What does it mean to feel? The study of emotions has emerged as a central topic in the new discipline of affective neuroscience. In their new book, "The Feeling Brain," Elizabeth Johnston and Leah Olson trace how work in this rapidly expanding field speaks to fundamental questions: What is the function of emotions? What is the role of the body in emotions? What are "feelings," and how do they relate to emotions? Why are emotions so difficult to control? Is there an emotional brain?