Dr. Yuval Neria has spent the last decade researching New Yorker’s emotional responses to traumatic events at Columbia University. He's Israeli and fought in the Arab Israeli war of 1973. He was severely burned, many close friends were killed and some were captured - so he says he has a personal interest in understanding the effect of extreme trauma on human beings. In the WNYC special Living 9/11, he tells about his research: looking at the brains of people who can't let go of traumatic memories.