Neuroscience and Neurobiology Commons^™

Sex Differences In Mood And Anxiety-Related Outcomes In Response To Adolescent Nicotine Exposure, Tsun Hay Jason Ng

Electronic Thesis and Dissertation Repository

Nicotine dependence is causally linked to increased risk of mood/anxiety disorders in later life. Females are reported to experience a higher prevalence of anxiety/depressive disorders and challenges in smoking cessation therapies, suggesting a potential sex-specific response to nicotine exposure and mood/anxiety disorder risk. However, pre-clinical evidence of sex-specific responses to adolescent nicotine exposure is unclear. Thus, to determine any sex differences in anxiety/depressive-related outcomes, adolescent male and female Sprague Dawley rats received nicotine (0.4 mg/kg; 3x daily) or saline injections for 10 consecutive days, followed by behavioural testing, in-vivo electrophysiology and Western Blot analyses. Our results revealed that adolescent nicotine …

The Combined Effects Of Physical Exercise And Cognitive Training On Gait Speed And Primary Motor Cortex Metabolism In Individuals With Mild Cognitive Impairment: A 1h-Mrs Analysis, Jack Thomas Emsey Elkas

Electronic Thesis and Dissertation Repository

Mild cognitive impairment (MCI) is a transitional stage before dementia. Altered gait in MCI has been associated with progression to dementia. Using magnetic resonance spectroscopy, a relationship between primary motor cortex (M1) neurochemistry and dual task gait speed has been reported in MCI. Interventional research suggests exercise, cognitive training, and vitamin D supplementation may benefit MCI, yet the combined effect of these treatments on gait speed and M1 metabolism is unknown. Participants with MCI (N=75) were assigned to one of five intervention arms and dual task cost on gait speed and M1 metabolism was assessed before and five months after …

Characterizing The Function Of B Cells That Accumulate In The Inflamed Central Nervous System In Anti-Myelin Autoimmunity, Lika Chowdhury

Electronic Thesis and Dissertation Repository

While the role of autoimmune T cells has been extensively studied in anti-myelin

autoimmunity, little is known about the function of B cells in multiple sclerosis (MS), a chronic inflammatory disease of the central nervous system (CNS). B cells form clusters with T cells in the meninges directly adjacent to demyelinating lesions. Previous studies have shown that disease progression is dependent on the depletion of specific populations of B cells, but it is not clear which contributes to pathology or how. The purpose of this thesis is to characterize the population of meningeal B cells to determine how they differ …

Spinal Excitability Changes Following Sensory Electrical Stimulation Of The Forearm, Devin K. Box

Electronic Thesis and Dissertation Repository

Sensory electrical stimulation can be used to suppress tremor in Parkinson’s disease. This study investigated the central mechanism underlying this suppression in healthy participants. Reciprocal inhibition (RI) of the wrist flexors before and after a session of sensory electrical stimulation (SES) applied to the antagonistic extensor muscles was assessed using electromyography. It was hypothesized that a 15-minute session of SES, rated by participants as a 3 on a 0-10 pain scale, would produce an increase in RI. Seven of the 18 participants experienced an increase in RI at 0-5 minutes post stimulation, which returned to baseline at 10-15 minutes. The …

Assessment Of Intrinsic Hand Neuromuscular Physiology, Philemon Tsang

Electronic Thesis and Dissertation Repository

Alterations to the peripheral nervous system and neuromuscular physiology may impact hand function in a typical or clinical population, such as individuals with ulnar neuropathy. The mechanisms that influence these positive and negative changes are still not well understood. The three studies within my thesis aim to validate the reliability of decomposition-based quantitative electromyography (DQEMG) measurements and explore the changes in intrinsic hand neuromuscular physiology in a typical aging population and individuals recovering from a surgical intervention for severe ulnar neuropathy.

The purpose of the first study was to determine the test-retest reliability of near-fibre (NF) jiggle, a measure of …

Ultra-High Field Magnetic Resonance Imaging For Stereotactic Neurosurgery, Jonathan Lau

Electronic Thesis and Dissertation Repository

Stereotactic neurosurgery is a subspecialty within neurosurgery concerned with accurate targeting of brain structures. Deep brain stimulation (DBS) is a specific type of stereotaxy in which electrodes are implanted in deep brain structures. It has proven therapeutic efficacy in Parkinson’s disease and Essential Tremor, but with an expanding number of indications under evaluation including Alzheimer’s disease, depression, epilepsy, and obesity, many more Canadians with chronic health conditions may benefit. Accurate surgical targeting is crucial with millimeter deviations resulting in unwanted side effects including muscle contractions, or worse, vessel injury. Lack of adequate visualization of surgical targets with conventional lower field …

The Use Of Current Steering During Subthalamic Deep Brain Stimulation To Alleviate Upper Limb Symptoms Of Parkinson's Disease, Shabna Iftikar Mohideen

Electronic Thesis and Dissertation Repository

Subthalamic (STN) deep brain stimulation (DBS) is an established treatment to alleviate the appendicular motor symptoms of Parkinson's Disease (PD). Current steering during DBS allows the unequal fractionation of current between two electrodes on the lead, resulting in a non-spherical electrical field. It is hypothesized that the way the electrical field is shaped will affect a patient’s upper limb symptom alleviation. Seven PD patients who underwent bilateral STN-DBS were tested over four weeks post-operation. 16 current fractionation settings were tested each week at an amplitude that increased weekly. Optimal setting was defined as the setting that provided the best …

White Matter Inflammation And Executive Dysfunction: Implications For Alzheimer Disease And Vascular Cognitive Impairment, Alexander Levit

Electronic Thesis and Dissertation Repository

White matter integrity is crucial to healthy executive function, the cognitive domain that enables functional independence. However, in the ageing brain, white matter is highly vulnerable. White matter inflammation increases with age and Alzheimer disease (AD), which disrupts the normal function of white matter. This may contribute to executive dysfunction, but the relationship between white matter inflammation and executive function has not been directly evaluated in ageing nor AD. White matter is also particularly vulnerable to cerebrovascular disease, corresponding with the common presentation of executive dysfunction in vascular cognitive impairment (VCI). Thus, white matter may be an important substrate by …

Role Of The Dorsal Striatum In Learning And Decision Making, Nole M. Hiebert

Electronic Thesis and Dissertation Repository

The striatum, the input region of the basal ganglia, has been shown to mediate many cognitive functions. The striatum itself can be functionally segregated into dorsal (DS) and ventral striatum (VS). For more than 60 years, DS has been reported to mediate stimulus-response learning, though evidence has been accruing pointing to a role in decision making. These literatures have been growing independently and an aim of this thesis was to bridge these two bodies of knowledge. We directly investigated the role of DS in stimulus-response learning versus decision making using functional magnetic resonance imaging (fMRI) in patients with Parkinson’s disease …

Cerebral Lactate Metabolism And Memory: Implications For Alzheimer's Disease, Richard Andrew Harris

Electronic Thesis and Dissertation Repository

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by amyloid plaques that are comprised of aggregated amyloid-beta peptides. These toxic proteins promote mitochondrial dysfunction and neuronal cell death. A shift in metabolism away from oxidative phosphorylation and toward aerobic glycolysis, with the concomitant production of lactate, affords neurons a survival advantage against amyloid-beta toxicity. Recent evidence now suggests that aerobic glycolysis in the brain plays a critical role in supporting synaptic plasticity, learning, and memory. However, the role of aerobic glycolysis and lactate metabolism in AD-mediated cognitive decline is unknown. My objective was to test the hypotheses that aerobic glycolysis …

P35. Investigating The Effect Of Maternal Immune Activation On Sensory Filtering, Social Behaviour And Attention, Faraj Haddad

Western Research Forum

Background

Altered brain development is associated with many neuropsychiatric disorders like Autism Spectrum Disorder (ASD) and schizophrenia. Environmental insults can interfere with neurodevelopment, and a prominent example is maternal infection during pregnancy. Epidemiological studies show that children born to mothers who were infected during pregnancy display a higher risk of developing ASD and schizophrenia, and this effect is mainly due to the maternal immune response. Polyinosinic-polycytidilic acid (Poly I:C) is a double stranded RNA molecule that mimics viral markers and elicits an immune response. When injected in pregnant rodents, this model produces offspring that exhibit core symptoms of ASD and …

P30. Optimizing Current Steering In Deep Brain Stimulation For Treating Parkinsonian Axial Motor Symptoms, Daphne Hui

Western Research Forum

Background: The proposed study will investigate deep brain stimulation (DBS), of the subthalamic nucleus (STN) to improve gait dysfunctions in advanced Parkinson’s Disease (PD). DBS requires implantation of electrodes into the brain that contain contacts where current traverses to stimulate neurons. Imprecise electrode implantations are inherent in surgical implantation; thus, contributing to the elusiveness of DBS on gait.

Methods: The proposed investigation will divide current between two contacts to receive 0, 30, 50, 70, or 100% of current, to find the best combination to improve gait. Gait changes associated with fractional combinations will be visually assessed with clinical scales, and …

Resting State Functional Network Disruptions In A Kainic Acid Model Of Temporal Lobe Epilepsy., Ravnoor Singh Gill, Seyed M Mirsattari, L Stan Leung

Physiology and Pharmacology Publications

We studied the graph topological properties of brain networks derived from resting-state functional magnetic resonance imaging in a kainic acid induced model of temporal lobe epilepsy (TLE) in rats. Functional connectivity was determined by temporal correlation of the resting-state Blood Oxygen Level Dependent (BOLD) signals between two brain regions during 1.5% and 2% isoflurane, and analyzed as networks in epileptic and control rats. Graph theoretical analysis revealed a significant increase in functional connectivity between brain areas in epileptic than control rats, and the connected brain areas could be categorized as a limbic network and a default mode network (DMN). The …

Is Online Motor Control Really Impaired In Parkinson's Disease?, Kate E. Merritt

Electronic Thesis and Dissertation Repository

Patients with Parkinson’s disease (PD) are thought to be selectively impaired in consciously-mediated online automatic motor control, whereas the ability to perform subconscious online adjustments remains intact. This present study evaluates the hypothesis that the previously alleged deficits in online motor control in PD are not due to the consciousness of the correction, but rather are attributable to aspects of the prior experimental designs disproportionately penalizing patients for PD-related bradykinesia. Here, we implemented a modified traditional double-step paradigm to investigate consciously-mediated online motor control in PD, in a manner that would be unconfounded by disease-related bradykinesia. Further, we investigated the …

Deep Brain Stimulation And Its Effects On Parkinson Disease Spatiotemporal Gait Parameters., Greydon Gilmore

Electronic Thesis and Dissertation Repository

Subthalamic (STN) deep brain stimulation (DBS) alleviates common appendicular PD symptoms, such as: tremor, rigidity and bradykinesia. However, the effect STN-DBS has on modulating axial gait features has not been properly quantified objectively. The purpose of the present thesis was to investigate the role STN-DBS plays in modulating specific gait features such as pace, asymmetry, variability, rhythm and postural control. It is hypothesized that axial gait function is regulated predominantly by non-dopaminergic control systems. In the acute immediate post-operative phase a surgical effect, named the microlesion effect (MLE), is thought to produce a transient improvement of appendicular and axial symptoms. …

Quantifying The Effects Of Systematic Stn-Dbs Programming On Rest And Postural Tremor In Idiopathic Parkinson Disease Patients, Kristina Ognjanovic

Electronic Thesis and Dissertation Repository

Parkinson’s disease (PD) is a complex neurodegenerative disorder that encompasses both motor and non-motor symptoms. These symptoms and their severity are typically assessed by scale based measures in a clinical setting. Scale- based assessments of PD patients undergoing bilateral subthalamic nucleus deep brain stimulation surgery (STN-DBS) such as the Unified Parkinson Disease Rating Scale (UPDRS) are commonly used in a clinical setting to assess symptom severity and progression. However, the subjective nature of these and other clinical scales call into question both the sensitivity and accuracy of patient assessment over time. An objective quantification of rest and postural tremor of …

Amyloid Beta Resistance And The Warburg Effect: Re-Examining Alzheimer's Disease, Jordan Taylor Newington

Electronic Thesis and Dissertation Repository

Alzheimer’s disease (AD) is characterized by deposition of the amyloid beta (Ab) peptide in the brain, an event which frequently but not universally correlates with nerve cell death. Although most nerve cells die in response to Ab, small populations of cells are able to survive by becoming resistant to Ab toxicity. Understanding the mechanisms by which cells become resistant to Ab may reveal novel treatments for AD. Interestingly, nerve cell lines selected for resistance against Ab exhibit increased glucose uptake and glycolytic flux. Here I show that these metabolic changes are mediated through an upregulation of pyruvate dehydrogenase kinase 1 …

An Investigation Into The Combined Effects Of Β-Amyloid Toxicity And Cerebral Ischemia On The Pathological Expression Of Gangliosides., Jeffrey D. Hepburn

Electronic Thesis and Dissertation Repository

Identifying mechanisms underlying the synergistic pathological interaction between stroke and Alzheimer’s disease (AD) can effectively guide future therapeutic strategies for these highly co-morbid conditions. Aberrant ganglioside expression marked by the pathological accumulation of ganglioside GM3 is common to stroke and AD, yet it is unclear whether GM3 is synergistically enhanced in a comorbid model, or if GM3 is a viable therapeutic target. Adult male Wistar rats received a unilateral ischemic striatal infarct via endothelin-1 (ET-1) injection alone or in combination with bilateral intracerebroventricular injection of the β-Amyloid 25-35 peptide (Aβ) to induce generalized Aβ toxicity (Aβ/ET-1). Animals were sacrificed after …