Thesis Format
Integrated Article
Degree
Doctor of Philosophy
Program
Psychology
Supervisor
Duerden, Emma G.
Abstract
The amygdala is a key element of the limbic system which plays a critical role in emotional processing. Atypical development of the amygdala and the projections to other structures within the limbic system may underlie social-emotional difficulties. The amygdala demonstrates exponential growth throughout childhood, although limited research has examined its detailed growth trajectory early in life and therefore a thorough understanding of typical and atypical development and the association with later social-emotional functioning is lacking.
Preterm birth (weeks' gestation) is highly prevalent and is associated with many developmental delays in addition to impairments in social-emotional functioning. These challenges can be evident early on in life which is suggestive of early brain adaptations.
This dissertation consists of three chapters that examine the development of the amygdala and its correlation with later social-emotional outcomes. Chapter two explores this in a large cross-cohort sample of fetuses and infants born both preterm and full-term. Whereas Chapters three and four examine this in preterm populations. Results from Chapter two suggest that there are both sex and laterality differences in the development of the amygdala and that amygdala volumes are predictive of later social and communicative outcomes. Chapter three found both subnuclei volumes and functional connectivity surrounding the amygdala to be predictive of later social-emotional functioning in childhood. Lastly, results from Chapter four were indicative of associations between amygdala volumes in infancy and social-emotional functioning at preschool age, suggesting that these neurological adaptations are present as early as infancy. The results also identified procedural pain as a moderator of this relationship.
The research presented provides evidence of neurological based biomarkers in both populations of typically developing and preterm children that can used in identifying those at risk of social-emotional difficulties. This is particularly important for children born preterm, given their higher likelihood of difficulties in these areas. Identifying these differences as early as infancy, is promising for the effectiveness of early intervention in improving these symptoms. Labelling pain as a moderating factor and identifying sensitive windows in which it is most impactful can guide clinical approaches to pain management and care in infancy.
Summary for Lay Audience
The amygdala is a structure in the brain that is involved in expressing emotions and human behaviour. The amygdala begins to develop in utero and continues to grow throughout childhood. Preterm birth occurs when a baby is born prior to 37 weeks’ gestation. One of the biggest concerns for parents of preterm born children are challenges socially interacting with peers and the ability to control and express emotions. Because these difficulties are present early on in life, it is likely that these difficulties could be explained by differences in brain development, specifically in the amygdala.
This research consists of three studies that examine the development of the amygdala and its correlation with later social and emotional outcomes. The first study explores this in a large sample of children. The following two studies examine the relationship between the amygdala growth and social and emotional outcomes in preterm populations. In examining the growth of the amygdala in study one, the left side of the amygdala showed quicker growth in infancy and males were found to have larger amygdala compared to females. It was also found that the size of the amygdala in infancy could predict later communication and social skills. The second study discovered that both amygdala size and the strength of the connection between the amygdala and surrounding brain structures that are also involved in processing emotions were related to social and emotional outcomes in preterm children at school age. Lastly, it was found these differences in the structure of the amygdala can be seen as early as in infancy in children born preterm. The study also highlighted that there are specific times in infancy when children are most sensitive to the impact of pain.
The research presented provides evidence that brain-based differences, such as those seen in the amygdala of both children born full-term and those born preterm, are predictive of later social and emotional functioning. By identifying these biological differences early on in life, it is hoped that support for these children who are at-risk can be implemented earlier to improve their functioning and in turn, their later mental health.
Recommended Citation
Mueller, Megan E., "Examining the Association Between Preterm Birth and Social-Emotional Functioning: The Role of the Amygdala and the Exploration of Other Contributing Factors" (2024). Electronic Thesis and Dissertation Repository. 10573.
https://ir.lib.uwo.ca/etd/10573
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