Neuroimaging studies have shown differences in human adolescent functional activity in several forebrain regions. These differences are primarily observed in brain regions that encode emotional significance (e.g. the amygdala) integrate sensory and emotional information for the computation of value expectations (e.g. the orbitofrontal cortex), and play various roles in motivation, action selection, and association learning (e.g. striatum). Compared to adults, adolescents have a reduced hemodynamic response in lateral orbitofrontal cortex and increased activity in ventral striatum to rewards (Ernst et al., 2005; Galvan et al., 2006). Others have found reduced activity in right ventral striatum and right extended amygdala during reward anticipation, with no observed age-related activity differences after gain outcome (Bjork et al., 2004). In a decision-making task, adolescents had reduced right anterior cingulate and left orbitofrontal/ventrolateral PFC activation compared to adults during risky choices (Eshel et al., 2007). Adolescents also activated their ventral striatum and orbitofrontal cortex more strongly than did adults as they took greater risks during a Stoplight driving game —an effect driven by implicit peer pressure (Chein et al., 2011).
