Neuroanatomical and Neurophysiological Considerations

Abstract

It is traditional that a review of the anatomy of language disorders commences with a summary of the history of the disputes between the proponents of the two main streams of thought about brain-language relationships. The ebb and flow of popularity of various localizationist and globalist theories is colorful and instructive, but it is well reviewed elsewhere (Hecaen and Albert, 1978). This issue is no longer relevant in the sense considered by previous generations. Clearly brain functions are not equally represented in all regions. Interhemispheric differences exist in 1) the perception and manipulation of higher level sensory information, 2) the Organization of axial, limb and buccofacial movements and 3) the ability to generate speech and language. These interhemispheric differences are based in part on anatomical asymmetries which are evident in fetal life (Wada et al., 1975). There is intrahemispheric specialization in brain function as well, and within the left hemisphere, much of this specialization in function constitutes the anatomy of language. Even many ostensible critics of the localizationist theories resorted to a system of language Classification that carried implicit functional localization which strongly resembled the classical formulations of Wernicke (1874) and Dejerine (1914). For example, Marie (1917), Head (1926), and Goldstein (1948), despite their reputations as antilocalizationists, utilized systems of Classification based on functional anatomy.