Superior frontal gyrus and middle temporal gyrus connectivity mediates the relationship between neuroticism and thought suppression

Thought suppression, which is defined as an effort "not to think about" a particular thought, is essential to maintain good mental health. Despite previous functional imaging studies on thought suppression and related functional activity, the neural basis of thought suppression in individual difference is still unclear. Many studies have focused on the relationship between neuroticism and thought suppression; however, the neural basis of this relationship is not well known. Thus, in the present study, we investigated the neural basis of thought suppression and further explored the neural mechanisms underlying the relationship between neuroticism and thought suppression. The first step was to use voxel-based morphometry (VBM) to investigate the neuroanatomical basis of thought suppression in healthy subjects. We found a significant positive correlation between thought suppression and the gray matter volume (GMV) of the right superior frontal gyrus (SFG). The second step was to use resting-state functional connectivity (rsFC) to investigate the neural functional basis of thought suppression. The results showed that thought suppression was positively correlated with rsFC between the right SFG and the left middle temporal gyrus (MTG). Interestingly, the relationship between neuroticism and thought suppression was mediated by the strength of rsFC between the right SFG and the left MTG. The results suggest that better ability to suppress unwanted intrusive thoughts is supported by greater GMV of the right SFG and stronger functional connectivity between the SFG and MTG. They also indicate that weak rsFC between the SFG and MTG can partly explain the negative association between neuroticism and thought suppression.