Developmental differences in the neural mechanisms of facial emotion labeling

Abstract

Adolescence is a time of increased risk for the onset of psychological disorders associated with deficits in face emotion labeling. We used functional magnetic resonance imaging (fMRI) to examine age-related differences in brain activation while adolescents and adults labeled the emotion on fearful, happy and angry faces of varying intensities [0% (i.e. neutral), 50%, 75%, 100%]. Adolescents and adults did not differ on accuracy to label emotions. In the superior temporal sulcus, ventrolateral prefrontal cortex and middle temporal gyrus, adults show an inverted-U-shaped response to increasing intensities of fearful faces and a U-shaped response to increasing intensities of happy faces, whereas adolescents show the opposite patterns. In addition, adults, but not adolescents, show greater inferior occipital gyrus activation to negative (angry, fearful) vs positive (happy) emotions. In sum, when subjects classify subtly varying facial emotions, developmental differences manifest in several 'ventral stream' brain regions. Charting the typical developmental course of the brain mechanisms of socioemotional processes, such as facial emotion labeling, is an important focus for developmental psychopathology research.

Keywords: adolescence; brain; development; emotion; face.

Fig. 1.

Facial emotion labeling task schematic. A. Screenshots from a sample trial. Fixation cross timing varies across trials, and each set of timings was unique to each participant. B. Example of stimuli from one actor. Emotion faces morphed with neutral to create varying intensities of emotion.

Fig. 2.

Accuracy of face emotion identification. Across both adults and adolescents (N = 44), accuracy differs by emotion, depending on intensity level (Emotion × Intensity, F_6,252 = 24.02, P < 0.001). Fifty percent intensity faces are less likely to be identified correctly than 75% or 100% intensity faces, and angry and fearful faces at 50% intensity are less likely to be identified correctly than 50% happy faces. Adults and adolescents do not differ in identifying emotions of different intensities (Age Group × Emotion × Intensity, F < 1, not shown). Brackets indicate significant pairwise comparisons (P < 0.05). Error bars indicate standard error.

Fig. 3.

Developmental differences in brain mechanisms of facial emotion labeling (Age Group × Emotion × Intensity-Quadratic). For all figures, brain image threshold set at whole-brain corrected false probability rate of P < 0.05. Axial view for (A) and (B), sagittal for (C). In all figures, values were extracted from the clusters and averaged for the plots. Asterisks indicate significantly different quadratic trends between adults and adolescents (P < 0.05 FDR-corrected for multiple comparisons).

Fig. 4.

Developmental differences in brain mechanisms of facial emotion labeling (Age Group × Emotion). Brain images in sagittal view. See caption for Figure 3 for further information on brain images and plots. FDR-corrected post hoc analyses indicate that in (A), for adults, Fearful > Happy and Angry > Happy; for adolescents, Fearful > Angry. In (B), for adults, Fearful > Happy > Angry; for adolescents, Fearful > Angry and Happy > Angry; within both Fearful and Happy, adults > adolescents.