The goals of this study were to (i) identify genetically-associated neural networks for externalizing by examining polygenic associations with resting-state functional connectivity, and (ii) examine associations between the externalizing PS, neural networks, and behavioral phenotypes of externalizing (e.g., alcohol and substance use disorders). Based on our previous finding that the externalizing PS was associated with poorer performance on tasks of inhibitory control (Sadeh et al., 2016), we expected this PS to predict neural network resting-state connectivity and function in regions of the brain that are central to maintaining such control (e.g., inferior frontal gyrus; dorsolateral prefrontal cortex, anterior cingulate; Aron et al., 2004; Criaud and Boulinguez, 2013; Nee et al., 2007). In light of evidence that externalizing disorders are characterized by dysfunction in mesolimbic reward and emotional-salience systems (Durazzo et al., 2011; Gilman et al., 2014; Glenn and Yang, 2012; Korponay et al., 2017), we hypothesized that the externalizing PS may also moderate network resting-state connectivity and organization in ventral striatum and amygdala. Two graph properties were examined: Participation Coefficient indexes the extent to which a node is a ‘connector
