Group-level cortical functional connectivity patterns using fNIRS: assessing the effect of bilingualism in young infants
Date
2021Author
Blanco, Borja
Molnar, Monika
Carreiras, Manuel
Collins-Jones, Liam H.
Vidal, Ernesto
Cooper, Robert J.
Caballero-Gaudes, César
Metadata
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Blanco B, Molnar M, Carreiras M, Collins-Jones LH, Vidal E, Cooper RJ, Caballero-Gaudes C. Group-level cortical functional connectivity patterns using fNIRS: assessing the effect of bilingualism in young infants. Neurophotonics. 2021 Apr;8(2):025011. doi: 10.1117/1.NPh.8.2.025011. Epub 2021 Jun 12. PMID: 34136588; PMCID: PMC8200331.
Abstract
Significance: Early monolingual versus bilingual experience induces adaptations in the development
of linguistic and cognitive processes, and it modulates functional activation patterns during
the first months of life. Resting-state functional connectivity (RSFC) is a convenient approach to
study the functional organization of the infant brain. RSFC can be measured in infants during
natural sleep, and it allows to simultaneously investigate various functional systems. Adaptations
have been observed in RSFC due to a lifelong bilingual experience. Investigating whether bilingualism-
induced adaptations in RSFC begin to emerge early in development has important
implications for our understanding of how the infant brain’s organization can be shaped by early
environmental factors.
Aims: We attempt to describe RSFC using functional near-infrared spectroscopy (fNIRS) and to
examine whether it adapts to early monolingual versus bilingual environments. We also present
an fNIRS data preprocessing and analysis pipeline that can be used to reliably characterize RSFC
in development and to reduce false positives and flawed results interpretations.
Methods: We measured spontaneous hemodynamic brain activity in a large cohort (N ¼ 99) of
4-month-old monolingual and bilingual infants using fNIRS. We implemented group-level
approaches based on independent component analysis to examine RSFC, while providing proper
control for physiological confounds and multiple comparisons.
Results: At the group level, we describe the functional organization of the 4-month-old infant
brain in large-scale cortical networks. Unbiased group-level comparisons revealed no differences
in RSFC between monolingual and bilingual infants at this age.
Conclusions: High-quality fNIRS data provide a means to reliably describe RSFC patterns in
the infant brain. The proposed group-level RSFC analyses allow to assess differences in RSFC
across experimental conditions. An effect of early bilingual experience in RSFC was not
observed, suggesting that adaptations might only emerge during explicit linguistic tasks, or at
a later point in development.