An fNIRS investigation into the development of executive function across the school transition period

Abstract

Between the ages of four- to six-years-old, children show remarkable improvements in executive functioning (EF). This thesis aimed to determine which factors contribute to the neurocognitive development of two types of EF, namely, visual working memory (VWM) and inhibitory control (IC). Home-based longitudinal assessments of behaviour, brain function (using functional near-infrared spectroscopy – fNIRS), and academic success were collected across two consecutive years. Chapters 2 and 4 examined which key factors contribute to individual differences in pre-schoolers’ VWM and IC and their neural correlates. Children were categorised into high-performing (HP) and low-performing (LP) groups based on their performance. Chapter 2 found that LPs compared to HPs, increasingly activated the left frontal and bilateral parietal cortices when their VWM capacity was challenged. Further, activation in the left parietal cortex partially mediated the association between parent-reported stressful life events and VWM performance. Chapter 4 found that LPs increasingly activated the bilateral frontal and parietal cortices when their inhibitory processes were strained. Chapters 3 and 5 examined the longitudinal development of VWM and IC and their neural correlates, and how the developmental trajectories of these functions differ by the schooling experience. Further, the extent to which schooling-related changes in EF could predict academic outcomes over time was investigated. Chapter 3 found that children who attended one year of schooling (P1) improved more in VWM than children who stayed in kindergarten (KG). Additionally, P1 children who began the year with greater VWM skills gained more in vocabulary across the school year. Chapter 5 found that P1 children, compared to KG children, showed a greater change over time in activation related to more efficient response monitoring in the bilateral frontal cortex. Further, the change in the left frontal activation difference showed a positive trend with mathematical ability. The novel research presented in this thesis broadens our understanding of individual differences in EF and underlying brain function. Further, these findings reveal how the schooling environment shapes the neurocognitive development of EF which has important implications for academic success.