The contribution of orbitofrontal cortex to action selection.

A number of recent findings suggest that the orbitofrontal cortex (OFC) influences action selection by providing information about the incentive value of behavioral goals or outcomes. However, much of this evidence has been derived from experiments using Pavlovian conditioning preparations of one form or another, making it difficult to determine whether the OFC is selectively involved in stimulus-outcome learning or whether it plays a more general role in processing reward value. Although many theorists have argued that these are fundamentally similar processes (i.e., that stimulus-reward learning provides the basis for choosing between actions based on anticipated reward value), several behavioral findings indicate that they are, in fact, dissociable. We have recently investigated the role of the OFC in the control of free operant lever pressing using tests that independently target the effect of stimulus-outcome learning and outcome devaluation on performance. We found that OFC lesions disrupted the tendency of Pavlovian cues to facilitate instrumental performance but left intact the suppressive effects of outcome devaluation. Rather than processing goal value, therefore, we hypothesize that the contribution of the OFC to goal-directed action is limited to encoding predictive stimulus-outcome relationships that can bias instrumental response selection.