Against the nineteenth century backdrop of the tension between Franz Joseph Gall and Johann Spurzheim's phrenology versus Marie-Jean-Pierre Flourens' equipotentiality, Paul Broca and subsequently Carl Wernicke demonstrated cortical localization of expressive and receptive language functions and their descriptions were soon embraced by the larger medical and scientific community. As additional evidence of hemispheric specialization, John Hughlings Jackson described difficulty with “memory for persons, objects, and places” associated with posterior right hemisphere lesions which led him to introduce the term “imperception” (Finger, 1994). Interest in the frontal lobe was largely restricted to language characteristics associated with lesions of Broca's area as contrasted against those associated with more posterior lesions involving Wernicke's area.
Despite the advances of understanding brain function in the second half of the nineteenth century, the tension between the localizationist versus antilocalizationist camps continued to be present. Current interest in the frontal lobe extends far beyond expressive speech, and involves its role in executive functioning, perseveration, judgment, attention, emotional behavior, and motor programming and regulation, with regional specialization within the frontal system increasingly appreciated for unique contributions to complex human behavior. Thus, localization and antilocalization approaches are able to coexist within a functional system framework. In the present chapter, we will present important cases demonstrating the behavioral impairments associated with prefrontal lobe lesions that have greatly contributed to our understanding of neuropsychological functions of these regions.