Bilingual Aphasia: Adapted Language Networks and Their Control

This review focuses on the nature of language recovery in bilingual individuals post-stroke and on the effectiveness of treatment. We consider neuropsychological and neuroimaging papers on bilingual aphasic individuals in the period 2003-2007. We examine the extent to which current evidence supports the notion that different languages are represented in distinct processing areas or are distributed in shared areas with common organizing principles. We argue for the second possibility with the extent of recovery affected by prior proficiency and current usage. We also argue that certain patterns of deficit indicate a problem in controlling the language in use rather than a representational deficit per se. Most studies concern chronic aphasic patients and detailed studies of the effects of treatment and any plastic changes in response to such treatment remain sparse. We conclude with suggestions to further our understanding of recovery and treatment. In order to advance further we need to understand the range of pathways in normal bilinguals that support a given language task so that neural patterns associated with task performance poststroke can be properly interpreted. Imaging regional changes in blood flow immediately post-stroke can help identify the regions and pathways associated with the recovery of function. Functional imaging studies of recovery and treatment in the chronic stage are also critical.