Converging evidence from functional neuroimaging studies of chronic marijuana using adolescents reveal deviations from the typical neural networks subserving these cognitive tasks. Brain response patterns in marijuana-using teens consistently indicate increased utilization of alternate brain networks. One of the first studies to demonstrate this profile administered a spatial working memory task to 15-17 year-old MJ+ALC-using teens. Relative to controls, users demonstrated increased blood oxygen level dependent (BOLD) response in right superior frontal cortices yet decreased activation in right inferior frontal and temporal regions (Schweinsburg et al., 2005). Tasks of verbal working memory (Jacobsen et al., 2007) and response inhibition (Tapert et al., 2007) elicit similar findings in marijuana-using teens, where greater activation was seen in frontal, parietal, and mid-cingulate regions as compared to performance-matched controls. Together, these data coincide with patterns of altered brain functioning found in marijuana-using adults (Eldreth et al., 2004; Kanayama et al., 2004), suggesting that users are less able to recruit the typical neural networks underlying complex cognitive functions and may require more neural resources to perform adequately. It is possible that diminutions in white matter
