Some people are more likely than others to develop addiction or post-traumatic stress disorder (PTSD) in response to challenging life events. It is not known what differences in brain activity might account for these differences in vulnerability to psychiatric illness. Our lab has determined how to use Pavlovian conditioned approach behaviors to predict which individual rats are more or less likely to develop addiction- or PTSD-like behaviors in response to specific challenges. Much of our work is focused on identifying and manipulating the neurobiology responsible for behavioral differences that predict vulnerability to psychopathology. We also have projects aimed at refining our understanding of the psychological processes underlying individual differences in conditioned responses. Most recently, we have started to translate findings from our animal studies into tasks and measures that can be applied to human subjects.