Dynamic developmental signatures of facial expression processing differ by emotion.

Facial expressions are critical social cues for deciphering others' emotional states and intentions. While the neural architecture supporting emotional face processing is well established, few studies have examined the developmental trajectory of the underlying oscillatory dynamics. Using magnetoencephalography in a large typically-developing sample (6-17 years-old), we quantified neural oscillations during gender judgments of angry, happy, and neutral faces. Alpha/beta responses to neutral faces increased with age in the posterior superior temporal cortices and decreased in the prefrontal cortex, indicating a shift toward posterior processing. Gamma oscillations increased with age for angry and neutral faces in the temporoparietal junction and fusiform, suggesting enhanced specialization for processing threatening and ambiguous stimuli. Happy faces elicited age-related gamma decreases in attention cortices, implying less attentional demand for positive faces. These findings offer the largest assessment to date of developmental changes in the neural dynamics supporting facial expression processing and mechanisms relevant to emerging psychopathology.