Amygdala and Prefrontal Cortex Macrostructure and White Matter Microstructure Development in Typical and Atypical Children and Adolescents

The amygdala and prefrontal cortex (PFC) work together to modulate emotions, threat responses, and social cognition. Brain development is region-dependent, with deep grey matter structures such as the amygdala plateauing developmentally before the PFC. The developmental mismatch hypothesis proposes that this difference, or mismatch, in maturational timing underlies elevated adolescent sensation-seeking behaviour. Few prior studies have examined maturational timing differences between grey matter regions and the white matter tracts that move information between them. Further research is required to understand maturational timing differences between females and males and their implications for sex differences in sensation-seeking behaviour. Maturational timing differences must also be examined in atypically developing populations, such as those with prenatal alcohol exposure (PAE), as they may explain behavioural challenges, including elevated sensation-seeking. I used T1 and diffusion-weighted magnetic resonance imaging and generalized additive mixed effects models to characterize amygdala and PFC macrostructure (volume) and uncinate fasciculus and amygdala-PFC white matter tract microstructure (fractional anisotropy [FA], mean diffusivity [MD]) development in typically developing children and adolescents as well as those with PAE. Different maturational patterns were observed between amygdala and PFC volume and tract FA/MD in the typically developing cohort. Females underwent fewer amygdala changes and plateaued before males in all other metrics, resulting in a narrower maturity gap between the amygdala and PFC during late childhood and adolescence. This may explain why females engage in less sensation-seeking behaviour than males. In the PAE cohort, youth with PAE underwent fewer amygdala changes, delayed and shorter periods of PFC development, and various white matter tract alterations compared to their unexposed counterparts, resulting in a wider maturity gap between the amygdala and PFC in adolescence. These findings may explain why youth with PAE engage in more sensation-seeking than their unexposed peers. This thesis provides new insights into the maturational timing of brain regions in typically and atypically developing groups. Typical development work provides a baseline for examining maturational timing differences in other populations, while a robust characterization of children and adolescents with PAE can inform future behavioural studies and promote conversation surrounding neurodevelopmental differences.

Name thesis:degree_name

Master of Science (MSc)

Discipline thesis:degree_discipline

Engineering – Biomedical

Grantor

Schulich School of Engineering

Year dc:date.issued

2025

Author dc:creator

• Roeske, Jamie

Advisor dc:contributor.advisor

• Lebel, Catherine

Committee members dc:contributor.committeemember

• Bray, Signe
• Kopala-Sibley, Daniel
• Long, Xiangyu

Statement dc:rights

• Unless otherwise indicated, this material is protected by copyright and has been made available with authorization from the copyright owner. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.

Language dc:language.iso

en

DOI

https://dx.doi.org/10.11575/PRISM/48648

OAI identifier oai:identifier

oai:ucalgary.scholaris.ca:1880/121058