Risk-preference differentiates orbitofrontal cortex responses to freely chosen reward outcomes

To successfully evaluate potential courses of action and choose the most favorable, we must consider the outcomes that may result. Many choices involve risk, our assessment of which may lead us to success or failure in matters financial, legal or health-related. The orbitofrontal cortex (OFC) has been implicated as critical for evaluating choices based on risk. To measure how outcomes of risky decisions are represented in the OFC, we recorded the electrophysiological activity of single neurons while rats made behavioral responses to obtain rewards under conditions of either certainty or risk. Rats exhibited different risk-preferences when given the opportunity to choose. In risk-preferring rats, OFC responses were enhanced following the delivery of large rewards obtained under risk compared with smaller, certain rewards and reward omission. However, in risk-neutral rats, neurons showed similarly enhanced responses to both large rewards obtained under risk and smaller, certain rewards compared with reward omission. Thus, the responses of OFC neurons reflected the subjective evaluation of outcomes in individuals with different risk-preferences. Such enhanced neural responding to risky rewards may serve to bias individuals towards risk-preference in decision-making.