Functional Brain Development: Longitudinal Studies in Infants using High-Density EEG

Abstract

The thesis examines the functional brain development of visual motion perception in full-term and preterm infants in the first year of life using high-density electroencephalogram (EEG). The relationship between behavioural development and the development of the underlying neuronal processes is explored through EEG measurements of neuronal electrical activity as a function of perception of visual motion information for prospective control. It provides information about the little-known brain changes that support the development of prospective control and about processes, such as preterm birth, that may compromise it. It outlines the development of the visuo-cognitive systems, especially visual motion perception for the control of anticipatory actions primarily using visual motion paradigms of looming, and optic flow. The brain’s response to looming information showed older infants to have improved brain development compared to younger infants, a possible result of specialization and rapid tuning of neural pathways. In investigating how the flow of looming information is organized in the visual areas of the developing infant brain to allow for resonance to occur, it was found that the brain’s organization can be flexible where structurally different neural tissues can be involved in flexible, temporarily assembled structures, with neuronal functions being dependent on the context within which the neuronal ensembles operate. The functional discrimination between different radial motion patterns in infancy is shown to become more prominent towards the end of the first year of life when full-term infants detect forwards optic flow more efficiently than reversed optic flow or random visual motion. Preterm infants showed no such developmental differences. However, both full-term and preterm infants showed desynchronised theta-band oscillatory activities when processing motion, with only the full-term infants at 12 months further showing synchronisations in alpha-beta frequency bands in response to motion. The poorer responses in the preterm infants could be related to impairment of the dorsal visual stream specialized in the processing of visual motion. Full-term infants at 12 months with a substantial amount of self-produced locomotor experience and neural maturation coupled with faster oscillating cell assemblies, rely on the perception of structured optic flow to judge time-space environmental motion dynamics more efficiently.