Identifying affective state via clustering of temporal variability in limbic activity and mediating role of negative emotion.

The amygdala and nucleus accumbens are associated with emotion management in humans. Emotions play a central role in conditions such as depression and anxiety, where emotional states characterize the core symptoms. Effective emotion regulation can alleviate these symptoms, which highlights the importance of amygdala and nucleus accumbens in mental health. Functional magnetic resonance imaging studies that incorporate temporal characteristics of brain regions are limited. Therefore, this study examined the association of temporal variability of the limbic region, specifically the amygdala and nucleus accumbens, with worsening depressive or anxiety states mediated by negative emotions. The study included 1,080 healthy subjects from the Human Connectome Project dataset, and nine functional networks were extracted from the limbic region using group independent component analysis. Spectral clustering was performed on the temporal variability of these networks. Two distinct clusters were found in healthy adults according to the temporal variability of limbic networks. The association of increased temporal variability of functional networks with worsening affective states, including depression and anxiety, was partially mediated by the level of anger-physical aggression. These findings indicate that temporal variability in limbic regions might impact the emotion of anger and the level of anger, in turn, influences affective states, even in healthy participants.