Structural projections to the Nucleus Accumbens link to impulsive components of human risk preference

Abstract

Functional responses in the Nucleus Accumbens (NAcc) to risk- and reward-related cues can predict real-life risk-taking behavior. Since NAcc activity is driven by neurotransmission from connected brain regions, structural characteristics of tracts projecting to the NAcc may also predict risk preference. To quantify risk preference, we employed latent variables previously derived in a comprehensive, independent study examining the psychometric structure of risk preference, which yielded a general risk preference factor as well as several specific factors, including a factor capturing impulsivity. Informed by previous work, we preregistered a set of hypotheses concerning the association between different risk preference factors and the structural properties of projections from Medial Prefrontal Cortex (MPFC), Anterior Insula (AIns), Amygdala (Amy), and an inferior tract from the Ventral Tegmental Area (iVTA) to the NAcc. To test our hypotheses, we characterized tract coherence in a sample of 125 healthy human adults. As predicted, iVTA-NAcc tract coherence showed a negative correlation with a psychometric factor that captured impulsivity, confirming findings from prior research. Also as predicted, Amy-NAcc tract coherence was positively associated with the impulsivity factor. Contrary to predictions, we observed no robust associations between the general risk preference factor and NAcc projections from MPFC, AIns, or Amy. The specificity of our findings implies that impulse control as a facet of risk preference aligns more directly with neurobiological processes, whereas other factors may encompass broader, potentially strategic elements and thus exhibit less precise brain-behavior relationships. Although the exact functional mechanisms are yet to be fully understood, conNAcctomic approaches like the one presented here could pave the way for further research into the physiological foundations of risk preference and related constructs.