The perspective on language localization provided by stimulation mapping differs from that derived from the effect of lesions. With the stimulation technique, language localization can be mapped in an individual subject, limited only by the surgical exposure; lesions generally damage only one cortical region in a patient, thus providing information on function of only a single area in that individual. The brief duration of stimulation makes any functional reorganization during the time it is applied unlikely; some degree of functional recovery usually occurs after lesions. Both stimulation mapping and lesions provide a different perspective on language localization from that derived from neuronal activity recording or blood flow or metabolic measurement techniques (such as positron emission tomography). The latter techniques indicate where neurons participate in language but not whether those neurons are essential for it. Stimulation and lesions indicate only areas essential for language, for the link with behavior is made only when the behavior fails.
In the present report, the cortical localization of language function as determined by stimulation mapping during naming was investigated in the left, dominant hemisphere of 117 patients. This is the largest experience with dominant hemisphere language localization with this technique reported to date. Several issues were investigated. Does the language area in an individual patient actually occupy all of the language cortex of the classical model? What is the variability in this localization between patients? Are there any demographic characteristics that correlate with the variability?
Dr. Carl Dodrill provided intracarotid amobarbital and VIQ data. Drs. H. Whitaker, C. Mateer, I. Fried, T. Sandquist, and D. Cawthon assisted in patient testing. The operations on 18 patients seen early in the study were performed by Dr. A. A. Ward, Jr., or Dr. A. Wyler.
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This work was supported by National Institutes of Health Grants NS17111, 21724, and 20482.