One-third of the task-sensitive neurons in ACC tracked the monkey’s position in the response schedule and had firing rates that changed monotonically as the monkeys approached the reward. The activity disappeared when information about the animal’s position in Enzalutamide in vitro the sequence of responses, and therefore information about how many more responses had to be made before reward could be expected, was absent. By contrast, only 3% of OFC neurons exhibited activity that
was monotonically dependent on position in the response sequence. OFC neurons were not simply unresponsive to the task but also had activity that reflected other features of the task, for example, whether or not a reward had just been delivered on the last trial or whether or not reward was expected on the current trial. The OFC sensitivity to recent reward delivery was independent of whether or not there was information available to inform the animal
about the schedule of responses selleck chemical to be made. In summary, while OFC activity might facilitate the relative comparison of rewards ACC activity reflects the integration of both future reward and effort expectations. In a task that involves the execution of a plan involving a sequence of actions directed toward a distant reward it is clear that integrated value neurons in the ACC will have particular importance. In addition to value selectivity, these cells either themselves possess response selectivity or are adjacent to and interconnected with neurons that have response selectivity. The fact that OFC neurons represent
different facets of choice values independently, such as effort, Sitaxentan reward probability, and reward payoff size (Kennerley et al., 2009), as well as the taste and texture of rewards (Rolls, 2008), may mean that the OFC is especially important when the context means that only certain features of the reward are relevant for the decision in hand. The OFC’s representation of reward value may also be important when a particular feature of the reward is changing in value, for example, when a reward’s value changes as a result of satiety (Murray and Izquierdo, 2007 and Murray and Wise, 2010). The aim of this review has been to sketch emerging evidence concerning the role of frontal cortical areas in reward-guided learning and decision-making. Dividing frontal cortex into four regions facilitates comparisons between studies conducted with monkeys and humans and makes it possible to review distinct hypotheses about frontal functions. It is not, of course, meant to imply that there are not interactions between the areas; nor is it meant to suggest that they do not operate in tandem in many real-world situations. Equally it is important to acknowledge that further and more fine-grained functional subdivisions are emerging within these four major regions.