Positive emotionality is associated with baseline metabolism in orbitofrontal cortex and in regions of the default network

Abstract

Positive Emotionality (personality construct of well being, achievement/motivation, social and closeness) has been associated with striatal dopamine D2 receptor availability in healthy controls. Since striatal D2 receptors modulate activity in orbitofrontal cortex and cingulate (brain regions that process natural and drug rewards) we hypothesized that these regions underlie positive emotionality. To test this we assessed the correlation between baseline brain glucose metabolism (measured with positron emission tomography and [18F]fluoro-deoxyglucose) and scores on Positive Emotionality (obtained from the Multidimensional Personality Questionnaire or MPQ) in healthy controls (n=47). SPM analyses revealed that Positive Emotionality was positively correlated (pc<0.05, voxel corrected) with metabolism in various cortical regions that included orbitofrontal (BA 11, 47) and cingulate (BA 23, 32) and other frontal (BA 10, 9), parietal (precuneus, BA 40) and temporal (BA 20, 21) regions that overlap with the brain's default mode network. Correlations with the other two main MPQ personality dimensions (Negative Emotionality and Constraint) were not significant (SPM pc<0.05). Our results corroborate an involvement of orbitofrontal and cingulate regions in positive emotionality, which is considered a trait that protects against substance use disorders. Since dysfunction of orbitofrontal cortex and cingulate is a hallmark of addiction these findings support a common neural basis underlying protective personality factors and brain dysfunction underlying substance use disorders. In addition we also uncovered an association between Positive Emotionality and baseline metabolism in regions from the default mode network, which suggests that Positive Emotionality may relate to global cortical processes that are active during resting conditions (introspection, mind wandering).