Cortical Organization of Language and Verbal Memory Based on Intraoperative Investigations

Abstract

The traditional model of the cortical organization of language was developed in the latter half of the nineteenth century by pooling data on the location of brain damage, particularly as a result of strokes, associated with disturbed language. Essential language areas were usually lateralized to the left hemisphere. Within that hemisphere, the model included the posterior third of the inferior frontal gyrus as an area for language expression (Broca’s area) and a larger area in posterior superior and middle temporal gyri and adjacent parietal operculum for language understanding (Wernicke’s area) (Broca 1861; Wernicke 1874). In more recent versions of this model, the Broca and Wernicke language areas are joined by major white matter pathways, where lesions also disturb language (transcortical aphasias). These pathways provide for serial processing of language from decoding in Wernicke’s area to expression in Broca’s (Geschwind 1970). This model has received support from recent imaging-based studies of brain lesions associated with aphasias (Damasio 1988) and from statistical assessments of formal measure of language deficits with cortical lesions (Kertesz-Phipps 1977). However, other recent studies of these same types of patients have raised questions about major features of the traditional model, including evidence that permanent motor language deficits usually require lesions that extend well beyond Broca’s area, into inferior parietal and superior temporal lobe (Mohr 1976), and that language deficits after frontal lesion include not only expressive problems but also a receptive deficit, particularly for syntax (Goodglass 1976).

The author’s research included in this review is supported by NIH grants NS 17111, 21724, and 20482.