Resting state functional networks in 1-to-3-year-old typically developing children

Abstract

Brain functional networks undergo substantial development and refinement during the first years of life. Yet, the maturational pathways of functional network development remain poorly understood. Using resting-state fMRI data acquired during natural sleep from 24 typically developing toddlers, ages 1.5-3.5 years, we aimed to examine the large-scale resting-state functional networks and their relationship with age and developmental skills. Specifically, two network organization indices reflecting network connectivity and spatial variability were derived. Our results revealed that reduced spatial variability or increased network homogeneity in one of the default mode network components was associated with age, with older children displaying less spatially variable posterior DMN subcomponent, consistent with the notion of increased spatial and functional specialization. Further, greater network homogeneity in higher-order functional networks, including the posterior default mode, salience, and language networks, was associated with more advanced developmental skills measured with a standardized assessment of early learning, regardless of age. These results not only improve our understanding of brain functional network development during toddler years, but also inform the relationship between brain network organization and emerging cognitive and behavioral skills.

Keywords: Brain development; Brain networks; Early childhood; Functional connectivity MRI; Neuroimaging; Typical development.

Fig. 1

Intrinsic functional networks in typically developing 1-to-3-year-old children. Results of the 20-dimensional group ICA; images are z statistics thresholded at z = 3.0 (p < .001) grouped into functional domain categories as depicted. Images are presented in the Montreal Neurological Institute (MNI) space, in neurological convention (with the left side of the brain represented on the right).

Fig. 2

DMN2 iFC spatial variability across age (partial regression plot, controlling for head motion). The values on the X and Y axes reflect residuals of age in days and standard deviations of DMN2 spatial maps, after controlling for head motion (RMSD).

Fig. 3

Associations between iFC spatial variability in higher-order RFNs (default mode, salience, and language networks) and developmental skills. Partial regression plots between standard deviations of default mode network (A) and salience network (B) spatial maps and MSEL Early Learning Composite (ELC) scores. Panel C depicts a partial regression plot of the association between standard deviations of language network spatial maps and MSEL language index (average of MSEL Receptive and Expressive Language T scores). The values on the X and Y axes reflect residuals of MSEL scores and spatial maps standard deviations, after controlling for head motion (RMSD) and age. Greater MSEL scores correspond to more advanced developmental skills.