The neural correlates of personality traits: Microstructure of white matter and macrostructure of gray matter using MRI

Understanding the neural correlates of personality traits is an important endeavor in psychological research. It provides information regarding the neural systems that underlie individual differences in experiencing positive and negative affect, as well as offers insights into the complexities of the neural bases of psychopathology. General consensus among personologists and neuroscientists alike is that two dissociable neural systems support positive and negative affect, which lead to the expression of extraversion and neuroticism respectively. This study sought to identify the neural components of these two dissociable systems using magnetic resonance imaging. Both gray matter macrostructure (temporal and prefrontal regions) and white matter microstructure (frontotemporal tracts) were quantified and subsequently correlated with positive and negative affect, extraversion, and neuroticism in a healthy young adult sample. Evidence for two dissociable systems was found. Specifically, more intact white matter tracts in the left hemisphere correlated with greater extraversion and reduced right prefrontal gray matter volume correlated with greater positive affect, suggesting a left-sided asymmetry is associated with these traits. By contrast, greater right prefrontal volume correlated with greater neuroticism suggesting a right-sided asymmetry is associated with this trait. A less lateralized pattern was found for negative affect; both left and right prefrontal volume was positively correlated with this trait as well as positive correlations with left and right amygdala. These findings provide more evidence for a lateralized neural pattern associated with neuroticism and extraversion. The current study will help inform future studies investigating the relationship between personality and psychopathology.