Neuroimaging studies of bilingual expressive language representation in the brain: potential applications for magnetoencephalography.

Bilingualism is the ability to use two or more languages with equal or near equal fluency. How the brain, often seamlessly, selects, controls, and switches between languages is an enigma. Neuroimaging studies offer the unique opportunity to probe the mechanisms underlying bilingual brain function. Non-invasive methods, in particular, functional MRI (fMRI) and event-related potentials (ERPs), have allowed examination in healthy control populations. Whole-head magnetoencephalography (MEG), a relatively new addition to the cadre of neuroimaging tools, offers a combination of the high spatial resolution of fMRI with the high temporal resolution of ERPs. Thus far, MEG has been applied to the studies of bilingual receptive language, or bilingual language comprehension. MEG has not yet been applied to the study of bilingual language production as such studies have faced more challenges (see Salmelin, 2007 for a review), and these have only recently been addressed. Here, we review the literature on MEG expressive language studies and point out a direction for the application of MEG to the study of bilingual language production.