Narrator: This is Science Today. All memories are not created equal. We remember what's emotionally important to us better than we do day-to-day events. Neurobiologist Larry Cahill of the University of California, Irvine says one reason why that's so is an almond-shaped structure in the brain called the amygdala. He and his fellow researchers studied a patient with a diseased amygdala.

Cahill: Now if you were see him and sit down and talk to him you would have trouble finding out that anything's wrong with him.

Narrator: What's wrong is the patient's long-term memory for emotional events.

Cahill: We showed him and a bunch of controls a short story. Most people remember the emotional parts of that story better than the non-emotional parts when you give them a surprise memory test a week later. Not this patient. He remembered the relatively non-emotional parts of the story just fine. But what he didn't do was show the enhanced memory associated with emotion that you and I would.

Narrator: Cahill says that's strong evidence that you need your amygdala to get boosted emotional memories. For Science Today, I'm Steve Tokar.