Brain Structure and Individual Differences in Social Behaviors

Brain structure exhibits systematic relationships with a variety of an individual’s cognitive abilities and such relationships can be captured by voxel-based morphometry (VBM) that computes regional gray matter volume based on anatomical MRIs. This method has been successfully used to reveal brain regions that are associated with individual differences in a broad range of contexts such as perceptual performance, attention control, face recognition, introspection and personality traits (Kanai & Rees 2011). Here, we show that such relationships with brain structure extend to complex social behaviors by presenting our recent VBM studies that examined the relationships between brain structure and diverse aspects of sociocognitive behavioral traits. Specifically, we identified brain regions in which individual differences in gray matter volumes were associated with political orientation, moral sentiment, empathy and loneliness. These findings suggest that information derived from standard MRI scans could be used to extract information about an individual’s real-world and online social behavior. Unlike conventional functional neuroimaging research, our structural neuroimaging approach does not require a virtual environment that emulates social interactions and thus can directly link brain structure to real-world human behavior. As such, our approach based on individual differences in brain structure and behavior provides an important anchor point that integrates genetic and environmental factors determining diversity of human cognition and behavior. Copyright © 201 , Association for the Advancement of Artificial Intelligence (www.aaai.org). All rights reserved. Results Political orientation First, we show that individual differences in political orientation are reflected in the variability of the gray matter volume of the right amygdala and anterior cingulate cortex. Conservatives exhibit greater volume of the right amygdala, whereas liberals possess larger anterior cingulate cortex (Kanai et al., 2011). These findings extend the previous findings that motivational and psychological factors govern an individual’s political attitude by providing neuronal bases mediating the link between personality traits and political leanings.