608 - Dynamic functional connectivity during sleep in term and preterm infants

Publication Number: 3589.608

Katharine Lee, University of Cambridge, Vancouver, BC, Canada; Topun Austin, Cambridge University Hospitals NHS Foundation Trust, Cambridge, England, United Kingdom

Background: Preterm birth has been associated with cognitive, social, and sleep difficulties later in life (Gao, 2017; Stangenes, 2017), potentially exacerbated by disrupted sleep. However, the relationship between sleep states, gestational age (GA), and functional brain development remains poorly understood. Protected sleep in the NICU may offer neuroprotective benefits and improve long-term outcomes. High-Density Diffuse Optical Tomography (HD-DOT), a functional near-infrared spectroscopy (fNIRS) technique, has been used to investigate resting-state functional connectivity (FC) during active sleep (AS) and quiet sleep (QS) in term-aged infants. Dynamic FC analysis assesses time-varying patterns in brain activity, and one approach identifies recurring co-activation patterns (CAPs) using clustering algorithms that capture instantaneous brain configurations (Liu, 2018).

Objective: This study examines dynamic FC in term and preterm infants during sleep to better understand the functional relationship between sleep states and early brain connectivity.

Design/Methods: HD-DOT data were acquired from sleeping newborns at the Rosie Hospital, Cambridge UK (term cohort: n = 44, GA = 40+0 weeks (median), 38+1–42+1 weeks (range); preterm cohort: n = 26, GA = 35+0 weeks (median), 29+1–36+6 weeks (range)). Sleep state was labelled as AS or QS using synchronized video or electroencephalography. Frames were sorted by seed activity for three regions of interest (ROI: frontal, central, parietal), and the top 15% of frames were selected for k-means clustering. Clustered frames were averaged to create CAP maps. Dynamic FC was compared across sleep states by calculating CAP consistency, in-participant fraction, dwell time, and transition likelihood for the term and preterm cohorts. Regional lateralization was compared across sleep states using a weighted laterality index (wLI). CAP metrics were also examined in relation to GA and postmenstrual age.

Results: CAP HD-DOT provided new insight into early formation of higher order networks such as the default mode network. Term and preterm analyses revealed laterality dynamic FC differences between AS and QS. Preterm neonates exhibited more medial CAP arrangements with longer dwell times, suggesting altered maturation of dynamic connectivity.

Conclusion(s): This study was the first to apply CAP analysis to neonatal HD-DOT, revealing sleep state differences that vary with maturation. AS appears to play a critical but diminishing role in the preterm period, with dynamic features such as dwell time positively associated with maturation.