Background: As children mature, they become increasingly independent and less reliant on caregiver support. Changes in brain systems are likely to stimulate and guide this process. One mechanistic hypothesis suggests that changes in neural systems that process reward and threat support the increase in exploratory behavior observed in the transition to adolescence. This study examines the basic tenets of this hypothesis by performing functional magnetic resonance imaging (fMRI) during well-established reward and threat processing tasks in 40 children and adolescents, aged 9-15 years.
Method: fMRI responses in the striatum and amygdala are fit to a model predicting that striatal reward and amygdala threat-responses will be unrelated in younger participants (aged 9-12 years), while older participants (aged 13-15 years) will differentially engage these structures.
Results: Our data are consistent with this model. Activity in the striatum and amygdala are comparable in younger children, but in older children, they are inversely related; those more responsive to reward show a reduced threat-response. Analyses testing age as a continuous variable yield consistent results. In addition, the proportion of threat to reward-response relates to self-reported approach behavior in older but not younger youth, exposing behavioral relevance in the relative level of activity in these structures.
Conclusions: Results are consistent with the notion that both individual and developmental differences drive reward-seeking behavior in adolescence. While these response patterns may serve adaptive functions in the shift to independence, skew in these systems may relate to increased rates of emotional psychopathology and risk-taking observed in adolescence.
Keywords: Children; functional magnetic resonance imaging; reward; threat; triadic model.