Vol 10 No 1 18 January 1999 139 Cognitive neuroscience neuroreport 0959-4965 # Lippincott Williams & Wilkins Atypical temporal lobe language representation: MEG and intraoperative stimulation mapping correlation Panagiotis G. Simos CA , Joshua I. Breier, William W. Maggio, William B. Gormley, George Zouridakis, L. James Willmore, 1 James W. Wheless, 1,2 Jules E. C. Constantinou 1 and Andrew C. Papanicolaou Departments of Neurosurgery, 1 Neurology, and 2 Pediatrics, University of Texas Medical School, 6431 Fannin Suite 7.148, Houston, TX 77030, USA CA Corresponding Author FUNCTIONAL brain imaging techniques hold many promises as the methods of choice for identifying areas involved in the execution of language functions. The success of any of these techniques in ful®lling this goal depends upon their ability to produce maps of activated areas that overlap with those obtained through stan- dard invasive procedures such as electrocortical stimula- tion. This need is particularly acute in cases where active areas are found outside of traditionally de®ned language areas. In the present report we present two patients who underwent mapping of receptive language areas preoperatively through magnetoencephalography (MEG) and intraoperatively through electrocortical stimulation. Language areas identi®ed by both methods were located in temporoparietal regions as well as in less traditional regions (anterior portion of the superior temporal gyrus and basal temporal cortex). Importantly there was a perfect overlap between the two sets of maps. This clearly demonstrates the validity of MEG- derived maps for identifying cortical areas critically involved in receptive language functions. NeuroReport 10:139±142 # 1999 Lippincott Williams & Wilkins. Key words: Comprehension; Epilepsy surgery; Functional brain mapping; Magnetoencephalography; Receptive lan- guage; Stimulation mapping Introduction Traditionally, areas involved in the understanding of spoken language are thought to involve the posterior portion of the superior temporal gyrus and adjacent temporo-parietal cortex. Following the initial de- monstration of the putative role of these areas by Wernicke [1] there has been a wealth of evidence from clinicopathological correlations to support this notion [2,3]. Demonstrations of transient de®cits in speech comprehension are particularly impressive in patients undergoing electrocortical stimulation in- traoperatively prior to surgical resection of epilepto- genic tissue, tumors, or arteriovenous malform- ations. While the concept of a receptive language center now appears overly simplistic, it is an indisputable fact that transient electrical interference with normal neuronal activity in a relatively small cortical area can have dramatic effects on the ability to understand speech [4,5]. One of the disadvan- tages of lesion and electrocortical stimulation stud- ies in identifying language-speci®c cortex is their limited scope which, in the former case, is deter- mined by the location and extent of the cortical lesion and, in the latter case, by the extent of the craniotomy which typically exposes only part of the surface of one hemisphere. Recent advances for performing real-time imaging of task-induced cere- bral activation have stirred many expectations re- garding the ability to provide, non-invasively, pictures of the extent of cortical involvement in a particular linguistic function. Ultimately, success of any of these techniques in ful®lling this goal will depend on their ability to produce maps of acti- vated areas that overlap with those obtained through standard invasive procedures such as elec- trocortical stimulation. Non-invasive mapping of language-speci®c areas would be particularly help- ful in guiding surgical decisions, if the maps in- cluded areas not typically involved in receptive language functions, in other words they are not within the traditional limits of Wernicke's area [6± 8]. The present report presents two such cases, in which a perfect agreement was found between the cerebral activation maps acquired in the context of word recognition tasks using magnetoencephalogra- phy (MEG) [9-10] and the results of intraoperative electrocortical stimulation. NeuroReport 10, 139±142 (1999)