Development of ACC-amygdala activations in processing unattended fear.

The ability to assess facial expressions of others involves specialised brain systems important for emotional and social learning, a skill that emerges over childhood. We investigated the development of neural responses associated with implicit processing of facial emotions using magnetoencephalography in children (7-10 yrs), adolescents (12-15 yrs) and adults. The results demonstrated spatial-temporal activations in the ACC and amygdala emotion-processing systems that changed with age. The processing of emotions first engaged the earlier-developing amygdala responses and then involved the later-maturing ACC system. With increasing age there was a shift in lateralization of amygdala responses sensitive to the fearful faces. The findings contribute to a critical understanding of the development related to functional specialization of fear perception in the frontal-limbic emotion systems. The present study offers critical insights into the developmentally time-sensitive impact on the normal functioning of these brain regions.