Previously, we proposed that the mean diffusivity (MD), a measure of diffusion tensor imaging (DTI) in areas of the dopaminergic system (MDDS), is associated with motivation. In this study, we tested if and how the motivational state is associated with MD in comparison with other mood states. We also tested the associations of these mood states with multiple cognitive functions. We examined these issues in 766 right-handed healthy young adults. We employed analyses of MD and a psychological measure of the profile of mood states (POMS) as well as multiple cognitive functions. We detected associations between the higher Vigor subscale of POMS and lower MD in the right globus pallidum, right putamen to right posterior insula, right caudate body, and right thalamus, and these associations were highly specific to the Vigor subscale. Similarly, the association of the motivational state with creativity measured by divergent thinking (CMDT) was rather specific and prominent compared with that of the other mood states and cognitive functions. In conclusion, when affective states are finely divided, only the motivational state is associated with MD in the areas related to the dopaminergic system, and psychological mechanisms that had been associated with dopaminergic system (CMDT). These results suggest that these mechanisms specifically contribute to the motivational state and not to the other states, such as depression and anxiety.
Keywords: Brain structure; Dopaminergic system; Mean diffusivity; Mood state; Motivation.