Neurolinguistic aspects of bilingualism

Abstract

To study the brain regions and networks that underlie knowledge of more than one language, neurolinguists have traditionally compared what is impaired with what is spared in the language disturbance of aphasia. The sizable literature on polyglot aphasia suggests left-hemisphere dominance for all the languages of most polyglots. Supporting evidence comes from the literature studying lateral dominance in non-brain-damaged bilingual participants and studies of crossed aphasia. Imaging techniques such as cortical stimulation, Positron Emission Tomography(PET), and functional Magnetic Resonance Imaging (fMRI) offer the possibility of interspersed networks for multiple languages in the left hemisphere that are largely but not entirely overlapping. The Evoked Response Potential(ERP) literature, moreover, concurs with the finding of overlap in processing for proficient bilinguals and greater differences for less proficient bilinguals. Directions for future research such as documenting the underpinnings of recent behavioral findings on polyglots' lexicons, individual variability, and language attrition are outlined.