up driving of negative stimuli(mainly related tothe rs-FCs of the putamen in the dorsal striatum)may be a key fact of trait negative affect.The hyper driving effect may lead to high trait negative affect.On the other hand,relatively weaker top-down emotion regulation abilities may also relate to the level of high negative affect.The emotion regulation abilities are reflected in two aspects: the "hot" regulation mechanism without conscious participation,and the "cold" regulation mechanism with conscious participation.The former,which is dominated by the vm PFC,associates with trait negative affect,may playing a role as the implicit emotion regulation mechanism;while the latter,which is dominated by the dl PFC,is related to state negative affect,may involving certain advanced cognitive processes functions(such as rationalization,etc.)as the compensatory mechanism as negative stimulus increase. |
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