Calculating the cost of acting in frontal cortex.

To make informed and successful decisions, it is vital to be able to evaluate whether the expected benefits of a course of action make it worth tolerating the costs incurred to obtain them. The frontal lobe has been implicated in several aspects of goal-directed action selection, social interaction, and optimal choice behavior. However, its exact contribution has remained elusive. Here, we discuss a series of studies in rats and primates examining the effect of discrete lesions on different aspects of cost-benefit decision making. Rats with excitotoxic lesions of the anterior cingulate cortex became less willing to invest effort for reward but showed no change when having to tolerate delays. Orbitofrontal cortex-lesioned rats, by contrast, became more impulsive, yet were just as prepared as normal animals to expend energy to obtain reward. The sulcal region of primate anterior cingulate cortex was also shown to be essential for dynamically integrating over time the recent history of choices and outcomes. Selecting a particular course of action may also come at the expense of gathering important information about other individuals. Evaluating social information when deciding whether to respond was demonstrated to be a function of the anterior cingulate gyrus. Taken together, this indicates that there may be dissociable pathways in the frontal lobe for managing different types of response cost and for gathering social information.