In Search of Memory: The Emergence of a New Science of Mind

by Eric R. Kandel

triggers of long-term emotional memories in people. Such learned fear is a key component of post-traumatic stress disorder, as well as social phobias, agoraphobia (fear of open spaces), and stage fright. In stage fright and other forms of anticipatory anxiety, a future event (being on stage, for example) is associated with the prospect of something going wrong (forgetting one’s lines). Post-traumatic stress disorder occurs following an extremely stressful event, such as life-threatening combat, physical torture, rape, abuse, or natural disasters. It is manifested as recurrent episodes of fear, often triggered by reminders of the initial trauma. One of the striking features of this disorder, and of learned fear in general, is that the memory of the traumatic experience remains powerful for decades and is readily reactivated by a variety of stressful circumstances. Indeed, after a single exposure to a threat, the amygdala can retain the memory of that threat throughout an organism’s entire life. How does this come about?