Studying brain development poses significant methodological challenges when working with vulnerable newborn infant populations. Non-invasive and wearable optical brain imaging technologies may allow for the cot-side study of newborn infants in clinical settings. This has particularly important implications for preterm infants in intensive care, for whom traditional neuroimaging techniques are not readily feasible. Wearable high-density diffuse optical tomography (HD-DOT) has emerged as a promising technology in this pursuit.

In this thesis, I describe the development and application of wearable HD-DOT for newborn infants in clinical settings. Specifically, this technology is applied to study the features of functional brain connectivity (FC) associated with neonatal sleep states, active sleep and quiet sleep, in both term-born and preterm infants. HD-DOT is also electromechanically combined with electroencephalography (EEG) to concurrently study haemodynamic cortical and electrical cortical brain activity in the preterm infant. As a result of the constraints posed by lock-down conditions and a pause on clinical studies during the COVID-19 pandemic, the HD- DOT device is also used to study resting state functional connectivity (RSFC) in the adult brain in the home setting. Findings from this work demonstrate the potential of wearable HD-DOT, and combined EEG-HD-DOT, for the cot-side study of cerebral function during sleep in newborn infants, as well as at-home neuroimaging of resting-state networks in adults.

This work was supervised by: Dr. Topun Austin, Department of Paediatrics, University of Cambridge, and Dr. Robert J. Cooper, Department of Medical Physics and Biomedical Engineering, UCL.