In the mid-1990s, scientists discovered that people with posttraumatic stress disorder didn’t just behave differently; their brains actually were different. The hippocampus, located deep within the brain near the amygdala, was a little smaller in people with posttraumatic stress disorder. The hippocampus is intimately involved in learning and memory, and it helps us decide whether something is safe or not. In a disaster—and afterward—it can boost our resilience.
