Biomedical Engineering and Bioengineering Commons^™

Slow Potentials Of The Sensorimotor Cortex During Rhythmic Movements Of The Ankle, Ryan J. Mckindles

Dissertations (1934 -)

The objective of this dissertation was to more fully understand the role of the human brain in the production of lower extremity rhythmic movements. Throughout the last century, evidence from animal models has demonstrated that spinal reflexes and networks alone are sufficient to propagate ambulation. However, observations after neural trauma, such as a spinal cord injury, demonstrate that humans require supraspinal drive to facilitate locomotion. To investigate the unique nature of lower extremity rhythmic movements, electroencephalography was used to record neural signals from the sensorimotor cortex during three cyclic ankle movement experiments. First, we characterized the differences in slow movement-related …

Dynamic Balance Control During Treadmill Walking In Chronic Stroke Survivors, Eric Richard Walker

Dissertations (1934 -)

Maintaining dynamic balance is an important component of walking function that is likely impaired in chronic stroke survivors, evidenced by an increased prevalence of falls. Dynamic balance control requires maintaining the center of mass (COM) within the base of support during movement. During walking, dynamic balance control is achieved largely by modifying foot placement to adjust the base of support. However, chronic stroke survivors have difficulty with both precision control of foot placement, as well as reduced control of COM movement. The objective of this dissertation was to characterize dynamic balance control strategies during walking in chronic stroke survivors. Additionally, …

Novel Paradigms For Visual Field Mapping With Functional Magnetic Resonance Imaging, Yan Ma

Dissertations (1934 -)

The overall goal of this study is to evaluate the existing, and develop new visual field mapping paradigms, which consist of visual stimulation scheme, post-processing and displaying tools using fMRI for both research and clinical applications.

We first directly compared phase mapping and random multifocal mapping paradigms with respect to clinically relevant factors. Multifocal mapping was superior in immunity to noise and was able to accurately decompose the response of single voxels to multiple stimulus locations. In contrast, phase mapping activated more extrastriate visual areas and was more efficient per run in achieving a statistically efficient response in a minimum …

Mechanisms Of Sensorimotor Impairment In Multiple Sclerosis, Matthew Cheeming Chua

Dissertations (1934 -)

Sensorimotor impairments in people with multiple sclerosis (MS) might alter coordination and balance strategy during functional movements. People with MS often have symptoms such as weakness and discoordination in the lower limbs, resulting in poor walking and balance function. This decrease in function can result in falls, decreased community activity, unemployment, and reduced quality of life. As MS is a progressive disease resulting in a range of dysfunction, the amount of lower limb impairment can cause changes to walking and balance strategies to maintain functional performance. The overall objective of this dissertation was to quantify the impairment at the hip …

Reducing Radiation Dose To The Female Breast During Conventional And Dedicated Breast Computed Tomography, Franco Rupcich

Dissertations (1934 -)

The purpose of this study was to quantify the effectiveness of techniques intended to reduce dose to the breast during CT coronary angiography (CTCA) scans with respect to task-based image quality, and to evaluate the effectiveness of optimal energy weighting in improving contrast-to-noise ratio (CNR), and thus the potential for reducing breast dose, during energy-resolved dedicated breast CT.

A database quantifying organ dose for several radiosensitive organs irradiated during CTCA, including the breast, was generated using Monte Carlo simulations. This database facilitates estimation of organ-specific dose deposited during CTCA protocols using arbitrary x-ray spectra or tube-current modulation schemes without the …

Vascular Changes In Type 2 Diabetes Mellitus: Application To Restenosis After Stenting, Hongfeng Wang

Dissertations (1934 -)

Stents used to decrease cardiovascular risk in patients with type 2 diabetes mellitus (T2DM) are prone to increased rates of restenosis. The mechanisms are incompletely elucidated, but low wall shear stress (WSS) and altered intracellular signaling likely contribute. We tested the hypothesis that neointimal hyperplasia (NH) after bare-metal stenting is due to vascular remodeling (enhanced formation of advanced glycation end-products (AGEs), increased downstream vascular resistance (DVR), and decreased WSS), and that decreasing AGEs with ALT-711 (Alagebrium) mitigates this response.

Stents were implanted into the abdominal aorta of Zucker lean (ZL), obese (ZO), and diabetic (ZD) rats. After 21 days, the …

Diffusion Tensor Imaging Of The Central Nervous System Following An Injury To The Spinal Cord And Cell Transplant, Michael Jirjis

Dissertations (1934 -)

The purpose of this dissertation research was to characterize the use of magnetic resonance diffusion tensor imaging (DTI) as a diagnostic and prognostic tool in understanding the changes that occur throughout the spinal cord and brain following a spinal cord injury (SCI) and following stem cell transplant. The diffusion of water inside the nervous system is dramatically altered around the lesion site following a traumatic SCI. However, following damage to the spinal cord, little is known about the diffusion characteristics away from an injury and even less is understood about DTI's sensitivity to structural changes that occur following regenerative transplant …

Foot And Ankle Motion Analysis Using Dynamic Radiographic Imaging, Benjamin Donald Mchenry

Dissertations (1934 -)

Lower extremity motion analysis has become a powerful tool used to assess the dynamics of both normal and pathologic gait in a variety of clinical and research settings. Early rigid representations of the foot have recently been replaced with multi-segmental models capable of estimating intra-foot motion. Current models using externally placed markers on the surface of the skin are easily implemented, but suffer from errors associated with soft tissue artifact, marker placement repeatability, and rigid segment assumptions. Models using intra-cortical bone pins circumvent these errors, but their invasive nature has limited their application to research only. Radiographic models reporting gait …