Brain imaging, genetics and emotion.

This paper reviews the published evidence on genetically driven variation in neurotransmitter function and brain circuits involved in emotion. Several studies point to a role of the serotonin transporter promoter polymorphism in amygdala activation during emotion perception. We also discuss other polymorphisms (e.g. the COMT val158met polymorphism, tryptophan hydroxylase-2 -703 G/T) and putative effects on affective processing in cortical and limbic regions. A different line of research concerns studies with genetic disorders. Although at a less fine-grained level, studies with individuals with aneuploidies of the X chromosome (Turner syndrome and Klinefelter syndrome), who display impairments in emotion processing, have resulted in new insights and hypotheses with regard to X chromosomal influences on brain systems supporting cognition and emotion. These have also implicated a key role for the amygdala. Integration of the emerging evidence, suggests that the study of polymorphisms using brain imaging can potentially elucidate biological pathways and mechanisms contributing to individual differences in brain circuits that may bias behavior and affect risk for psychiatric illness.