Atypical temporal lobe language representation: MEG and intraoperative stimulation mapping correlation

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 fulfilling this goal depends upon their ability to produce maps of activated areas that overlap with those obtained through standard invasive procedures such as electrocortical stimulation. This need is particularly acute in cases where active areas are found outside of traditionally defined 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 identified 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.