The Role of Amygdala in Emotional and Social Functions: Implications for Temporal Lobe Epilepsy

Temporal lobe epilepsy is among the most frequent causes of chronic and drug-resistant seizure disorders. It is typically associated with lesions involving critical limbic structures within the anterior medial temporal lobe, such as the amygdala and hippocampus. While the role of the hippocampus and adjacent cortical regions in memory function is now well established, the role of the amygdala and related brain circuits is still poorly known. The amygdala is a complex neural structure implicated in several aspects of emotional and social behaviour, but the varieties and the consequences of amygdala dysfunction in patients with temporal lobe epilepsy remain unclear, and insufficiently examined in standard neuropsychological assessments. Here we review data from recent research in humans indicating that amygdala lesions may impair selective domains of affect and cognition, all related to the appraisal of emotional and social significance of sensory events. We describe neurophysiological and behavioural evidence to illustrate how the amygdala may contribute to a wide range of affective functions, including recognition of facial expressions, perception of gaze direction, modulation of attention and memory, perception of musical emotions, theory of mind, plus mood and psychiatric disorders. We argue that a more systematic assessment of affective functions mediated by the amygdala and related circuits might provide useful information about temporal lobe pathology and neuropsychological outcome after surgery