Personality predicts responsivity of the brain reward system.

Editor's Note: These short reviews of a recent paper in the Journal, written exclusively by graduate students or postdoctoral fellows, are intended to mimic the journal clubs that exist in your own departments or institutions. For more information on the format and purpose of the Journal Club, please see Review of Beaver et al. Food is a primary reward. There is no doubt that animals and humans find pleasure in the consumption of food and will work hard to obtain it under certain conditions. Foods differ in their rewarding value, with high-calorie foods typically being highly rewarding. In modern societies , food is readily available and food-related advertisements are ubiquitous. Thus, we can be easily motivated to consume rewarding foods even regardless of satiety. The over-consumption of appetizing high-caloric foods has contributed to the dramatic increase in obesity within the past 20 years, making obesity a top 10 global health threat, according to the World Health Organization. However, not everyone overeats. Individual differences in trait reward sensitivity are associated with increased food cravings, hyperphagia, and body weight (Davis et al., 2004). Reward sensitivity, a personality construct of Gray's biologically motivated Reinforcement Sensitivity Theory is thought to control approach behavior and has been linked to the meso-corticolimbic dopamine system (Picker-ing and Gray, 1999). Indeed, a network of interconnected brain regions consisting of orbitofrontal cortex, ventral striatum, amygdala, substantia nigra, and ventral tegmental area (Fig. 1) has repeatedly been implicated in mediating approach behaviors related to food reward in animals and humans. A recent study in The Journal of Neuroscience (Beaver et al., 2006) demonstrates a correlation between trait reward sensitivity and neural activity within the reward network. The authors showed that reward sensitivity , as assessed by the Behavioral Inhibition Scale/Behavioral Activation Scale, predicted neural responses to pictures of appetizing foods in the network of the brain regions outlined in Figure 1. Functional magnetic resonance imaging, in conjunction with a blocked experimental design, was used to record blood oxygenation-level dependent (BOLD) responses while participants passively viewed pictures of foods from four different categories. Volunteers were shown va-lenced pictures of food, which in separate studies were consistently rated as either highly appetizing and pleasant (appetizing foods) or highly disgusting and nauseating (disgusting foods). The comparison conditions included pictures of bland foods that were consistently rated as less pleasant and disgusting, as well as pictures of nonfood objects. Contrasting BOLD responses during experimental …