"Network Mechanisms Underlying Flexibility in Prefrontal Cortex"

The uniquely human ability to rapidly learn novel tasks from
instruction is important in many aspects of everyday life, yet its
basis in the brain remains a mystery. Using functional MRI and
magnetoencephalography, we found a double dissociation between two
regions in prefrontal cortex, demonstrating that they make distinct
contributions to rapid instructed task learning (RITL) and practiced
task preparation. Dorsolateral prefrontal cortex (DLPFC) was active
early during novel task preparation suggesting it loads individual
task rules into working memory, while anterior prefrontal cortex
(aPFC) was active late suggesting it integrates those rules to
coordinate task performance. In contrast, practiced task preparation
involved these regions in the opposite temporal order (loading
integrated instructions, then individual rules). These findings reveal
two distinct mechanisms for task preparation, bestowing unique
flexibility on prefrontal cortex. The first mechanism involves task
set formation from instructions during RITL, while the second involves
task set retrieval from long-term memory to facilitate familiar task
performance. Both of these mechanisms appear to utilize the
hierarchical relationship between lateral prefrontal regions to
facilitate processing of hierarchical task representations.