Normal recognition of emotional similarity between facial expressions following bilateral amygdala damage

Bilateral damage to the amygdala in humans has been previously linked to two deficits in recognizing emotion in facial expressions: recognition of individual basic emotions, especially fear, and recognition of similarity among emotional expressions. Although several studies have examined recognition of individual emotions following amygdala damage, only one subject has been examined on recognition of similarity. To assess the extent to which deficits in recognizing similarity among facial expressions might be a general consequence of amygdala damage, we examined this ability in two subjects with complete bilateral amygdala damage. Both subjects had previously demonstrated entirely normal recognition of individual facial emotions. Here we report that these two patients also are intact in their ability to recognize similarity between emotional expressions. These results indicate that, like the recognition of individual basic emotions in facial expressions, the recognition of similarity among emotional expressions does not have an absolute dependence on the amygdala.