When we experience something positive—like receiving a dream birthday cake—our senses help us take in the full experience. You might remember the bright colours, the smell of the frosting, the joy in your chest. Your brain, especially the hippocampus, organizes all that information into a coherent story: “On my sixth birthday, I got a unicorn cake with white icing. It tasted like cotton candy. I was so happy.”

But when something traumatic happens—a car accident, a fall, an assault, or even chronic stress—the process is very different.