Risk-Responsive Orbitofrontal Neurons Track Acquired Salience

• Published in: Neuron (Cambridge, Mass.) Vol. 77; no. 2; pp. 251 - 258
• Main Authors: Ogawa, Masaaki, van der Meer, Matthijs A.A., Esber, Guillem R., Cerri, Domenic H., Stalnaker, Thomas A., Schoenbaum, Geoffrey
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 23.01.2013; Elsevier Limited
• Subjects: Animals; Behavior; Cues; Decision Making - physiology; Frontal Lobe - cytology; Frontal Lobe - physiology; Male; Neurons; Neurons - physiology; Rats; Rats, Long-Evans; Reward; Risk Factors; Rodents
• ISSN: 0896-6273; 1097-4199
• DOI: 10.1016/j.neuron.2012.11.006

Decision making is impacted by uncertainty and risk (i.e., variance). Activity in the orbitofrontal cortex, an area implicated in decision making, covaries with these quantities. However, this activity could reflect the heightened salience of situations in which multiple outcomes—reward and reward omission—are expected. To resolve these accounts, rats were trained to respond to cues predicting 100%, 67%, 33%, or 0% reward. Consistent with prior reports, some orbitofrontal neurons fired differently in anticipation of uncertain (33% and 67%) versus certain (100% and 0%) reward. However, over 90% of these neurons also fired differently prior to 100% versus 0% reward (or baseline) or prior to 33% versus 67% reward. These responses are inconsistent with risk but fit well with the representation of acquired salience linked to the sum of cue-outcome and cue-no-outcome associative strengths. These results expand our understanding of how the orbitofrontal cortex might regulate learning and behavior. [Display omitted] ► Orbitofrontal neurons are reported to signal risk or uncertainty ► Here we show that this activity violates predictions for risk encoding ► Instead orbitofrontal activity is better explained by salience ► This has implications for neuroeconomic models and orbitofrontal function Risk is salient, yet salience can be safe. Here Ogawa et al. took advantage of this asymmetry to dissociate neural correlates of risk and salience. The results indicate that the activity of risk-responsive neurons in the orbitofrontal cortex tracks salience.