Magnetoencephalographic mapping of the language-specific cortex

Object. In this paper the authors introduce a novel use of magnetoencephalography (MEG) for noninvasive mapping of language-specific cortex in individual patients and in healthy volunteers. Methods. The authors describe a series of six experiments in which normative MEG data were collected and the reliability, validity, and topographical accuracy of the data were assessed in patients who had also undergone the Wada procedure or language mapping through intraoperative cortical stimulation. Conclusions. Findings include: 1) receptive language—specific areas can be reliably activated by simple language tasks and this activation can be readily recorded in short MEG sessions; 2) MEG-derived maps of each individual are reliable because they remain stable over time and are independent of whether auditory or visual stimuli are used to activate the brain; and 3) these maps are also valid because they concur with results of the Wada procedure in assessing hemispheric dominance for language and with the results of c...