Narrator: : This is Science Today. Where were you the day that -- well, you fill in the blank. When an important event happens, we remember it more vividly than the events in our day-to-day lives. Why? That's the question studied by neurobiologist Larry Cahill of the University of California, Irvine.

Cahill: It makes sense that not all of our memories are stored equally well. Things that are more important to us, more emotionally arousing, should be stored better on average than those that are not.

Narrator: : Cahill and his fellow researchers think they've discovered how that happens inside the brain. One key is adrenaline.

Cahill: Well, we have a lot of evidence from animal studies, and some recent very exciting evidence from human studies, that indicates that in fact your body's adrenaline system, which gets pumping when you get emotional about something, actually feeds back to your brain and helps you to remember those emotional events better than you would non-emotional events.

Narrator: : The other key to emotional memory is an almond-shaped structure in the brain called the amygdala that works together with adrenaline to imprint memories. For Science Today, I'm Steve Tokar.