The legacy of the Wernicke-Lichtheim model.

Wernicke established an integrated model of the relation between higher cognitive functions and neurophysiological structure of the human brain in 1874. The previous Bouillaud/Broca view envisaged a mosiac map of centres for specific functions, each of which had no clear inter-relation with other centres or with input/output pathways, and with no theoretical explanation of how each centre operated in relation to more basic neural elements. Wernicke's model overcame these objections, and, with Lichtheim's systematization in 1885, the "Wernicke-Lichtheim model" became the standard neuropsychological theory. In this model, each normal higher function is explained in terms of an underlying neural pathway that includes the input/output systems, related functions employ portions of the pathways used for other functions, pathological syndromes are explained by reference to where in the pathway damage occurred, and previously unobserved pathological syndromes can be predicted. Development of the model at the hands of Lissauer, Dejerine, Liepmann, Geschwind, Heilman, and Ellis and Young is traced.