Central amygdala cells for learning and expressing aversive emotional memories

Anticipatory defensive responses to an aversive or harmful event depend on memories linking the event with the predictive environmental cues. Extensive evidence indicates that the central amygdala is essential for the acquisition and recall of such memories. The evidence came initially from studies that relied on traditional lesion and pharmacological techniques, and recently from studies in which new methodologies were used to target, record and manipulate neuronal activities with improved precision and specificity. In this review, I will discuss the current understanding of the roles of central amygdala neurons in the learning and expression of defensive behaviors, with a focus on the major neuronal populations identified on the basis of their genetic markers.