White matter tracts alterations underpinning reward and conflict processing.

Background: Reinforcement sensitivity theory (RST) is proposed as a neurobiological system that eventually led to emotion and motivation-based constructs of personality. Traditionally segmented into the behavioral activation system (BAS) and the behavioral inhibition system (BIS), RST is commonly used to describe personality and behavior. Although there have been studies linking gray matter alterations with BIS/BAS subscales, the role of white matter (WM) alterations is yet controversial. We aimed to investigate the specific WM tracts associated with BIS/BAS scores.

Methods: 220 healthy participants (mean age = 39.14 ± 20.23, 80 (35.7 %) females) were evaluated using the BIS/BAS questionnaire from the LEMON database. Diffusion MRI connectometry (DMRI) was used to investigate the WM correlates of BIS/BAS subscales in each gender group. Multiple regression models with the covariates of age, handedness, and education were fitted to address the correlation of local connectomes with BIS/BAS components.

Results: DMRI connectometry revealed that the quantitative anisotropy (QA) value of the splenium of the corpus callosum, right cerebellum, middle cerebellar peduncle, and superior cerebellar peduncle, had a significant negative correlation with each BIS/BAS subscale. In contrast, the QA value in the body of the corpus callosum and bilateral cingulum showed a positive correlation with BIS/BAS subscales.

Conclusion: The integrity of WM in certain tracts is associated with behavioral activation and inhibition. This finding expands our knowledge of the neural networks associated with risk-taking and reward-seeking behaviors.