Recent data from studies of the prefrontal cortex (PFC) in humans and laboratory animals are reviewed with particular reference to the anatomical substrates of prefrontal neuropsychological function in health and disease. The PFC has been shown to have a unique pattern of supramodal connectivity with intracortical and subcortical circuits that place the PFC in an anatomical position to subserve "executive" cognitive functions and modulate limbic information to relate to basal ganglia circuits in a highly specific manner and to uniquely control the neurochemical elements of attention and reward. PFC connectivity is also consistent with current hypotheses about prefrontal neuropsychology, which emphasize conscious, goal-directed behavior guided by past experience. PFC connectivity explains the frequency with which prefrontal dysfunction is seen in disease states, which, on the basis of neuroimaging and neuropathology data, can be categorized as either intrinsic or dysconnection disorders.