The Neural Correlates of Bilingual Language Control : Lifelong Bilingualism and its Mitigating Effects on Cognitive Decline

Speaking a second language requires the ability to keep the two languages apart so that language interference can be avoided, allowing the target language to be used fluently. As such, cognitive control systems are used more extensively in bilinguals compared to monolinguals, a process referred to as bilingual language control (BLC). In the past few decades, the cognitive and structural effects of this lifelong language control experience have been of great interest among researchers within the field of cognitive neuroscience. The present thesis reviews current knowledge on the neural correlates of bilingual language control in high proficient bilingual speakers who actively use both languages in their everyday lives. Language proficiency and frequency of use are important aspects to consider since they both modulate brain activity and structure. Indeed, some studies fail to provide this information. Neuroimaging studies reveal consistent brain activity in a network of cortical and subcortical areas in bilingual speakers during non-verbal and verbal executive control tasks. These brain areas include the anterior cingulate cortex (ACC), prefrontal cortex (PFC), inferior parietal lobes (IPLs), basal ganglia (BG) and the cerebellum. Research also indicates that bilingualism serves as a protective variable against age-related cognitive decline. Studying the effects of lifelong bilingualism on the brain has therefore proven to be important since it can influence an individual’s ability to cope with age decline at a cognitive level.