Facial expression processing after amygdalotomy.

Facial expression processing impairments were studied in D.R., a 51-year-old woman with a partial bilateral amygdalotomy. D.R. was poor at recognising emotional facial expressions, both in static and moving stimuli. In identity matching tasks (same vs different person) and expression matching tasks (same vs different expression), D.R. was impaired at expression matching with simultaneously or successively presented faces; she experienced difficulties whenever the faces' identities were discrepant with their expressions. For identity matching, she also had problems when simultaneously presented images showed the same face with two different expressions; her deficit in interpreting facial expressions could lead her to mistake differences in expression for a difference in identity. In imagery tasks, D.R. was able to answer questions about the appearance of familiar people, yet she was very poor at imaging facial expressions of emotion. We suggest that her problems in processing facial expressions included impaired knowledge of the patterning of facial features in each emotion; without this, remembering or reconstructing what emotional facial expressions look like is as impaired as perceptual recognition. These findings are consistent with the hypothesis of a role for the amygdala in social behaviour.