Fear-related activity in the prefrontal cortex increases with age during adolescence: a preliminary fMRI study

An emerging theory of adolescent development suggests that brain maturation involves a progressive "frontalization" of function whereby the prefrontal cortex gradually assumes primary responsibility for many of the cognitive processes initially performed by more primitive subcortical and limbic structures. To test the hypothesis of developmental frontalization in emotional processing, we analyzed the correlation between age and prefrontal cortex activity in a sample of 16 healthy adolescents (nine boys; seven girls), ranging in age from 8 to 15 years, as they viewed images of fearful and happy faces while undergoing functional magnetic resonance imaging (fMRI). During fear perception, age was significantly positively correlated with greater functional activity within the prefrontal cortex, whereas no significant relationship was evident between age and activity in the amygdala. Consistent with previous gender-related findings, age was significantly correlated with bilateral prefrontal activity for the sample of females, but was only significantly related to right prefrontal activity for the males. In contrast, similar age-related correlations were not evident during the perception of happy faces. These results suggest that the maturation of threat-related emotional processing during adolescence is related to the progressive acquisition of greater functional activity within the prefrontal cortex. The hypothesis of age related decreases in amygdala activity was not supported, but may have been due to low signal-to-noise and inadequate power in the present sample to resolve subtle changes in this small structure.