Multimethod Investigation of Early Experiences, Brain Development, and Cognitive Outcomes in Bangladeshi Children

Abstract

Children’s experiences during the first few years of life can have particularly profound impacts on cognitive development. Although much progress has been made in elucidating the neural mechanisms underlying these associations, most of this work has focused on high-income settings. It is essential to also explore these mechanisms in children growing up in low- and middle-income countries (LMICs), as variation in cultural norms, values, and environments could lead to contextual differences in the biological embedding of experiences. To address this gap, this dissertation uses a multimethod approach across three studies to examine relations among early experiences, brain development, and cognitive outcomes in children growing up in Dhaka, Bangladesh. In the first study, I examined how electroencephalography (EEG) theta power, a general marker of the strength of neural signals, in the first two years of life is related to earlier experiences in infancy and later cognition at five years of age. After establishing these longitudinal links with general cognition, I then explored how experiences are related to more specific sub-domains of cognition. In Study Two, I once again employed EEG, but extracted event-related potentials (ERPs) to examine precise time-locked neural correlates underlying inhibitory control (a key component of executive functions, or higher-level cognitive skills) at five years of age. In Study Three, I turned to functional near-infrared spectroscopy (fNIRS) to study neural processes underlying auditory processing and their relations to language development (another important aspect of cognition) at two and five years of age. Together, these three studies provide insight into how experiences are related to both brain and behavioral markers of cognition in the Bangladeshi context, suggest that the timing of experiences matters, and show the utility of employing multiple neuroimaging methods to examine brain development more comprehensively. These studies also demonstrate the feasibility of conducting neuroimaging studies in LMICs and provide motivation for future research in more diverse settings. The findings from this dissertation, along with future work building from these results, could inform the design of more effective, targeted, and culturally appropriate interventions to support Bangladeshi children’s cognitive development.