Functional magnetic resonance imaging (fMRI) enables non-invasive investigation of the neural functions with excellent spatial resolution. Although fMRI has primarily been developed in young adult populations, its use is becoming widespread in paediatrics. However, there are many differences, both behavioural and physical, between adults and children requiring adjustments to imaging and analysis methodology to optimise the results in children. This thesis examines fMRI analysis methodology to improve the detection of developmental changes in the brain. The work uses an emotional and familiar face paradigm that elicits strong BOLD fMRI responses in the fusiform, a region that is still developing across childhood. This face paradigm also enables the comparison of the fusiform responses to the primary visual cortex to link to extensive results in the literature. Thirty five 4-8 year old children and fourteen adults (18-30 years old) were scanned. To address the concern of anatomical size differences between the brains of adults and children, the anatomical variability of the fusiform was measured and the validity of stereotaxic transformation into an adult template was confirmed for the children. To investigate the effect of threshold settings between the adults and children, individual subject analyses of the peak activation location, estimated signal percent change and noise values were calculated using the general linear model (GLM). Similar functional peak locations between individuals were quantitatively selected using a novel application of the activation likelihood estimation (ALE). Also, several different preprocessing steps were evaluated for their ability to correct for the increased motion frequently seen in children, in a quantitative framework (NPAIRS) using canonical variates analysis (CVA), a data driven multivariate model as well as the standard univariate GLM. Functional differences between the adults and the children were identified in the fusiform by applying these optimised procedures. The results of this thesis demonstrate that thresholding and preprocessing pipelines must be made in a group-specific fashion. These methods can also be extended to elderly populations, enabling the investigation of the complete ageing spectrum with fMRI.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OTU.1807/19029 |
| Date | 18 February 2010 |
| Creators | Evans, Jennifer Wai |
| Contributors | Taylor, Margot, Strother, Stephen |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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