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Xie, W., & Richards. J.E. (2018). Development of Brain Functional Connectivity and Its Relation to Infant Sustained Attention in the First Year of Life. International Conference on Infant Studies, Philadelphia, July, 2018.

Introduction: Infant sustained attention is a type of endogenous attention that is characterized by a deceleration in heart rate (HR) and represents the arousal state of infants (Colombo, 2001; Richards, 1989). The study of brain functional connectivity is crucial to understanding the neural mechanisms underlying the improved behavioral performance (Mallin & Richards, 2012) and amplified ERP responses (Xie & Richards, 2016a, b) observed during infant sustained attention. Previous investigations on the development of functional brain connectivity during infancy are primarily confined to the use of functional and structural MRI techniques. The current study examined the relation between infant sustained attention and brain functional connectivity and their development during infancy with high-density EEG recordings. Method: Fifty-nine infants were tested at six (N = 15), eight (N =14), ten (N = 17), and twelve (N = 13) months. Infant sustained attention was defined by measuring infant heart rate changes during infants’ looking. Functional connectivity was estimated with the weighted phase lag index (WPLI) between electrodes on the scalp and between reconstructed cortical source activities in brain regions for infant theta (2 – 6 Hz), alpha (6 – 9 Hz), and beta (9 – 13 Hz) frequency bands. Age-appropriate average MRI templates (Richards et al., 2015) were used to create head and brain models for cortical source reconstruction. Graph theory measures (e.g., path length and clustering coefficient) were used to capture the changes in the overall architecture of brain networks. Figure 1 demonstrates the pipeline for source-space functional connectivity analysis. Results: It was found that infant sustained attention was accompanied by attenuated functional connectivity in the dorsal attention and default mode networks in the alpha band. Figure 2 depicts the connectivity within these two networks and how it was different between sustained attention and inattention. Graph theory analyses showed that there was an increase in path length and a decrease in clustering coefficient during infant sustained attention compared to inattention. The functional connectivity within brain networks and the graph theory measures of path length and clustering coefficient were found to increase with age. The characteristic of small-worldness was found for infants at 6 and 8 months in the alpha and beta bands. Discussion: These findings suggest that infant sustained attention is accompanied by distinct patterns of brain functional connectivity. The attenuated within network connectivity in the alpha band for the dorsal attention and default mode networks might suggest the release of inhibition for these attention networks, which in turn influences infants’ behavioral and physiological activities. The current findings also provide convergent evidence for the rapid development of functional connectivity in brain networks during infancy. The methods used in the current study suggest that cortical source analysis with EEG data can be used with infant participants to study the functional connectivity in brain networks.