Bilingualism and healthy aging: Aging effects and neural maintenance.

Speaking more than one language is associated with neurocognitive benefits in seniors (Alladi et al. 2013). Few studies however have tested this hypothesis directly by comparing bilingual seniors who vary in chronological age. We report a Voxel-Based Morphometry (VBM) study showing cumulative effects of age on grey matter volume (GMV) in brain structures that are involved in cognitive control in bilingual seniors and found no differences in RT or accuracy between bilingual and monolingual seniors on a behavioral test of cognitive control called the Attentional Network Task (ANT), and no differences in GMV for selected ROIs between groups. However, chronological age predicted the size of interference and conflict effects for monolingual speakers only. We also observed a more widespread pattern of bilateral aging-effcts in brain regions that are classically associated with aging in monolingual speakers compared to bilingual speakers. Notably, GMV in the dorsal anterior cingulate cortex (dACC) and the level of daily exposure to a second language (L2) independently predict performance on the ANT in bilingual speakers. We conclude that regular (daily) bilingual experience mitigates the typical effects of aging on cognitive control at the behavioral and the neural level.

Speaking in multiple languages: neural correlates of language proficiency in multilingual word production.

The human brain has the fascinating ability to represent and to process several languages. Although the first and further languages activate partially different brain networks, the linguistic factors underlying these differences in language processing have to be further specified. We investigated the neural correlates of language proficiency in a homogeneous sample of multilingual native Ladin speakers from a mountain valley in South Tyrol, Italy, who speak Italian as second language at a high level, and English at an intermediate level. In a constrained word production task under functional magnetic resonance imaging (fMRI), participants had to name pictures of objects in Ladin, Italian and English in separate blocks. Overall, multilingual word production activated a common set of brain areas dedicated to known subcomponents of picture naming. In comparison to English, the fluently spoken languages Ladin and Italian were associated with enhanced right prefrontal activity. In addition, the MR signal in right prefrontal cortex correlated with naming accuracy as a measure of language proficiency. Our results demonstrate the significance of right prefrontal areas for language proficiency. Based on the role of these areas for cognitive control, our findings suggest that right prefrontal cortex supports language proficiency by effectively supervising word retrieval.