Biomedical Engineering and Bioengineering Commons^™

The Effects Of Separating Visual And Motor Workspaces On The Generalization Of Visuomotor Adaptation Across Movement Conditions, Yuming Lei

Master's Theses (2009 -)

Separating visual and proprioceptive information in terms of workspace locations during reaching movement has been shown to disturb transfer of visuomotor adaptation across the arms. Here, we investigated whether separating visual and motor workspaces would also disturb generalization of visuomotor adaptation across movement conditions within the same arm. In our behavioral study, subjects were divided into four experimental groups (plus three control groups). The first two groups adapted to a visual rotation under a "dissociation" condition in which the targets for reaching movement were presented in midline while their arm performed reaching movement laterally. Following that, they were tested in …

An Fmri Study On Supra-Spinal Contributions To Upper And Lower Limb Motor Control, Shancheng Bao

Master's Theses (2009 -)

The differences in the neural mechanisms contributing to upper and lower extremity movement have not been fully elucidated, and this might be a factor that leads to the ineffectiveness of rehabilitation techniques for most stroke survivors. It is unclear whether therapies designed for upper extremities should also be used for the lower extremities, and vice versa. In this study, fMRI was used to examine the supraspinal control of UE and LE movement in both neurologically intact individuals and people with post-stroke hemiparesis. We compared the location, volume, and intensity of brain activity associated with upper and lower extremity pedaling and …

Biomechanical Evaluation Of An Optical System For Quantitative Human Motion Analysis, Jeffrey D. Kertis

Master's Theses (2009 -)

An eight-camera Optitrack motion capture system was evaluated by performing static, linear dynamic, and angular dynamic calibrations using marker distances associated with upper and lower extremity gait and wheelchair models. Data were analyzed to determine accuracy and resolution within a defined capture volume using a standard Cartesian reference system. Two additional cameras along with AMASS and Visual3D (C-Motion, Inc., Germantown, MD) biomechanical modeling software were used to determine joint kinematics at the pelvis, hip, knee, and ankle of ten control subjects (mean age 21.5 ± 1.65 years). The same data were processed through Nexus (Vicon Motion Systems, Oxford, England) modeling …

Biomechanical Model Of Pediatric Upper Extremity Dynamics During Wheelchair Mobility, Alyssa J. Paul

Master's Theses (2009 -)

Biomechanical analysis has been used by many to evaluate upper extremity (UE) motion during human movement, including during the use of assistive devices such as crutches and walkers. However, few studies have been conducted to examine the upper extremity kinetics during wheelchair mobility, specifically within the pediatric population. In 2000, 90% of wheelchair users (1.5 million people) in the United States were manual wheelchair users, requiring the use of their upper body to maneuver the wheelchair as well as perform other activities of daily living. Among children under the age of 18, the wheelchair was the most used assistive mobility …

Three-Dimensional Biomechanical Model Of Wrist Dynamics During Tasks Of Daily Living, Patrick Roscher

Master's Theses (2009 -)

An understanding of wrist dynamics during functional movements is required to better diagnose and treat wrist injury and disease. Currently, there is a lack of upper extremity (UE) models that combine both the motions and resulting forces that occur in the wrist during daily activities. The purpose of this study is to create a three-dimensional (3D) model of the upper extremity that describes kinematics and wrist kinetics during functional activities. A model of this type could benefit clinical diagnosis, treatment, and follow-up care of orthopaedic and neurological disorders of the wrist. The created dynamic wrist model was used to test …

Development And Performance Of A Sparsity-Exploiting Algorithm For Few-View Single Photon Emission Computed Tomogrpahy (Spect) Reconstruction, Paul Arthur Wolf

Master's Theses (2009 -)

Single Photon Emission Computed Tomography (SPECT) provides noninvasive images of the distribution of radiotracer molecules. Dynamic Single Photon Emission Computed Tomography provides information about tracer uptake and washout from a series of time-sequence images. Stationary ring-like multi-camera systems are being developed to provide rapid dynamic acquisitions with high temporal sampling. Reducing the number of cameras reduces the cost of such systems but also reduces the number of views acquired, limiting the angular sampling of the system. Novel few-view image reconstruction methods may be beneficial and are being investigated for the application of dynamic SPECT. A sparsity-exploiting algorithm intended for few-view …

Examining Lower Extremity Motor Activity Using Magnetoencephalography, Ruth M. Swedler

Master's Theses (2009 -)

The role of the cortex during locomotion remains unclear, but recent advances in neural imaging technologies have aided in developing ways to measure brain activity during motor tasks. One method is by measuring activations produced by neural oscillations which have been associated with a variety of human behaviors, from sleep and rest to cognitive actions and movement. The physiological and functional methods in which oscillations contribute to cortical control are still largely unknown. In this study, we aim to expand that knowledge by examining human cortical activity in the sensory and motor cortices during pedaling using magnetoencephalography (MEG). We hypothesized …

A Large-Scale Mathematical Model Of The Rat Pulmonary Circulation And The Effect Of Chronic Hypoxia, Loolu Rafeeq

Master's Theses (2009 -)

Mathematical models are useful for developing understanding of the behavior of complex biological systems. Recent work on a “physiome” project is aimed at using computational modeling to analyze integrative biological function by developing a simulation system for hypothesis testing (Borg & Hunter, 2003). To date, extensive work on cardiovascular, endocrine and nervous system models has been undertaken. Our objective here is to contribute to this effort by further developing a comprehensive integrative model of the pulmonary circulation. A computational model of the dog pulmonary circulation was originally developed by Haworth et al. (Haworth S. T., 1996; Haworth, Linehan, Bronikowski, & …

Identification Of Proper And Common Names In The Anterior Temporal Lobe: An Fmri Study, Usha Tadimeti

Master's Theses (2009 -)

Temporal lobe epilepsy is a neurological disease that affects millions of individuals worldwide. They are usually treated through surgical resection of portions of the anterior temporal lobe (ATL). Surgical resection is effective for seizure control, but produces language and verbal memory deficits such as anomic aphasia, which adversely affects an individual's quality of life. The purpose of this study was to develop a functional MRI protocol for mapping the function of ATL in healthy subjects, and to better understand the role of the ATL and other regions of the semantic system. Such a protocol may ultimately be used by surgeons …

Advanced Visualization And Intuitive User Interface Systems For Biomedical Applications, David Quam

Master's Theses (2009 -)

Modern scientific research produces data at rates that far outpace our ability to comprehend and analyze it. Such sources include medical imaging data and computer simulations, where technological advancements and spatiotemporal resolution generate increasing amounts of data from each scan or simulation. A bottleneck has developed whereby medical professionals and researchers are unable to fully use the advanced information available to them. By integrating computer science, computer graphics, artistic ability and medical expertise, scientific visualization of medical data has become a new field of study. The objective of this thesis is to develop two visualization systems that use advanced visualization, …

Reducing The Radiation Dose To Women Receiving Cardiac Ct Scans, Michael Hoppe

Master's Theses (2009 -)

This thesis aims to quantify the reduction in radiation dose deposited in glandular breast tissue achieved by using tilted gantry acquisition during cardiac CT scans. Previous work by Halpern et al. suggested using tilted acquisition parallel to the long axis of the patient’s heart. However, for a larger portion of the population this is not feasible due to the design of current scanners (which are limited to maximum tilt angles of 30 degrees). This study investigated the potential dose reduction and image quality effects at commercially available tilt angles between 0-30 degrees through simulation and experimental studies.

Upon IRB approval, …

Abnormal Neuromuscular Fatigue And Motor Performance Of The Knee Extensors Post Stroke, Henry Kuhnen

Master's Theses (2009 -)

Stroke causes paresis in leg muscles, such as the knee extensors, that significantly impairs motor control and function during tasks such as walking. Reduced endurance and increased kinematic asymmetries during walking over time indicate paretic musculature may fatigue more quickly than non-paretic musculature. The primary purpose of this study was to identify abnormalities in neuromuscular fatigue (reduction in force over time) of the paretic knee extensors and associate them with motor performance.

We investigated the effects of repeated six second isometric submaximal (30% of maximum voluntary contraction) knee extensor fatiguing contractions on task failure and motor performance in ten chronic …

Comparison Of An Ankle-Foot-Orthosis And Neuroprosthesis During Level And Non-Level Walking For Individuals Post-Stroke, Michelle Beverly Gallagher

Master's Theses (2009 -)

This study used gait analysis to compare the efficacy of the two foot drop treatments (ankle-foot-orthosis and neuroprosthesis) and to contrast the stimulation control of the two different neuroprosthesis sensors during level and non-level ambulation of post-stroke individuals.

Eight subjects completed two gait analysis sessions, once while using a study-provided articulated AFO and the other while using a WalkAide. After four weeks of acclimation to the device, each subject performed two minute walking trials on a level, inclined and declined treadmill. Kinematic and heart rate data were collected for all sessions. Plantar pressure and WalkAide tilt, heel loading, and stimulation …

Improving Cardiovascular Stent Design Using Patient-Specific Models And Shape Optimization, Timothy J. Gundert

Master's Theses (2009 -)

Stent geometry influences local hemodynamic alterations (i.e. the forces moving blood through the cardiovascular system) associated with adverse clinical outcomes. Computational fluid dynamics (CFD) is frequently used to quantify stent-induced hemodynamic disturbances, but previous CFD studies have relied on simplified device or vascular representations. Additionally, efforts to minimize stent-induced hemodynamic disturbances using CFD models often only compare a small number of possible stent geometries. This thesis describes methods for modeling commercial stents in patient-specific vessels along with computational techniques for determining optimal stent geometries that address the limitations of previous studies.

An efficient and robust method was developed for virtually …

Adaptive Real-Time Decoding Of Brain Signals For Long-Term Control Of A Neuro-Prosthetic Device, Tushar Ashok Dharampal

Master's Theses (2009 -)

Changes in the statistical properties of neural signals recorded at the brain machine interface (BMI) pose significant challenges for accurate long-term control of prostheses interfaced directly with the brain by continuously altering the relationship between neural responses and desired action. In this thesis, we develop and test an adaptive decoding algorithm that can recover from changes in the statistical properties of neural signals within minutes. The adaptive decoding algorithm uses a Kalman filter as part of a dual-filter design to continuously optimize the relationship between the observed neural responses and the desired action of the prosthesis. Performance of the algorithm …

Role Of Tendon Vibration In Multijoint Reflex Coupling In The Hemiparetic Arm Post Stroke, Bani Gadhoke

Master's Theses (2009 -)

Post stroke hemiparesis causes reflex coupling in multiple muscles of the arm, leading to atypical movements that hamper motor control. In particular, people post-stroke can become unstable while holding the arm at the end of a planar motion. Recently, we have found that tendon vibration of the wrist flexors improves the stability of the arm during a hold task. The objective of the current study was to identify the effects of vibration applied to the wrist flexors on the biceps and triceps stretch reflexes, generated using a tendon tapper. In people post-stroke, tendon tap perturbations of the biceps and triceps …

Examining The Relationships Among Injury Outcomes, Velocity And Grip Strength During Dynamic Platform Perturbation, Braden Cripe

Master's Theses (2009 -)

Studies examining the relationship between inputs and outputs for simulated models of dynamically perturbed horizontal platforms are scarce. Most of these scenarios include a standing operator with upper extremity grip, oftentimes subjected to lateral impulses, which may lead to occupant injury. While the detailed study of these collision scenarios is sparse, the prevalence of their application is great.

This thesis aims to identify how two input parameters, velocity change (ÄV) and grip strength, affect injury assessment reference values (IARVs). This is accomplished by using Mathematical Dynamic Modeling (MADYMO) software to simulate the scenarios defined by those inputs. In the simulation, …

Modeling And Computational Framework For The Specification And Simulation Of Large-Scale Spiking Neural Networks, David James Herzfeld

Master's Theses (2009 -)

Recurrently connected neural networks, in which synaptic connections between neurons can form directed cycles, have been used extensively in the literature to describe various neurophysiological phenomena, such as coordinate transformations during sensorimotor integration. Due to the directed cycles that can exist in recurrent networks, there is no well-known way to a priori specify synaptic weights to elicit neuron spiking responses to stimuli based on available neurophysiology. Using a common mean field assumption, that synaptic inputs are uncorrelated for sufficiently large populations of neurons, we show that the connection topology and a neuron's response characteristics can be decoupled. This assumption allows …

Methods For Detecting High-Frequency Oscillations In Ongoing Brain Signals: Application To The Determination Of Epileptic Seizure Onset Zones, Chiran Dilip Doshi

Master's Theses (2009 -)

Epilepsy is a neurological disorder with varied expression. Patients with focal onset seizures that are resistant to medications can benefit from ablative surgery. However, localization of the seizure onset zone (SOZ) and characterization of propagation to secondary areas can be challenging. The present study aimed at developing the appropriate signal processing methodology to detect bursts of interictal high-frequency oscillations (HFOs), as a possible signature of the SOZ, in patients with drug-resistant partial epilepsy. Additionally, invasive interictal and ictal intracranial electroencephalography (iEEG) data and non-invasive electromagnetic source imaging with magnetoencephalography (MEG) data from three subjects were analyzed. We developed a novel …

Tools For Creating Wide-Field Views Of The Human Retina Using Optical Coherence Tomography, Ashavini M. Pavaskar

Master's Theses (2009 -)

Optical Coherence Tomography (OCT) has allowed in-vivo viewing of details of retinal layers like never before. With the development of spectral domain OCT (SD-OCT) details of nearly 2µm axial resolution and higher imaging speed have been reported. Nevertheless, a single volume scan of the retina is typically restricted to 6mm x 6mm in size. Having a larger field of view of the retina will definitely enhance the clinical utility of the OCT.

A tool was developed for creating wide-field thickness maps of the retina by combining the use of already available tools like i2k Retina (DualAlign, LLC, Clifton Park, NY) …

Development Of An Experimental Model To Quantify Lumbar Spine Kinematics During Military Seat Ejection, Steven George Storvik

Master's Theses (2009 -)

The initial phase of a military ejection sequence exerts substantial axial loads on the spinal column. Eccentric inertial loading on the thoracolumbar spine can lead to injury. Most serious injuries due to ejection are in the form of a vertebral fracture, most commonly occurring at the thoracolumbar junction. The objective of the current study was to understand characteristics of a military seat ejection by employing an experimental model designed to simulate the boost or in-rail phase. The model incorporates realistic boundary conditions and is capable of quantifying metrics associated with injury tolerance such as applied accelerations and resultant loads and …

Asymmetric Transfer Of Task Dependent Perceptual Learning In Visual Motion Processing, Sampada Charudatta Wakde

Master's Theses (2009 -)

The effects of perceptual learning (PL) on the sensory representation are not fully understood, especially for higher–level visual mechanisms more directly relevant to behavior. The objective of this research is to elucidate the mechanisms that mediate task dependent learning by determining where and how task dependent learning occurs in the later stages of visual motion processing.

Eighteen subjects were trained to perform a dual–2TAFC visual discrimination task in which they were required to simultaneously detect changes in the direction of moving dots (task–1) and the proportion of red dots (task–2) shown in two stimulus apertures presented in either the left …

Quantification Of 99mTc-Duramycin Uptake Kinetics In The Area-At-Risk After Myocardial Ischemia And Reperfusion, Joseph Capacete

Master's Theses (2009 -)

Myocardial infarction (MI) is a condition in which blood supply to the heart is insufficient. MI is associated with two forms of cell death: apoptosis and necrosis. ^99mTc-duramycin (^99mTc-D) is a novel radiopharmaceutical that detects cell death by recognizing externalized phosphatidylethanolamine. The objective of this study was to develop a compartmental model for ^99mTc-D uptake kinetics in normal and infarct myocardium, and utilize this model to compare the uptake kinetics of ^99mTc-D in MI with that of another radiopharmaceutical, ^99mTc-C2A-GST.

MI was induced in rats which were then injected (i.v.) with ^99mTc-D. Rats …

Design And Validation Of An Mr Conditional Upper Extremity Evaluation System To Study Brain Activation Patterns After Stroke, Rubing Xu

Master's Theses (2009 -)

Stroke is the third leading cause of death and second most frequent cause of disability in the United States. Stroke rehabilitation methods have been developed to induce the cortical reorganization and motor-relearning that leads to stroke recovery. In this thesis, we designed and developed an MR conditional upper extremity reach and grasp movement evaluation system for the stroke survivors to study their kinematic performances in reach and grasp movement and the relationship between kinematic metrics and the recovery level measured by clinical assessment methods. We also applied the system into the functional MRI experiments to identify the ability to study …

Image-Based Quantification Workflow For Coronary Morphology: A Tool For Use In Next-Generation Bifurcation Stent Design, Sara Marie Nomeland

Master's Theses (2009 -)

Coronary artery disease (CAD) occurs in ~200,000 bifurcation lesions annually. Treatment of CAD near bends and bifurcations is challenging and a preferred strategy for bifurcation lesions has yet to be established. However, a favorable treatment option may be elucidated by a more thorough understanding of vessel morphology as well as local hemodynamic alterations caused by current stenting approaches. Computational modeling of human arteries offers an attractive way to investigate the relationships between geometry, hemodynamics and vascular disease. Recent developments also make it possible to perform analysis on realistic geometries acquired noninvasively.

The objective of this work was twofold. The first …

A Non-Rigid Registration Method For Analyzing Myocardial Wall Motion For Cardiac Ct Images, Elizabeth B. Philps

Master's Theses (2009 -)

Cardiac resynchronization therapy (CRT) has a high percentage of non-responders. Successfully locating the optimal location for CRT lead placement on a priori images can increase efficiency in procedural preparation and execution and could potentially increase the rate of CRT responders.

Registration has been used in the past to assess the motion of medical images. Specifically, one method of non-rigid registration has been utilized to assess the motion of left ventricular MR cardiac images. As CT imaging is often performed as part of resynchronization treatment planning and is a fast and accessible means of imaging, extending this registration method to assessing …

Sensitivity Of Motor Adaptation To The Statistical Properties Of An Environmental Load, Timothy Michael Haswell

Master's Theses (2009 -)

Linear, limited-memory models capture many important features of adaptive motor performance during reaching, stepping and pointing. A recent study in our lab found that a model fitted to data obtained from subjects reaching against elastic loads which varied from trial-to-trial later failed to fit the steady-state response behavior of subjects exposed to deterministic, step changes in load. Does motor adaptation depend on statistical properties of the environment (eg. mean load strength and variability)? Neurologically intact volunteers (n=14) made 6 blocks of 100 planar, ballistic, 10cm, out-and-back reaching movements against spring-like loads having equilibrium positions at the hand's starting point. View …

Bi-Planar Postural Stability Model: Fitting Parameters To Patient Data Automatically, Andrew Michael Sovol

Master's Theses (2009 -)

Studies of children with cerebral palsy (CP) have shown that maintaining control of posture in quiet standing is often difficult. Physical therapy and assistive devices, both with or without surgery, may be employed in an effort to improve postural stability. Assessing the effectiveness of such interventions is important for healthcare providers and their patients. A previously created bi-planar model of posture control has been further developed as a method of assessment. This MATLAB and Simulink model has successfully replicated experimental results for typical adults and children, as well as children with CP across three different test conditions: eyes open, eyes …

Upper Extremity Kinetics During Lofstrand Crutch-Assisted Gait In Children, Neha Bhagchandani

Master's Theses (2009 -)

Complete biomechanical analysis helps evaluate the motion during various gait patterns for the upper and lower extremities. Extensive studies have been performed to evaluate unassisted gait patterns, but very little has been accomplished for studying assisted motion. Children with pathologies such as osteogenesis imperfecta, spinal cord injury, and cerebral palsy use assistive devices such as anterior and posterior walkers, canes, Lofstrand and axillary crutches for ambulation purposes.

Statistics show that there are currently about 566,000 crutch users in the United States. The long-term crutch users in this population can suffer various upper limb pathologies associated with extensive upper extremity (UE) …

Capillary Perfusion Kinematics In Lungs Of Oxygen-Tolerant Rats, Madhavi Ramakrishna

Master's Theses (2009 -)

Motivation:

Prolonged exposure to oxygen at high concentrations (hyperoxia), a common treatment for hypoxemia, is toxic to the lungs. Rats exposed to 85% O₂ for 5-7 days develop tolerance to the otherwise lethal effects of 100% O₂. Elucidating the factors that contribute to this tolerance could further our understanding of the mechanisms of lung O₂ toxicity. Since vascular remodeling involving loss of capillary volume and endothelial surface area has been reported in lungs from rats exposed to 85% O₂ for 7 days, we were interested in evaluating the effect of this hyperoxia model on lung …