Mapping of the laueguage specific cortex function with magnetoencephalography

This paper describes a new application of magnetoencephalography (MEG), namely, presurgical evaluation of patients with brain lesions in the vicinity of areas that are known or suspected to subserve linguistic functions. At present, presurgical determination of hemispheric dominance for language is accomplished through the "Wada" procedure and detailed mapping of the areas specialized for language, within the dominant hemisphere, is carried out through direct stimulation of small patches of the exposed cortex while the patient is kept awake and engaged in language tasks. We are now presenting evidence that the results of MEG evaluations of both, hemispheric dominance and of precise localization of language-specific cortical areas concur with the results of the Wada procedure and the results of intraoperative electrical stimulation mapping. This evidence suggests that the MEG procedure may supplement or replace, in the future, the two traditionally used invasive methods of mapping of the language-specific cortex and of determining hemispheric dominance for language.