Neuroimaging studies of serotonin gene polymorphisms: exploring the interplay of genes, brain, and behavior.

Because of the unique ability it provides to investigate information processing at the level of neural systems, functional neuroimaging is a powerful tool to explore the relationship between genes, brain, and behavior. Recently, functional neuroimaging has provided dramatic illustrations of how a promoter polymorphism in the human serotonin transporter gene, which has been weakly related to several dimensions of emotional behaviors (such as neuroticism and anxiety traits), is strongly related to the engagement of neural systems--namely, the amygdala and subgenual prefrontal cortex, subserving emotional information processing. This review will outline the experimental strategy by which these genetic effects on brain function have been explored and highlight the effectiveness of this strategy to delineate biological pathways and mechanisms contributing to the emergence of individual differences in brain function that potentially bias behavior and risk for psychiatric illness.