This study will use brain imaging technologies to measure several neurotransmitters (serotonin and dopamine) that contribute to our abilities to respond to reward or inhibit our impulses, and which are known to be altered in the brain of people with anorexia nervosa (AN) and bulimia nervosa (BN). Because palatable food stimulates dopamine secretion, we propose to use a challenge with brain imaging that will stimulate dopamine release which we hypothesize will generate anxiety rather than pleasure in AN, and will help explain why AN restrict eating in order to reduce anxiety. This study will help to understand the unique puzzling symptoms in eating disorders and contribute to finding better methods for identifying effective treatments for these often relapsing and sometimes chronic disorders.