The inversion effect for neutral and emotional facial expressions on amygdala activity

Neuroimaging studies have reported activation of the amygdala in response to faces and emotional facial expressions. The way in which visual facial information is processed in the amygdala remains, however, unknown. The face inversion effect, a deficit in the processing of inverted compared to upright facial stimuli, has provided an important clue with regard to the visual processes that might be involved. Here we investigated amygdala activity during the presentation of upright and inverted facial expressions of neutral and fearful emotions by measuring functional magnetic resonance imaging (fMRI) while healthy subjects passively viewed these stimuli. The right amygdala was found to be more active in response to upright compared to inverted faces displaying both neutral and fearful emotions. These results suggest that the amygdala is involved in configural/holistic visual processing for faces and emotional facial expressions.

Research Highlights
► The amygdala was more active for upright versus inverted neutral facial expressions.
► The amygdala was also more active for upright versus inverted fearful expressions.
► Such effects were more evident in the right, compared to the left, amygdala.