FEAR AND THE HUMAN AMYGDALA

We have previously reported that bilateral amygdala damage in humans c ompromises the recognition of fear in facial expressions while leaving intact recognition of face identity (Adolphs et al., 1994). The prese nt study aims at examining questions motivated by this finding. We add ressed the possibility that unilateral amygdala damage might be suffic ient to impair recognition of emotional expressions. We also obtained further data on our subject with bilateral amygdala damage, in order t o elucidate possible mechanisms that could account for the impaired re cognition of expressions of fear. The results show that bilateral, but not unilateral, damage to the human amygdala impairs the processing o f fearful facial expressions. This impairment appears to result from a n insensitivity to the intensity of fear expressed by faces. We also c onfirmed a double dissociation between the recognition of facial expre ssions of fear, and the recognition of identity of a face: these two p rocesses can be impaired independently, lending support to the idea th at they are subserved in part by anatomically separate neural systems. Based on our data, and on what is known about the amygdala's connecti vity, we propose that the amygdala is required to link visual represen tations of facial expressions, on the one hand, with representations t hat constitute the concept of fear, on the other. Preliminary data sug gest the amygdala's role extends to both recognition and recall of fea rful facial expressions.