Amygdala lesion in temporal lobe epilepsy subjects impairs associative learning of emotional facial expressions.

To investigate the role of unilateral amygdala lesions on processing emotions, 22 drug-resistant temporal lobe epilepsy (TLE) subjects (12 with left-sided and ten with right-sided focus) were tested, after anterior temporal lobectomy or selective amygdalo-hippocampectomy on two associative learning tasks containing emotional and neutral facial expressions, respectively. Volumetric lesion analysis was performed on the basis of 3-D MR images. No effects of lesion side were found in TLE subjects. Taken the extent of amygdala damage into account, an interaction effect could be shown between task (learning of neutral facial expressions versus emotional facial expressions) and group (subjects with little versus considerable amygdala damage), indicating worse performance of subjects with considerable amygdala damage in learning emotional facial expressions. Subjects with considerable amygdala damage were also significantly impaired in learning emotional facial expressions when compared with control subjects.