Models of Normal Functions and Neuropsychological Deficits

The field of cognitive neuropsychology centers around two coupled goals: to use patterns of cognitive deficits in brain-damaged patients to inform theories and models of how cognitive processes are carried out by the brain, and to apply existing models to explain the specific deficits of individual patients in order to design more effective strategies for remediating these deficits. The roots of this effort can be traced back to the pioneering work of Broca, Wernicke, and Lichtheim in the mid to late 19th century. These neurologists attempted to decompose complex cognitive functions, such as language, into the joint operation of multiple functional “centers” with specific patterns of connectivity between them. Damage either to the centers themselves or to the pathways between them were thought to give rise to distinct patterns of cognitive deficits. Indeed, the traditional scheme used today to categorize patterns of language impairment into distinct clinical syndromes—such as Broca’s aphasia, Wernicke’s aphasia, transcortical sensory or motor aphasia, etc.—