Jaak Panksepp, PhD, Emeritus Professor of the Department of Psychology at Bowling Green State University. Panksepp coined the term 'affective neuroscience', the name for the field that studies the neural mechanisms of emotion. "We finally got a handle on the nature of psychological pain, which is very important for depression and other psychiatric disorders. And then we said well there must be something fundamental about the social principal that is in the arena of joy. What would it be? And the answer was obvious that it must be playfulness.