Dissociable ventral and dorsal sensorimotor functional circuits linking the hypomanic personality traits to aggression via behavioral inhibition system

Hypomanic personality traits (HPT) are susceptibility markers for psychiatric disorders, particularly bipolar disorder, and are strongly associated with aggressive behaviors. However, the neuropsychological mechanisms underlying this association remain unclear. This study utilized psychometric network analysis and <i>Inter-Subject Representation Similarity Analysis</i> (IS-RSA) to explore the neuropsychological circuits that link HPT to aggression in a large non-clinical population. Psychometric network analysis (n = 716) identified two key nodes: the Behavioral Inhibition System (BIS) and mood volatility, a core dimension of HPT. We observed a positive correlation between mood volatility and aggression, with BIS serving as a mediating factor. Task-based functional imaging (n = 53) further revealed a double dissociation between the dorsal (dSMC) and ventral (vSMC) sensorimotor cortices to HPT, specifically during the processing of reward magnitude and delay in a delayed reward paradigm. Functional patterns within these regions mediated the relationship between individual differences in mood volatility and aggression, with BIS acting as a mediator through parallel pathways. Resting-state functional imaging (n = 505) replicated this functional segregation and revealed distinct integrative patterns: the dSMC was functionally connected to the frontoparietal network (FPN) and the vSMC to the sensorimotor network (SMN). These circuits collectively mediated the associations among mood volatility, aggression, and BIS. These findings highlight the critical role of sensorimotor circuits and BIS in understanding the neuropsychological pathways linking HPT-related mood volatility to aggression.