Three different frameworks for understanding the functions of different regions of prefrontal cortex-working memory, general intelligence, the Supervisory System approach-are compared. Three different lines of neuropsychological evidence are discussed with respect to the third of these frameworks. The contrasting functions of the human left and right dorsolateral prefrontal cortex are then considered. The left is held to be involved in top-down strategic modulation of lower-level systems while the right is considered to be more concerned with the control of checking that on-going behaviour accords with task goals. Finally, the functions of anterior prefrontal cortex are assessed; it is argued that they are concerned with changes in cognitive mode, particularly when that involves the realization of previously set-up intentions.
