Prefrontal cortex and rule abstraction: where and whether? Theoretical comment on Moore et al. (2009)

The primate dorsolateral prefrontal cortex is implicated in diverse aspects of behavioral regulation, cognitive control, and memory. However, direct neuropsychological evidence supporting a requirement of this area in functions other than spatial working memory has been scarce. T. L. Moore, S. P. Schettler, R. J. Killiany, D. L. Rosene, and M. B. Moss have shown, for the first time, that lesions of dorsolateral prefrontal cortex in the rhesus monkey (including areas 9 and 46) substantially impair performance in a test of executive function modeled on the Wisconsin Card Sorting Task. The pattern of impairment is consistent with a role for dorsolateral prefrontal areas in rule abstraction but may relate to a role for this area in rule maintenance as well. Interestingly, monkeys with dorsolateral prefrontal lesions do not appear to perseverate in their use of particular rules in the task, different from the common impairment associated with frontal lobe damage in humans. These findings indicate that dorsolateral prefrontal cortex is necessary for some aspects of rule-guided behavior in the primate brain and help illuminate the involvement of different prefrontal areas in different aspects of executive function and rule-guided behavior.