Chapter 13. Bilingualism and functional connectivity

Abstract

Four patterns describe how bilingualism affects the functional connectivity of the brain. First, a general observation across most of the studies I surveyed was that bilinguals tended to have higher functional connectivity when compared to monolinguals. Second, increased connectivity with the salience network, a set of regions including the anterior cingulate cortex, the bilateral insula, and subcortical regions is often associated with language training or language diversity where proactive attention to content is paramount. Third, to the degree that individuals have greater exposure or mastery of a second language, (greater proficiency and an earlier or simultaneous age of acquisition) and can rely more on reactive control, studies often show greater bilateral connectivity between the inferior frontal gyri. This is also sometimes associated with decreased activation of frontal regions implying distributed load and greater neural efficiency. The distributed neural pattern in young adulthood may also explain how bilingual older adults are able to sustain their cognition at levels of neuropathology most monolinguals cannot endure. Fourth, in studies that examined anticorrelations between task and rest networks, bilinguals tended to have more distinct (e.g., modular organization), and more strongly anticorrelated task-positive and default-mode networks, and this was often correlated with cognitive control.