No abstract

Happiness refers to people's cognitive and affective evaluation of their life. Why are some people happier than others? One reason might be that unhappy people are prone to ruminate more than happy people. The default mode network (DMN) is normally active during rest and is implicated in rumination. We hypothesized that unhappiness may be associated with increased default-mode functional connectivity during rest, including the medial prefrontal cortex (MPFC), posterior cingulate cortex (PCC) and inferior parietal lobule (IPL). The hyperconnectivity of these areas may be associated with higher levels of rumination. One hundred forty-eight healthy participants underwent a resting-state fMRI scan. A group-independent component analysis identified the DMNs. Results indicated increased functional connectivity in the DMN was associated with lower levels of happiness. Specifically, relative to happy people, unhappy people exhibited greater functional connectivity in the anterior medial cortex (bilateral MPFC), posterior medial cortex regions (bilateral PCC) and posterior parietal cortex (left IPL). Moreover, the increased functional connectivity of the MPFC, PCC and IPL, correlated positively with the inclination to ruminate. These results highlight the important role of the DMN in the neural correlates of happiness, and suggest that rumination may play an important role in people's perceived happiness.

Research has indicated that highly trait-anxious (HTA) individuals exhibit a specific deficit in filtering threat-related distractors from visual-spatial working memory (WM). Prior demonstrations of impaired inhibition control in HTA individuals have mainly focused on tasks that required the inhibition of prepotent response tendencies. Studies on the suppression of emotionally neutral distractors from WM in trait anxiety have also been minimal. In this article, we present a study on the manifestation of general inefficient filtering of neutral distractors during visual-spatial WM maintenance stages in HTA individuals. Female participants performed a visual-spatial WM task while event-related potentials were recorded. They were made to remember the orientations of red rectangles within half of the screen and to ignore all salient green rectangles. As predicted, no significant main effect of group and no interaction between group and condition were found in the N2pc component, suggesting that group differences did not manifest in the initial process of object individuation. During the subsequent WM maintenance phase, HTA individuals were highly inefficient at filtering the irrelevant items from WM, as reflected not only by parallel late contralateral delay activity (CDA; 450 to 900 ms) amplitudes for the distractor condition and the four red items, but also by a smaller filtering efficiency score in the HTA group than in the low-trait-anxiety group. Extending previous studies, our findings verify a general filtering impairment in HTA individuals for task-irrelevant salient distractors during a WM maintenance phase.