The clinical neuropsychological literature includes under the rubric of “executive function” a wide range of cognitive processes such as focused and sustained attention, fluency and flexibility of thought in the generation of solutions to novel problems, and planning and regulating adaptive and goal directed behavior (Luria, 1966; Hecaen and Albert, 1978; Lezak, 1995). As evident by the wide scope of these processes, executive function has been used to capture the highest order of cognitive abilities. Such abilities are sometimes not only difficult to operationally define but difficult to measure, which has led to a large number of clinical and experimental neuropsychologic tests that have been developed as an attempt to tap this range of abilities (Spreen and Strauss, 1991; Lezak, 1995). Evidence from neuropsychologic, electrophysiologic, and functional neuroimaging research supports a critical role of the frontal lobes (specifically the prefrontal cortex) in executive control of goal-directed behavior (Fuster, 1997). The extensive reciprocal frontal lobe connections to virtually all cortical and subcortical structures places the frontal lobes in a unique neuroanatomic position to monitor and manipulate diverse cognitive processes.

Several neurologic disorders can cause predominantly frontal lobe damage, and in patients with these disorders, executive dysfunction is the predominant finding on examination. These disorders include traumatic brain injury, vascular compromise, neoplasms, herpes encephalitis, epilepsy, and neurodegenerative disease. Thus, very different etiologies of frontal lobe damage can produce a common set of behavioral and cognitive findings.