ABSTRACT
Imagine a mouse identifying a small piece of cheese in the middle of a living room. The cheese can be viewed as a positive stimulus, given its nutritious qualities and ability to satisfy hunger, and induce approach behavior with a goal of consumption. However, the cheese may also be viewed as a potentially negative stimulus, as it exposes the mouse to threats in the environment, thus promoting avoidance behavior. In both cases, the behavior is adaptive and important for survival. The decision to approach or avoid may evolve from a calculation about risk and reward informed by the organism’s motivational state at the time (e.g., hunger) and individual differences that influence the subjective value of a particular reinforcer. Indeed, stimuli labeled as rewards can promote learning, encourage approach behavior, and induce positive emotions (Robbins & Everitt, 1996; Schultz, 2007). But deficits in processing reward information, a hallmark of neuropsychiatric disorders, such as schizophrenia (Gold et al., 2012) and depression (Pizzagalli et al., 2009), can lead to maladaptive decision making—highlighting the need to understand the neural mechanisms supporting reward processing.
