Distinct neural correlates for two types of inhibition in bilinguals: Response inhibition versus interference suppression

To examine the effects of bilingualism on cognitive control, we studied monolingual and bilingual young adults performing a flanker task with functional MRI. The trial types of primary interest for this report were incongruent and no-go trials, representing interference suppression and response inhibition, respectively. Response times were similar between groups. Brain data were analyzed using partial least squares (PLS) to identify brain regions where activity covaried across conditions. Monolinguals and bilinguals activated different sets of brain regions for congruent and incongruent trials, but showed activation in the same regions for no-go trials. During the incongruent trials, monolinguals activated the left temporal pole and left superior parietal regions. In contrast, an extensive network including bilateral frontal, temporal and subcortical regions was active in bilinguals during the incongruent trials and in both groups for the no-go trials. Correlations between brain activity and reaction time difference relative to neutral trials revealed that monolinguals and bilinguals showed increased activation in different brain regions to achieve less interference from incongruent flankers. Results indicate that bilingualism selectively affects neural correlates for suppressing interference, but not response inhibition. Moreover, the neural correlates associated with more efficient suppression of interference were different in bilinguals than in monolinguals, suggesting a bilingual-specific network for cognitive control.