Language Control in Diglossic and Bilingual Contexts: An Event-Related fMRI Study Using Picture Naming Tasks

Native language differences in the structural connectome of the human brain

Is the neuroanatomy of the language structural connectome modulated by the life-long experience of speaking a specific language? The current study compared the brain white matter connections of the language and speech production network in a large cohort of 94 native speakers of two very different languages: an Indo-European morphosyntactically complex language (German) and a Semitic root-based language (Arabic). Using high-resolution diffusion-weighted MRI and tractography-based network statistics of the language connectome, we demonstrated that German native speakers exhibited stronger connectivity in an intra-hemispheric frontal to parietal/temporal dorsal language network, known to be associated with complex syntax processing. In comparison, Arabic native speakers showed stronger connectivity in the connections between semantic language regions, including the left temporo-parietal network, and stronger inter-hemispheric connections via the posterior corpus callosum connecting bilateral superior temporal and inferior parietal regions. The current study suggests that the structural language connectome develops and is modulated by environmental factors such as the characteristic processing demands of the native language.

Bilingualism and domain-general cognitive functions from a neural perspective: A systematic review

A large body of research has indicated that bilingualism - through continual practice in language control - may impact cognitive functions, as well as relevant aspects of brain function and structure. The present review aimed to bring together findings on the relationship between bilingualism and domain-general cognitive functions from a neural perspective. The final sample included 210 studies, covering findings regarding neural responses to bilingual language control and/or domain-general cognitive tasks, as well as findings regarding effects of bilingualism on non-task-related brain function and brain structure. The evidence indicates that a) bilingual language control likely entails neural mechanisms responsible for domain-general cognitive functions; b) bilingual experiences impact neural responses to domain-general cognitive functions; and c) bilingual experiences impact non-task-related brain function (both resting-state and metabolic function) as well as aspects of brain structure (both macrostructure and microstructure), each of which may in turn impact mental processes, including domain-general cognitive functions. Such functional and structural neuroplasticity associated with bilingualism may contribute to both cognitive and neural reserves, producing benefits across the lifespan.

New insights into the neural basis of cognitive control: An event-related fMRI study of task selection processes

To investigate cognitive control, researchers have repeatedly employed task switching paradigms. The comparison of switch relative to repeat trials reveals longer response times and higher error rates, a pattern that has been interpreted as switching costs. Functional magnetic resonance imaging (fMRI) studies have shown the involvement of different brain modules in switching conditions, including prefrontal and parietal regions together with other sub-cortical structures. In this study, the aim was to shed light on the brain basis of cognitive control using an approach that proved useful in previous studies investigating language control in bilinguals. We examined adult participants in one simple color naming context and two task selection mixed contexts. In the first mixed selection context, participants named the color or the shape of the stimulus based on a cue word. In the second, they named the color or the size of the stimulus. It was assumed that the comparison of brain responses to the same color naming in mixed selection contexts vs. in non-selection context will reveal the of engagement of cognitive control/task selection processes. Whole brain analysis of color naming in the different contexts showed a significant main effect of context. The comparison of brain responses in several frontal, parietal and sub-cortical regions, of which some are supposedly involved in cognitive control, demonstrated an increased activation during color naming in mixed relative the simple non-mixed context. The different cognitive control modules described in this study fit with recent bilingual language control and domain general cognitive models.