Toward a Mechanistic Understanding of How Variation in the Oxytocin Receptor Gene Shapes Individual Differences in Brain and Social Behavior

As humans, we display remarkable variation in our preference to seek and maintain social relationships, our capacity to recognize others’ thoughts and emotions, and our willingness to attend to the needs of others. Decades of research have shown that individual differences in human social cognition and behavior are moderately heritable; however, the molecular pathways underpinning these differences remain largely unknown. Understanding the causal mechanisms linking genetic variation to social behavior is one of the central challenges of formulating a comprehensive theory for the social neurosciences. This challenge is compounded by the fact that genes do not code for behavior directly, but rather govern the assembly of molecular products that shape and organize the neural processes through which behavior is expressed. Advances in methods to quantify affective, cognitive, and behavioral systems have supplied researchers with innovative tools to buttress measurement of social phenotypes with the psychological processes that give rise to them. Eye-tracking systems record precise visual scanning patterns of social engagement. Experimental economic tasks quantify abstract concepts such as trust, spite, and jealousy using validated, transparent, and incentivized paradigms. Also, neuroimaging studies characterize the activation and connectivity of circuits underlying social and affective processing. Armed with these tools and many others, behavioral geneticists have begun to delineate the intermediary processes by which variability in genes impacts human social functioning. Nevertheless, a critical link at the outset of this causal chain—from genetic variation to transcriptional regulation in the brain—has been lacking. In this issue of Biological Psychiatry, blending genomics with neuroanatomic data, King et al. ( ) use the prairie vole model system to investigate the link between genetic variation in the oxytocin receptor gene and individual differences in both oxytocin receptor expression and protein density in brain.