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Full-Text Articles in Biomedical Engineering and Bioengineering

Optical Perturbation Of Protein Kinase A Activity Via Photoactivatable Inhibitor Peptides, Peter Chen May 2023

Optical Perturbation Of Protein Kinase A Activity Via Photoactivatable Inhibitor Peptides, Peter Chen

McKelvey School of Engineering Theses & Dissertations

Protein Kinase A (PKA) plays important roles in diverse biological processes such as sleep, long term memory, and synaptic plasticity. In addition, PKA also acts as an integrator of neuromodulator signaling though G protein-coupled receptor activation. However, despite genetic knockout and pharmacological inhibition experiments that demonstrate the importance of PKA, it is unclear where, when, or how PKA plays these roles in cellular physiology and behavior. In order to better understand the function of PKA in these processes, and how neuromodulator signaling drives complex behavioral changes, there exists a need for a method to selectively activate/inactivate PKA with high spatial …


Preparing Non-Human Primates To Study Hand-Eye Coordination In Frontal Eye Fields (Fef) During Delayed Movement Task, Juliusz Cydzik May 2023

Preparing Non-Human Primates To Study Hand-Eye Coordination In Frontal Eye Fields (Fef) During Delayed Movement Task, Juliusz Cydzik

McKelvey School of Engineering Theses & Dissertations

ABSTRACT OF THE THESIS Preparing Non-Human Primates to Study Hand-Eye Coordination in Frontal Eye Fields (FEF) During Delayed Movement Task by Juliusz Cydzik Master of Science in Biomedical Engineering Washington University in St. Louis, 2023 Professor Lawrence Snyder, Chair Hand-eye coordination enables humans and non-human primates to use their hands and eyes to perform various tasks. We are interested in coordination at the systems level, where saccades and reaches are encoded. The parietal reach region (PRR), situated at the posterior end of the intraparietal sulcus (IPS) and overlapping portions of the medial intraparietal area (MIP) and V6a, is commonly attributed …


Development Of Noninvasive Biomarkers For Cervical Spondylotic Myelopathy, Dinal Jayasekera Aug 2022

Development Of Noninvasive Biomarkers For Cervical Spondylotic Myelopathy, Dinal Jayasekera

McKelvey School of Engineering Theses & Dissertations

Cervical spondylotic myelopathy (CSM) represents the most common cause of chronic spinal cord injury (SCI) in adults. Many patients with symptomatic CSM will experience a decline in neurological function and consequently undergo surgical decompression. Unfortunately, surgeons are unable to adequately counsel patients about the benefits of surgery because the natural history of disease and outcome after decompression vary widely among patients. This can hinder the decision-making capacity of patients and physicians. Therefore, we require additional tools to help guide therapy and counsel patients with CSM. Noninvasive biomarkers present valuable potential as predictors of a patient’s recovery in the long term. …


Towards The Discovery Of Prognostic Biomarkers For Glioblastoma Using Resting-State Functional Connectivity, Andy G. S. Daniel Aug 2021

Towards The Discovery Of Prognostic Biomarkers For Glioblastoma Using Resting-State Functional Connectivity, Andy G. S. Daniel

McKelvey School of Engineering Theses & Dissertations

Gliomas are highly diffusive, primary brain tumors. The most malignant form, glioblastoma, has a dismal survival rate: 14-17 months following the current standard of care, which consists of surgery, radiation, and chemotherapy. Insights into the molecular, cellular, and microenvironmental components of glioblastoma have revealed a vast array of factors utilized to support its proliferation, infiltration, and resistance to treatment. Recent advancements have also identified diagnostic and prognostic biomarkers that are now being used to guide treatment planning. However, survival has improved only marginally, thus emphasizing the continued need for novel biomarkers and treatment strategies. Given its delicate location in the …


Long-Term Neural Activity Recorders Using Energy-Based Sensing, Compressive Computation And Data Logging, Darshit Mehta Aug 2021

Long-Term Neural Activity Recorders Using Energy-Based Sensing, Compressive Computation And Data Logging, Darshit Mehta

McKelvey School of Engineering Theses & Dissertations

Insects are ideal candidates for developing bio-robotic systems owing to their ability to thrive in almost any environment. For example, neurons in their exquisite olfactory sensory systems can be tapped to create a sensing platform for standoff chemical monitoring. However, for enabling such cyborg systems, it is vital that the neural activity of a freely behaving organism can be measured for long periods of time. The current state-of-the-art neural recording techniques are power-intensive and they either need batteries, which make them too bulky for insects, or they have to maintain a continuous telemetry link to an external power source which …


Cortical Organization In Humans And Nonhuman Primates: The Evolution Of Cognitive Areas And Circuits, Chad Joseph Donahue May 2021

Cortical Organization In Humans And Nonhuman Primates: The Evolution Of Cognitive Areas And Circuits, Chad Joseph Donahue

McKelvey School of Engineering Theses & Dissertations

Similarities in organization of cerebral cortex in humans and nonhuman primates offer the promise of leveraging data from invasive animal studies to better understand the complexities of the human brain, particularly those related to higher cognitive function (e.g. attention, working memory, language). Such comparisons necessitate the identification of convincing cortical homologues (areas or regions presumed to have derived from a common ancestor), requiring an accurate interspecies mapping of cortical areas and features. To this end, I describe (i) a survey of connectivity and its measures across primate species, particularly retrograde tracing and diffusion tractography, (ii) a morphometric analysis of cognitive …


Neural Coding And Organization Principles In The Drosophila Olfactory System, Haoyang Rong Jan 2021

Neural Coding And Organization Principles In The Drosophila Olfactory System, Haoyang Rong

McKelvey School of Engineering Theses & Dissertations

Sensory systems receive and process external stimuli to allow an organism to perceive and react to the environment. How is sensory information subsequently represented, transformed, and interpreted in the neural system? In this dissertation, I have investigated this fundamental question using the fruit fly (Drosophila melanogaster) olfactory system.Chemical cues are transduced into neural signals in the insect antenna by the olfactory receptor neurons (ORNs). The ORNs send their axons to the antennal lobe (AL), with each ORN type innervating a specific neuropil (glomerulus), where they synapse onto excitatory and inhibitory projection neurons (ePNs and iPNs). The ePNs project their axons …


Approaches To Understanding The Function Of Intrinsic Activity And Its Relationship To Task-Evoked Activity In The Human Brain, Dohyun Kim May 2019

Approaches To Understanding The Function Of Intrinsic Activity And Its Relationship To Task-Evoked Activity In The Human Brain, Dohyun Kim

McKelvey School of Engineering Theses & Dissertations

Traditionally neuroscience research has focused on characterizing the topography and patterns of brain activation evoked by specific cognitive or behavioral tasks to understand human brain functions. This activation-based paradigm treated underlying spontaneous brain activity, a.k.a. intrinsic activity, as noise hence irrelevant to cognitive or behavioral functions. This view, however, has been profoundly modified by the discovery that intrinsic activity is not random, but temporally correlated at rest in widely distributed spatiotemporal patterns, so called resting state networks (RSN). Studies of temporal correlation of spontaneous activity among brain regions, or functional connectivity (FC), have yielded important insights into the network organization …


Elucidating The Roles Of Astrocyte-Derived Factors In Recovery And Regeneration Following Spinal Cord Injury, Russell E. Thompson May 2019

Elucidating The Roles Of Astrocyte-Derived Factors In Recovery And Regeneration Following Spinal Cord Injury, Russell E. Thompson

McKelvey School of Engineering Theses & Dissertations

Central nervous system (CNS) injury often causes some level of long-term functional deficit, due to the limited regenerative potential of the CNS, that results in a decreased quality of life for patients. CNS regeneration is inhibited partly by the development of a glial scar following insult that is inhibitory to axonal growth. The major cell population responsible for the formation this glial scar are astrocytes, which has led to the belief that astrocytes are primarily inhibitory following injury. Recent work has challenged this conclusion, finding that astrocyte reactivity is heterogeneous and that some astrocytes are pro-regenerative following injury. Astrocyte transplantation …


Functional Electrical Stimulation Of Peripheral Nerve Tissue Via Regenerative Sieve Microelectrodes, Matthew Reagan Macewan May 2018

Functional Electrical Stimulation Of Peripheral Nerve Tissue Via Regenerative Sieve Microelectrodes, Matthew Reagan Macewan

McKelvey School of Engineering Theses & Dissertations

Functional electrical stimulation (FES) of peripheral nervous tissue offers a promising method for restoring motor function in patients suffering from complex neurological injuries. However, existing microelectrodes designed to stimulate peripheral nerve are unable to provide the type of stable, selective interface required to achieve near-physiologic control of peripheral motor axons and distal musculature. Regenerative sieve electrodes offer a unique alternative to such devices, achieving a highly stable, selective electrical interface with independent groups of regenerated nerve fibers integrated into the electrode. Yet, the capability of sieve electrodes to functionally recruit regenerated motor axons for the purpose of muscle activation remains …


Characterization Of Structural Dynamics Of The Human Head Using Magnetic Resonance Elastography, Andrew Arun Badachhape Dec 2017

Characterization Of Structural Dynamics Of The Human Head Using Magnetic Resonance Elastography, Andrew Arun Badachhape

McKelvey School of Engineering Theses & Dissertations

In traumatic brain injury (TBI), the skull-brain interface, composed of three meningeal layers: the dura mater, arachnoid mater, and pia mater, along with cerebrospinal fluid (CSF) between the layers, plays a vital role in transmitting motion from the skull to brain tissue. Magnetic resonance elastography (MRE) is a noninvasive imaging modality capable of providing in vivo estimates of tissue motion and material properties. The objective of this work is to augment human and phantom MRE studies to better characterize the mechanical contributions of the skull-brain interface to improve the parameterization and validation of computational models of TBI. Three specific aims …


Robust Odorant Recognition In Biological And Artificial Olfaction, Nalin Katta Aug 2017

Robust Odorant Recognition In Biological And Artificial Olfaction, Nalin Katta

McKelvey School of Engineering Theses & Dissertations

Accurate detection and identification of gases pose a number of challenges for chemical sensory systems. The stimulus space is enormous; volatile compounds vary in size, charge, functional groups, and isomerization among others. Furthermore, variability arises from intrinsic (poisoning of the sensors or degradation due to aging) and extrinsic (environmental: humidity, temperature, flow patterns) sources. Nonetheless, biological olfactory systems have been refined over time to overcome these challenges. The main objective of this work is to understand how the biological olfactory system deals with these challenges, and translate them to artificial olfaction to achieve comparable capabilities. In particular, this thesis focuses …


Lesion Identification And The Effect Of Lesion On Motor Mapping After Stroke, Ruixi Zhou May 2016

Lesion Identification And The Effect Of Lesion On Motor Mapping After Stroke, Ruixi Zhou

McKelvey School of Engineering Theses & Dissertations

Stroke is the most common cause of long-term severe disability and the motor system that is most commonly affected in stroke. One of the mechanisms that underlies recovery of motor deficits is reorganization or remapping of functional representations around the motor cortex. This mechanism has been shown in monkeys, but results in human subjects have been variable. In this thesis, I used a database that includes longitudinal behavioral and multimodal imaging data in both stroke patients and healthy controls for two research projects. Firstly, I improved an automatic lesion segmentation method to aid in the identification of the location and …