A Bilingual Advantage? The Functional Organization of Linguistic Competition and Attentional Networks in the Bilingual Developing Brain

Abstract

Early life experiences are thought to alter children’s cognition and brain development, yet the precise nature of these changes remains largely unknown. Research has shown that bilinguals’ languages are simultaneously active, and their parallel activation imposes an increased demand for attentional mechanisms even when the intention is to use one of their languages (cf. Kroll & Bialystok, 2013). Theoretical frameworks (Adaptive Control hypothesis; Green & Abutalebi, 2013) propose that daily demands of dual-language experiences impact the organization of neural networks. To test this hypothesis, this dissertation used functional Near-Infrared Spectroscopy (fNIRS) to image brain regions in young monolingual and bilingual children (53 English monolinguals, 40 Spanish-English bilinguals; ages 7-9) while they performed a verbal attention task assessing phonological interference and a non-verbal attention task assessing attentional networks. The results did not reveal differences in behavioral performance between bilinguals and monolinguals, however, the neuroimaging findings revealed three critical differences between the groups: (i) bilingual children engaged less brain activity in left frontal regions, than monolinguals, when managing linguistic competitors in one language thus suggesting efficient processing; (ii) bilinguals showed overall greater brain activity, than monolinguals, in left fronto-parietal regions for attentional networks (i.e., alerting, orienting, and executive); and (iii) bilinguals’ brain activity in left fronto-parietal regions during the Executive attentional network was associated with better language abilities. Taken together, these findings suggest that attentional mechanisms and language processes both interact in bilinguals’ left fronto-parietal regions to impact the dynamics of brain plasticity during child development. This work informs neuro-cognitive theories on how early life experiences such as bilingualism impact brain development and plasticity.