Functional cerebello-cortico-limbic connectivity in aggression: A resting-state 7T fMRI study in healthy volunteers

Structural and functional magnetic resonance imaging (fMRI) studies of the human brain point towards the involvement of the cerebellum in aggressive behaviour. However, the extent to which the cerebellum is part of the brain's intrinsic network subserving aggression remains unknown. To address this issue, 28 healthy volunteers aged 18-32 years underwent a 9-min resting-state 7T fMRI scan, and functional connectivity between the posterior vermis, fastigial nuclei (FN), bilateral Crus I-II of the cerebellum and the amygdala, hypothalamus, subgenual anterior cingulate cortex (sgACC), and ventromedial prefrontal cortex was examined. In addition, behavioural and self-reported indices of aggression and basal steroid hormone levels were assessed and correlated to resting-state cerebellar functional connectivity. Results demonstrated that the posterior vermis was functionally connected to the hypothalamus, centromedial amygdala (CMA), and sgACC. The FN showed functional connections with the CMA and hypothalamus. Bilateral resting-state activity of Crus I-II was significantly associated with resting-state activity of the left sgACC. Functional connectivity of the posterior vermis and FN with the hypothalamus, CMA, and left sgACC was significantly correlated with impulsivity and aggressive behaviour. Associations between cortisol and FN-hypothalamus functional connectivity and between testosterone and cerebellum-sgACC functional connectivity were observed. The findings show that the cerebellum and its connections are part of an intrinsic subcortical motivational circuit associated with aggression.