Anterior prefrontal cortex mediates rule learning in humans

Despite a need for rule learning in everyday life, the brain regions involv ed in explicit rule induction remain undetermined. Here we use event-relate d functional magnetic resonance imaging to measure learning-dependent neuro nal responses during an explicit categorization task. Subjects made categor y decisions, with feedback, to exemplar letter strings for which the rule g overning category membership was periodically changed. Bilateral fronto-pol ar prefrontal cortices were selectively engaged following rule change. This activation pattern declined with improving task performance reflecting rul e acquisition. The vocabulary of letters comprising the exemplars was also periodically changed, independently of rule changes. This exemplar change m odulated activation in left anterior hippocampus. Our finding that fronto-p olar cortex mediates rule learning supports a functional contribution of th is region to generic reasoning and problem-solving behaviours.