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Full-Text Articles in Engineering
Acute Oxygen-Sensing By The Carotid Bodies : The Thermal Microdomain Model, Ryan Joseph Rakoczy
Acute Oxygen-Sensing By The Carotid Bodies : The Thermal Microdomain Model, Ryan Joseph Rakoczy
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The carotid bodies (CB) are peripheral chemoreceptors that detect changes in arterial oxygenation and, via afferent inputs to the brainstem, correct the pattern of breathing to restore blood gas homeostasis. Elucidating the “signal” that couples carotid body sensory type I cell (CBSC) hypoxic mitochondrial inhibition with potassium channel closure has proven to be an arduous task; to date, a multitude of oxygen-sensing chemotransduction mechanisms have been described and altercated (Varas, Wyatt & Buckler, 2007; Gao et al, 2017; Rakoczy & Wyatt, 2018). Herein, we provide preliminary evidence supporting a novel oxygen-sensing hypothesis suggesting CBSC hypoxic chemotransductive signaling may in part …
Als-Induced Excitability Changes In Individual Motorneurons And The Spinal Motorneuron Network In Sod1-G93a Mice At Symptom Onset, Christiana S.I. Draper
Als-Induced Excitability Changes In Individual Motorneurons And The Spinal Motorneuron Network In Sod1-G93a Mice At Symptom Onset, Christiana S.I. Draper
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Amyotrophic lateral sclerosis (ALS) is the most common motorneuron (MN) disease in adulthood. ALS is hallmarked by the progressive loss of MNs in the brain, brainstem, and spinal cord. Many hypotheses to explain the pathogenesis of ALS have been explored, but the exact mechanisms underlying the development of this disease remain unknown. However, abnormalities in MN excitability and glutamate excitotoxicity are the most widely studied. For decades, researchers have examined MN excitability in ALS, but the current literature is inconsistent, showing evidence of hyperexcitability, hypoexcitability, or no change in excitability of MNs in ALS. Many of these studies also focus …
Observing P300 Amplitudes In Multiple Sensory Channels Using Cognitive Probing, Cody Lee Wintermute
Observing P300 Amplitudes In Multiple Sensory Channels Using Cognitive Probing, Cody Lee Wintermute
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High cognitive workload occurs when excessive working memory resources have been deployed to resolve sensory and cognitive processing, resulting in decremented task performance. The P300 event-related potential (ERP) component has shown sensitivity to cognitive load, and it was hypothesized that an attenuated P300 amplitude could be indicative of high cognitive load. We tested this hypothesis by having eight participants complete two continual performance tasks at increasing workload levels while simultaneously performing an oddball task, evoking P300 ERPs in either the auditory or tactile sensory channel. In our experiment, electroencephalographic recordings were collected over the parietal region to observe the P300 …
Kv2.1 Channel Clustering In The Sod1-G93a Mouse Model Of Als, Joshua Christopher Harris
Kv2.1 Channel Clustering In The Sod1-G93a Mouse Model Of Als, Joshua Christopher Harris
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Kv2.1 channels mediate slow-activating K+ rectifier current within the membrane of spinal motoneurons (MNs), and they are known to co-localize with other synapses and ion channels. Although Kv2.1 channels are suggested to regulate MN excitability, little research has gone into investigating its potential contribution to MN-altered excitability in Amyotrophic Lateral Sclerosis (ALS). Using the male SOD1-G93A mouse model of ALS, we examined Kv2.1 cluster area and density in lumbar MNs at four key stages of disease progression. In our experiments, MNs were separated by type via SK3 immunoreactivity in order to isolate and compare the responses of disease-resistant (slow; SK3+) …
Visual Sampling With The Eeg Alpha Oscillation, Kevin Eugene Alexander
Visual Sampling With The Eeg Alpha Oscillation, Kevin Eugene Alexander
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The posterior alpha rhythm, seen in human electroencephalograms (EEG), is posited to originate from cycling inhibitory/excitatory states of visual relay cells in the thalamus, which could result in discrete sampling of visual information. Here, we tested this hypothesis by presenting light flashes at perceptual threshold intensity through closed eyelids to 20 participants during times of spontaneous alpha oscillations. Alpha phase and amplitude were calculated relative to each individual’s retina-to-V1 conduction delay, estimated by the individuals’ C1 visual-evoked potential latency. Our results show that an additional 20.96% of stimuli are observed when afferenting at V1 during an alpha wave trough (272.41°) …
Development Of An Astrocyte/Glioma Co-Culture System For Measuring Cellular Dynamics, Urna Kansakar
Development Of An Astrocyte/Glioma Co-Culture System For Measuring Cellular Dynamics, Urna Kansakar
Doctoral Dissertations
Gliomas are brain tumors that primarily arise from glial cells. Gliomas account for 70% of the brain tumors and they are more prevalent in older adults. About 60% of the people with gliomas experience at least one seizure. Brain tumors can grow and metastasize to neighboring areas, thereby destroying normal brain cells. In a brain tumor microenvironment, both malignant cancer cells and healthy brain cells are present. Studies have shown that astrocytes may have a role in tumor growth in the brain. Monocultures cannot evaluate interactions between two cell types and does not accurately represent in vivo conditions. Thus, a …
Three-Dimensional Human Neural Stem Cell Culture For High-Throughput Assessment Of Developmental Neurotoxicity, Pranav Joshi
Three-Dimensional Human Neural Stem Cell Culture For High-Throughput Assessment Of Developmental Neurotoxicity, Pranav Joshi
ETD Archive
Only a few hundred of compounds, among tens of thousands of commercially available compounds, have been tested for developmental neurotoxicity (DNT) due to the limitations of current guidelines for DNT which are based entirely on in vivo experiments. In vivo studies are highly expensive and time-consuming, which often do not correlate to human outcomes. There is a key gap in our ability to predict in vivo outcomes accurately and robustly using in vitro assays. This is particularly the case for predicting the toxicity of chemicals on the developing human brains. Conventional in vitro assays are typically performed in two-dimensional (2D) …
Type 2 Diabetes Leads To Impairment Of Cognitive Flexibility And Disruption Of Excitable Axonal Domains In The Brain, Leonid M. Yermakov
Type 2 Diabetes Leads To Impairment Of Cognitive Flexibility And Disruption Of Excitable Axonal Domains In The Brain, Leonid M. Yermakov
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Type 2 diabetes is a metabolic disease affecting millions of people around the world. Cognitive and mood impairments are among its many debilitating complications, but disease mechanism(s) remain elusive. Here, we present a series of behavioral tasks that demonstrate impairment of cognitive flexibility in db/db mice, a commonly used type 2 diabetes model. Using immunohistochemistry, we demonstrate disruption of axon initial segments (AIS) and nodes of Ranvier, excitable axonal domains regulating neuronal output, in brain regions associated with cognitive and mood impairments. Finally, we present results of exercise treatment that ameliorates AIS disruption in these animals. Establishing cognitive flexibility deficits …
Biomarker-Performance Associations During Nutritional And Exercise Intervention In Air Force Personnel, Jennifer Jurcsisn
Biomarker-Performance Associations During Nutritional And Exercise Intervention In Air Force Personnel, Jennifer Jurcsisn
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This study evaluated the combined effects of an exercise intervention and nutritional supplement on biomarkers of stress and resilience, and the relationships of those markers with physical and cognitive performance. 130 healthy Active-Duty Air Force (AF) personnel were recruited to participate in a double-blind, placebo controlled 12-week exercise and nutritional intervention. Serum was collected at basal and high stress conditions pre- and post-intervention to track the following biomarkers: cortisol, dehydroepiandrosterone-sulfate (DHEA-S), norepinephrine (NE), neuropeptide Y (NPY), and serotonin. The exercise intervention significantly attenuated the cortisol response and peak stress cortisol levels. The nutritional intervention decreased peak stress NE. The selected …
Divergent Scaling Of Miniature Excitatory Post-Synaptic Current Amplitudes In Homeostatic Plasticity, Amanda L. Hanes
Divergent Scaling Of Miniature Excitatory Post-Synaptic Current Amplitudes In Homeostatic Plasticity, Amanda L. Hanes
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Synaptic plasticity, the ability of neurons to modulate their inputs in response to changing stimuli, occurs in two forms which have opposing effects on synaptic physiology. Hebbian plasticity induces rapid, persistent changes at individual synapses in a positive feedback manner. Homeostatic plasticity is a negative feedback effect that responds to chronic changes in network activity by inducing opposing, network-wide changes in synaptic strength and restoring activity to its original level. The changes in synaptic strength can be measured as changes in the amplitudes of miniature post-synaptic excitatory currents (mEPSCs). Together, the two forms of plasticity underpin nervous system functions such …
Neural Correlates Of Convergence Eye Movements In Convergence Insufficiency Patients Vs Normal Binocular Vision Controls: An Fmri Study, Chirag Bharatkumar Limbachia
Neural Correlates Of Convergence Eye Movements In Convergence Insufficiency Patients Vs Normal Binocular Vision Controls: An Fmri Study, Chirag Bharatkumar Limbachia
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Convergence Insufficiency is a binocular vision disorder, characterized by reduced ability of performing convergence eye movements. Absence of convergence causes, eye strain, blurred vision, doubled vision, headaches, and difficulty reading due frequent loss of place. These symptoms commonly occur during near work. The purpose of this study was to quantify neural correlates associated with convergence eye movements in convergence insufficient (CI) patients vs. normal binocular vision (NBV) controls, and to examine statistical differences between them. Functional magnetic resonance imaging (fMRI) scans were collected using a 3T Siemens scanner. A disparity-driven convergence task was designed using a standard block design approach, …
Regulation Of Motoneuron Firing Properties: Intrinsic And Circuit-Based Mechanisms, Adam S. Deardorff
Regulation Of Motoneuron Firing Properties: Intrinsic And Circuit-Based Mechanisms, Adam S. Deardorff
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Body and limb movements are controlled by regulating the activity of motor pools and their constituent motoneurons. An extensive complement of tightly regulated ion channels and second messenger systems determine active motoneuron spiking behavior, while segmental propriospinal circuits ensure the faithful execution of motor commands by providing real time sensory feedback to motoneurons and other somatosensory centers. However, current mechanistic understanding is incomplete for critical factor regulating motoneuron firing properties. Fundamental gaps in knowledge exist regarding (a) the spatial distribution and organization of specific ion channels in motoneurons, (b) the contribution of specific channels to motoneuron intrinsic properties, (c) the …
Segmentation And Analysis Of Mris Of Infants With Dysphagia, Irfaan A. Dar
Segmentation And Analysis Of Mris Of Infants With Dysphagia, Irfaan A. Dar
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Neonates are at a rapid stage of development from birth throughout childhood. Impairments to certain cortical areas can result in long lasting neuro-cognitive dysfunctions. Disorders to the swallowing neural pathways can have detrimental effects throughout life course since methods to provide nutrition can be comprised. Dysphagia, or the inability to swallow, can be caused by a multitude of reasons, chiefly neurological, but the underlying disruptions to the neural pathways are not defined. In this study we investigated the growth of multiple cortical areas involved in the swallowing pathway and categorized feeding outcomes with neural growth. Results showed that infants that …
A Robotic Neuro-Musculoskeletal Simulator For Spine Research, Robb W. Colbrunn
A Robotic Neuro-Musculoskeletal Simulator For Spine Research, Robb W. Colbrunn
ETD Archive
An influential conceptual framework advanced by Panjabi represents the living spine as a complex neuromusculoskeletal system whose biomechanical functioning is rather finely dependent upon the interactions among and between three principal subsystems: the passive musculoskeletal subsystem (osteoligamentous spine plus passive mechanical contributions of the muscles), the active musculoskeletal subsystem (muscles and tendons), and the neural and feedback subsystem (neural control centers and feedback elements such as mechanoreceptors located in the soft tissues) [1]. The interplay between subsystems readily encourages "thought experiments" of how pathologic changes in one subsystem might influence another--for example, prompting one to speculate how painful arthritic changes …