A system for relational reasoning in human prefrontal cortex

The integration of multiple relations between mental iq,resentations is cri tical for higher level cognition. For both deductive and inductive-reasonin g tasks, patients with prefrontal damage exhibited a selective and catastro phic deficit ii? the integration of relations, whereas patients with anteri or temporal lobe damage, marched for overall IQ but with intact prefrontal cortex, exhibited normal relational integration. In contrast, prefrontal pa tients performed more accurately than temporal patients on tests of both ep isodic memory and semantic knowledge. These double dissociations suggest th at integration of relations is a specific source of cognitive complexity fo r which intact prefrontal cortex is essential. The integration of relations may be the fundamental common factor linking the diverse abilities that de pend on prefrontal function, such as planning, problem solving, and fluid i ntelligence.