Altered Medial Frontal Feedback Learning Signals in Anorexia Nervosa. 
In their relentless pursuit of thinness, individuals with anorexia nervosa (AN) engage in maladaptive behaviors (restrictive food choices and overexercising) that may originate in altered decision making and learning.  In this functional magnetic resonance imaging study, we employed computational modeling to elucidate the neural correlates of feedback learning and value-based decision making in 36 female patients with AN and 36 age-matched healthy volunteers (12-24 years).  Participants performed a decision task that required adaptation to changing reward contingencies.  Data were analyzed within a hierarchical Gaussian filter model that captures interindividual variability in learning under uncertainty.  Behaviorally, patients displayed an increased learning rate specifically after punishments.  At the neural level, hemodynamic correlates for the learning rate, expected value, and prediction error did not differ between the groups.  However, activity in the posterior medial frontal cortex was elevated in AN following punishment.  Our findings suggest that the neural underpinning of feedback learning is selectively altered for punishment in AN.