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.

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

The diglossic socio-linguistic situation in Arabic refers to the use of two language varieties in everyday life. Spoken Arabic (SA) is acquired first and used for everyday informal communication, while Literary Arabic (LA) is acquired at school and used for reading, writing and formal functions. Accordingly, the question whether LA functions as a second language had repeatedly been raised. In this study participants performed picture naming in SA in: (i) a simple naming context (SNc); (ii) a first language selection diglossic context mixing SA and LA (fLSc) and (iii) a second language selection bilingual context mixing SA and Hebrew (sLSc). Behavioral and event-related functional magnetic resonance imaging (fMRI) responses were analyzed to examine whether the comparison of picture naming in SA in different contexts will reveal differences related to control processes. Behavioral measures indicated that SA naming in SNc was easier than in fLSc and sLSc, while analysis of fMRI data revealed a significant effect of context. Region of interest analysis in six areas that were activated during the task exhibited two distinct patterns of differences in activation between fLSc and sLSc on the one hand, and SNc on the other. These results are explained in terms of the differential engagement of cognitive control modules and discussed in the light of current views suggesting that domain-general executive modules are adaptively recruited depending on the demands of the interactional context.

Lexical Competition between Spoken and Literary Arabic: A New Look into the Neural Basis of Diglossia Using fMRI.

Diglossia in the Arabic language refers to the socio-linguistic situation in which Spoken Arabic (SA), which is the first to be acquired, is used for everyday communications, while Literary Arabic (LA), acquired at school for reading and writing, is also used for formal functions. Although some authors consider SA and LA as a first and second language, the question of how these are managed in the brain has not yet been understood. Using functional magnetic resonance brain imaging (fMRI) analysis, this study aimed at exploring the neural basis of diglossia during picture naming in two contexts. In the first, healthy young participants were instructed to name each image either in SA or LA on the basis of cue word appearing after the stimulus. In the second, they were instructed to name images either in SA or in Hebrew. Behavioral analysis showed that naming in SA was slightly easier than LA and considerably easier than Hebrew. fMRI analysis showed no difference between SA and LA. Hebrew compared to SA revealed activation differences explainable in terms of engagement of language control modules and second- to first-language effects. These findings, discussed in the light of previous findings in bilingual literature, support the view that dominance in diglossia is modality-dependent.