While the precise locus of such an effect is a matter of current debate [30], under this perspective, it seems plausible that specific types of outcome are not represented in OFC to control LEE011 cost choices directly, but instead to facilitate rapid updating of stimulus-based associations

by allowing animals to accurately assign credit to a particular stimulus or choice that produced them. This in turn will enable accurate stimulus-based value estimates to be passed on to structures involved in choosing what option to select. If correct, the next pressing question is to determine what exact computations OFC performs and how the OFC resolves which elements of the world are relevant for learning. Some potential clues PF-01367338 ic50 can be found in the study by Walton and colleagues discussed above [28]. One consequence of the loss in appropriate credit assignment observed in the OFC-lesioned animals was that it unmasked a separate, intact learning mechanism that could approximate stimulus-outcome associations by using recent choice and reward histories. It is important to note that this faculty was not a novel learning strategy acquired after the lesion; logistic regression analyses showed that these

recency-weighted choice and reward histories affected choices to an almost equal extent pre-operatively and post-operatively in the control and lesion groups. However, in the non-lesioned animals, their Enzalutamide purchase impact on behaviour was dwarfed by the much stronger influence of specific stimulus-outcome pairings. This implies that the way the OFC promotes appropriate credit assignment might therefore be to enhance current task-relevant associations rather than to suppress irrelevant ones. A number of studies have provided evidence for a role of OFC in such a faculty. For instance,

excitotoxic OFC lesions in rats cause them to have abnormally persistent latent inhibition [31]. The lesion rendered them slower to respond to a stimulus relative to unlesioned control animals when it switched from being neutral to becoming reinforced; in other words, the OFC group were impaired at upregulating attention to a familiar but previously behaviourally irrelevant stimulus once it became a useful predictor of future events. By contrast, there is little evidence that OFC lesions that spare medial OFC directly disrupt extinction learning, implying no role for this region in disengaging with a stimulus when it no longer predicts reward 15• and 32]. There is also evidence that OFC might play a role in identifying the type of decision environment the agent currently faces, a sort of ‘relevance filter’ over the vast stimulus (decision) space available to an agent at any given time [6••].