Functional mapping of dynamic happy and fearful facial expression processing in adolescents

This paper assessed the neural systems involved in processing of dynamic facial expressions in adolescents. The processing of facial expressions changes as a function of age, and it is thus important to understand how healthy adolescent subjects process dynamic facial expressions prior to analyzing disease-related changes. We hypothesized that viewing of dynamic facial expressions with opposing valences (happy vs. fearful) induces differential activations and deactivations in the brain. 27 healthy adolescents (9 female, 18 male, mean age = 14.5 years; age range 11.6-17.3 years) were examined by using the ASSQ and K-SADS-PL and scanned with 1.5-T fMRI during viewing of dynamic facial expressions and mosaic control images. The stimuli activated the same areas as previously seen in dynamic facial expression in adults. Our results indicated that opposing-valence dynamic facial expressions had differential effects on many cortical structures but not on subcortical limbic structures. The mirror neuron system is activated more during viewing of fearful compared to happy expressions in bilateral inferior frontal gyrus (IFG) and superior temporal sulcus (STS) left dominantly. We also detected more deactivation in the ventral anterior cingulate gyrus (ACG), showing more automated attentional processing of fearful expressions during passive viewing. Females were found to deactivate the right frontal pole more than male adolescents during happy facial expressions, while there were no differences in fear processing between genders. No clear gender or age effects were detected. In conclusion fear induces stronger responses in attention and mirror neurons probably related to fear contagion.