Any discussion of the executive function of the PFC would be remiss without at least mentioning working memory, one of the major executive cognitive functions of the PFC. Working memory is a form of sustained attention for the processing of prospective action. Thus, working memory involves the maintenance and manipulation of task-relevant information in the service of planning, problem solving, and predicting forthcoming events (Unterrainer and Owen, 2006; D’Esposito, 2007). Working memory is therefore a form of “active” memory involving sustained attention that is focused on an internal representation and can be distinguished from short-term memory. Although short-term memory often functions in the service of working memory (e.g., bringing a short-term memory online for the purpose of planning and predicting forthcoming events), it is classically viewed as temporary memory storage prior to its storage in long-term memory. Closely related to working memory is attentional “set”, which is essentially attention to motor activity and is used to plan a sequence of forthcoming actions. In a sense, working memory is the representation of the near past whereas set is a representation of the near future (Fuster, 2008), and together they are critical for the temporal organization of behavior.
