Medicine and Health Sciences Commons^™

The Relationship Of Plantar Sensation With Standing Balance And Gait Post-Stroke, Stephen Parsons

Electronic Thesis and Dissertation Repository

Gait and balance dysfunction after stroke limit independence and quality of life. Numerous contributing factors have been investigated but the role of sensation deficits has received little attention. This thesis investigated the relationship between plantar cutaneous sensation and 1) standing balance, 2) gait, and 3) use of vision to compensate for sensory loss with a secondary analysis of data from individuals with subacute stroke. Associations between standing balance, gait and sensation were investigated with Spearman correlations. Individuals classified as impaired or intact sensation were compared on gait and standing balance measures. This thesis found plantar sensation is related to standing …

Quantitative Mri Correlates Of Hippocampal And Neocortical Pathology In Intractable Temporal Lobe Epilepsy, Maged Goubran

Electronic Thesis and Dissertation Repository

Intractable or drug-resistant epilepsy occurs in over 30% of epilepsy patients, with many of these patients undergoing surgical excision of the affected brain region to achieve seizure control. Advances in MRI have the potential to improve surgical treatment of epilepsy through improved identification and delineation of lesions. However, validation is currently needed to investigate histopathological correlates of these new imaging techniques. The purpose of this work is to investigate histopathological correlates of quantitative relaxometry and DTI from hippocampal and neocortical specimens of intractable TLE patients. To achieve this goal I developed and evaluated a pipeline for histology to in-vivo MRI …

Regulation Of Metabotropic Glutamate Receptor 5 Activity By Ca2+/Calmodulin-Dependent Protein Kinase Iiα, Fitore Raka

Electronic Thesis and Dissertation Repository

The metabotropic glutamate receptor 5 (mGluR5) is a GPCR coupled to the heterotrimeric G protein Ga_q/11 and activates signaling pathways important for excitatory synaptic transmission. Emerging studies reveal that Amyloid b (Ab) acts as an extracellular scaffold for mGluR5. We have identified Ca²⁺/Calmodulin-dependent protein Kinase IIα (CAMKIIα) as an interacting protein of mGluR5. We hypothesize that CaMKIIα plays a role in mGluR5 signaling and Ab produces differential effects on the regulation of mGluR5 by CAMKIIα. We find that overexpression of CAMKIIα significantly impairs mGluR5-mediated ERK1/2 phosphorylation but does not effect inositol phosphate formation or Ca²⁺ release. …

Investigation Of Sox9 Ablation On Neuroplasticity And Recovery After Ischemic Stroke, Bethany Robin Lenore Bass

Electronic Thesis and Dissertation Repository

Neuroplasticity is a key factor in post-stroke functional recovery. A chief inhibitor of post-stroke neuroplasticity is the expression of chondroitin sulfate proteoglycans (CSPGs). Recent research has shown that the transcription factor SOX9 is responsible for upregulating the expression of CSPGs in the injured central nervous system. Accordingly, CSPG levels are significantly lower in mice with the Sox9 gene conditionally knocked out. The purpose of this study was to determine how Sox9 ablation affects neuroplasticity and recovery after stroke. Behavioural test results revealed that Sox9 KO mice exhibited significantly improved functional recovery after stroke compared to controls. This correlated with increased …

The Antisaccade Task: Visual Distractors Elicit A Location-Independent Planning 'Cost', Jesse C. Desimone

Electronic Thesis and Dissertation Repository

Prosaccades are rapid eye movements with direct stimulus and response relations and are designed to bring the fovea onto a target or area of interest. In contrast, antisaccades require the inhibition of a prosaccade and the evocation of a saccade to a target’s mirror-symmetrical location. Previous work has shown that a remote (i.e., midline, contralateral) – but not proximal (i.e., ipsilateral) – task-irrelevant distractor relative to a visual target delays prosaccade reaction times (RT) (i.e., remote distractor effect: RDE). To my knowledge, however, no work has examined whether antisaccade RTs are similarly influenced by a RDE. Accordingly, I sought to …

Task-Switching In Oculomotor Control: Systematic Investigations Of The Unidirectional Prosaccade Switch-Cost, Jeffrey Weiler

Electronic Thesis and Dissertation Repository

An antisaccade requires suppressing a stimulus-driven prosaccade (i.e., response suppression) and remapping a target’s spatial location to its mirror-symmetrical position (i.e., vector inversion). Notably, my previous work demonstrated that the successful execution of an antisaccade selectively lengthens the reaction time (RT) of a subsequently completed prosaccade (i.e., the unidirectional prosaccade switch-cost; Weiler & Heath, 2012a; Weiler & Heath, 2012b). Thus, the objective of this dissertation was further investigate, and ultimately provide a mechanistic explanation for the unidirectional prosaccade switch-cost.

In Chapter Two, I demonstrate that the magnitude of the unidirectional prosaccade switch-cost is not dependent of the number of …

Deep Learning Via Stacked Sparse Autoencoders For Automated Voxel-Wise Brain Parcellation Based On Functional Connectivity, Céline Gravelines

Electronic Thesis and Dissertation Repository

Functional brain parcellation – the delineation of brain regions based on functional connectivity – is an active research area lacking an ideal subject-specific solution independent of anatomical composition, manual feature engineering, or heavily labelled examples. Deep learning is a cutting-edge area of machine learning on the forefront of current artificial intelligence developments. Specifically, autoencoders are artificial neural networks which can be stacked to form hierarchical sparse deep models from which high-level features are compressed, organized, and extracted, without labelled training data, allowing for unsupervised learning. This thesis presents a novel application of stacked sparse autoencoders to the problem of parcellating …