Right BA 10 lesions impair performance on real-world planning but are not sensitive to problem novelty or tower tasks

The prefrontal cortex (PFC) is associated with many cognitive functions, including planning. In the neuropsychology literature planning is reduced to "look ahead" ability and most extensively studied with the "tower" tasks. The most influential theoretical explanation is that planning is required in the absence of a routine solution and PFC patients have difficulty coping with novelty. There is an alternate view of planning that emphasizes the distinction between real world tasks and laboratory tower tasks. This account focuses on the structure of problem spaces and why patients with lesions to right PFC have difficulty navigating ill-structured problem spaces. To further explore these issues we administered two real world travel planning tasks to 56 Vietnam War veterans with penetrating brain lesions and 14 matched normal controls. One planning task involved familiar knowledge while the other involved knowledge unfamiliar to our participants. Participants also completed the D-KEFS tower task. A subset of 18 patients-with lesions to right anterior prefrontal cortex (BA 10)-were impaired in the travel planning task compared to normal controls. The task familiarity/novelty dimension affected performance across participant groups (familiar-task scores were higher than unfamiliar-task scores), but it did not differentially affect any group. An examination of cognitive strategies utilized by participants revealed that the impaired patient group had difficulty maintaining a sufficient level of abstraction and engaged the task at a much more concrete level than other participants. Interestingly, patients impaired in the real-world planning tasks were not impaired in the tower tasks. We conclude that patients with lesions to right BA 10 have difficulty in real-world planning tasks that can be attributed to difficulties in engaging problems at the appropriate level of abstraction.