Neuroscience and Neurobiology Commons^™

Effects Of Moderate-Level Sound Exposure On Behavioral Thresholds In Chinchillas, Maria Sandra Carbajal De Nava

Open Access Theses

Normal audiometric thresholds following noise exposure have generally been considered as an indication of a recovered cochlea and intact peripheral auditory system, yet recent animal work has challenged this classic assumption. Moderately noise-exposed animals have been shown to have permanent loss of synapses on inner hair cells (IHCs) and permanent damage to auditory nerve fibers (ANFs), specifically the low-spontaneous rate fibers (low-SR), despite normal electrophysiological thresholds. Loss of cochlear synapses, known as cochlear synaptopathy, disrupts auditory-nerve signaling, which may result in perceptual speech deficits in noise despite normal audiometric thresholds. Perceptual deficit studies in humans have shown evidence consistent with …

Optimizing The Neural Response To Electrical Stimulation And Exploring New Applications Of Neurostimulation, Kurt Yuqin Qing

Open Access Dissertations

Electrical stimulation has been successful in treating patients who suffer from neurologic and neuropsychiatric disorders that are resistant to standard treatments. For deep brain stimulation (DBS), its official approved use has been limited to mainly motor disorders, such as Parkinson's disease and essential tremor. Alcohol use disorder, and addictive disorders in general, is a prevalent condition that is difficult to treat long-term. To determine whether DBS can reduce alcohol drinking in animals, voluntary alcohol consumption of alcohol-preferring rats before, during, and after stimulation of the nucleus accumbens shell were compared. Intake levels in the low stimulus intensity group (n=3, 100&mgr;A …

The Pathological Role Of Acrolein In Experimental Autoimmune Encephalomyelitis And Multiple Sclerosis, Melissa A. Tully

Open Access Dissertations

Multiple sclerosis (MS) is an autoimmune demyelinating neuropathy that affects nearly 2.5 million people worldwide. Despite substantial efforts, few treatments are currently available largely due to limited knowledge of pathogenic mechanisms underlying the disease. The immune-inflammatory nature of the pathology has prompted investigation of the role of oxidative stress in disease development and progression; however targeting reactive oxygen species for neutralization has had marginal success therapeutically, suggesting that an alternate oxidative stress-related target would prove beneficial. Recently, our lab has implicated acrolein, a highly reactive aldehyde that is both a byproduct and catalyst of lipid peroxidation, as a potential therapeutic …

Elucidation Of Pharmacologically Manipulated Responding In The Delay Discounting Task In High Alcohol Preferring Mice, Meredith Halcomb

Open Access Dissertations

Impulsive behavior is the hallmark of many psychopathologies. Uncovering the neurobiological mechanisms driving impulsivity is paramount in the development of through the delay discounting (DD) task in both human and animal models. The present study is an examination of the predictive validity of the two primary types of DD procedures in animals, the Adjusting Amounts (AA) and within session Increasing Delays (ID) tasks. Methods:Subjects were administered either1.25 mg/kg d-amphetamine (AMP), 1.5 g/kg ethanol (EtOH) or saline and tested in either the AA or ID method for 15 days to evaluate drug effects on impulsive behavior. Results: Stimulant administration resulted …

Developing A Practical Wireless Monitoring Solution For A Size-Constrained, Low-Power, Biomechanical, Sports Telemetry System, Jeffery Ray King

Open Access Theses

As sport-related concussions become more prevalent, the ability to quickly and reliably assess brain injury risk is increasingly essential. Commercially-available systems exist with the goal of assessing the risk of traumatic brain injury in athletes in real-time. These systems utilize a pre-determined acceleration threshold, discarding all captured information below this arbitrary threshold. The use of an event-based model to assess the risk of traumatic brain injury has been shown to be inadequate. Therefore, these systems falsely promote "accurate" real-time communication of risk. Research conducted by the Purdue Neurotrauma Group (PNG) seeks to advance the field by developing a biomechanical sports …

Quantitative Modeling Of Spatiotemporal Systems: Simulation Of Biological Systems And Analysis Of Error Metric Effects On Model Fitting, James Hengenius

Open Access Dissertations

Understanding the biophysical processes underlying biological and biotechnological processes is a prerequisite for therapeutic treatments and technological innovation. With the exponential growth of computational processing speed, experimental findings in these fields have been complemented by dynamic simulations of developmental signaling and genetic interactions. Models provide means to evaluate "emergent" properties of systems sometimes inaccessible by reductionist approaches, making them test beds for biological inference and technological refinement.^ The complexity and interconnectedness of biological processes pose special challenges to modelers; biological models typically possess a large number of unknown parameters relative to their counterparts in other physical sciences. Estimating these parameter …

Acrolein As A Novel Therapeutic Target For Spinal Cord Injury Induced Neuropathic Pain, Jonghyuck Park

Open Access Dissertations

Despite years of research, post-spinal cord injury (SCI) chronic neuropathic pain remains refractory to treatment and drastically impairs quality of life for SCI victims beyond paralysis. Although inflammation and free radicals contribute to neuropathic pain in SCI, the mechanism is not completely clear. We have recently demonstrated that acrolein, a product and catalyst of lipid peroxidation, induces a vicious cycle of oxidative stress, amplifying its effects and perpetuating oxidative stress and inflammation. In the current study, we have confirmed that acrolein is elevated significantly at least two weeks post-SCI which coincides with the emergence of hyperalgesia (mechanical, cold and thermal). …

Morphometric Characterization Of Individual Sympathetic Postganglionic Axons Innervating The Muscle Layers Of The Gastrointestinal Tract Of The Rat: A Complex Effector Model, Gary C. Walter

Open Access Dissertations

A full description of the terminal morphology of sympathetic postganglionic axons innervating the musculature of the gastrointestinal (GI) tract has not been available. Furthermore, common assumptions about the morphology and distribution of catecholaminergic terminal fields have been strongly shaped by the limitations of the techniques employed to distinguish the fibers and complicated by inconsistent findings generated with various methodologies. Thus, the present experiment used modern neural tracer techniques to provide high-resolution labeling of sympathetic fibers projecting to the smooth muscle wall of the GI tract. Fischer 344 rats (N = 50) received injections of dextran biotin into the left …

Nano-Engineered Polymers In Drug Delivery: Potential Approaches For Attenuation Of Secondary Injury After Spinal Cord Trauma, Wen Gao

Open Access Dissertations

Secondary injury elicits a complex series of pathophysiological events after the primary spinal cord trauma and even after its implantation treatment for neural functional recovery. These secondary injuries include an up-regulation of glial cells associated reactive oxygen species, nitrogen species, and reactive astrogliosis, and they can result in various levels of cellular and tissue damage. The inhibition of them has been proved to lead to functional recovery of the spinal cord. In this study, we concentrated on developing polymers and nano-techniques based drug delivery strategies to eliminate these secondary injuries. ^ To maintain and improve the performance of the implants …

Particle Swarm Optimization Using Multiple Neighborhood Connectivity And Winner Take All Activation Applied To Biophysical Models Of Inferior Colliculus Neurons, Brandon S. Coventry

Open Access Theses

Age-related hearing loss is a prevalent neurological disorder, affecting as many as 63% of adults over the age of 70. The inability to hear and understand speech is a cause of much distress in aged individuals and is becoming a major public health concern as age-related hearing loss has also been correlated with other neurological disorders such as Alzheimer's dementia. The Inferior Colliculus (IC) is a major integrative auditory center, receiving excitatory and inhibitory inputs from several brainstem nuclei. This complex balance of excitation and inhibition gives rise to complex neural responses, which are measured in terms of firing rate …

Lipidomic Analysis Of Glioblastoma Multiforme, Soo Jung Ha

Open Access Theses

Glioblastoma Multiforme (GBM) is the most common and malignant form of the primary brain tumor. Due to its highly invasive nature, current treatment options have not been able to improve the survival rate in past 20 years. In order to discover GBM therapeutic targets, omics technologies have been widely used to identify potential biomarkers. ^ This research study focused on investigating lipid biomarkers of human GBM orthotopic mouse models employing mass spectrometry. Human tumor cell lines GBM10 and GBM43 were injected in the right cerebral hemisphere and flank sites in NOD/SCID mice (n = 10 mice per group). Left cerebral …

Analysis Of Neuronal And Microglial Responses To Implanted Silicon Devices Through Immunohistochemistry And Clarity, Michael A. Leathers, Kevin J. Otto

The Summer Undergraduate Research Fellowship (SURF) Symposium

Brain computer interfaces (BCI’s) and implantable cortical devices have recently emerged in research as promising treatment methods for a variety of neurological problems such as motor dysfunction, memory loss, and sudden onset seizures. The number of people currently suffering from a loss of nervous system function as a result of neurodegenerative diseases or injury creates a need for reliable neural prostheses. The autoimmune response of the Central Nervous System (CNS) when introduced with a foreign object such as an electrode shank quickly impedes signal strength and degrades the functional life of the device. Two different experimental methods were used to …

Reasoning Across Language And Vision In Machines And Humans, Andrei Barbu

Open Access Dissertations

Humans not only outperform AI and computer-vision systems, but use an unknown computational mechanism to perform tasks for which no suitable approaches exist. I present work investigating both novel tasks and how humans approach them in the context of computer vision and linguistics. I demonstrate a system which, like children, acquires high-level linguistic knowledge about the world. Robots learn to play physically-instantiated board games and use that knowledge to engage in physical play. To further integrate language and vision I develop an approach which produces rich sentential descriptions of events depicted in videos. I then show how to simultaneously detect …

Effects Of Dip-Coated Films On The Properties Of Implantable Intracortical Microelectrodes, Salah Sommakia

Open Access Dissertations

The successful clinical use of implantable intracortical microelectrodes (ICMs) to treat certain types of deafness, blindness, and paralysis is limited by a reactive tissue response (RTR) of the brain. This RTR culminates in the formation of a tight glial scar and a loss of neuronal density around implanted ICMs, and is accompanied by a decrease in signal to noise ratio and an increase in impedance. While no comprehensive mechanistic understanding of the underlying biology is currently agreed upon in the field, a general consensus exists around a highly volatile acute RTR phase. During this acute phase, the electrical properties of …

Smooth Muscle-Specific Removal Of Brain-Derived Neurotrophic Factor Results In Increased Vagal Afferent Innervation To The Intestine And Increased Satiation In Mice, Jessica Erin Biddinger

Open Access Dissertations

Vagal afferents transmit signals regarding food-derived stimuli in the gastrointestinal (GI) tract to the brain. Vagal mechanoreceptors called intraganglionic laminar endings (IGLEs) innervate the smooth muscle wall of GI organs and detect stretch and tension to regulate GI reflexes and satiation. Brain-derived neurotrophic factor (BDNF) is expressed in the smooth muscle of developing GI organs when vagal afferents from the nodose ganglion begin to innervate the GI tract. Therefore, it was hypothesized BDNF is necessary for development of vagal afferents that innervate this tissue. Targeted smooth muscle-specific BDNF homozygous knockout (BDNF SM -/-) mice were generated and .vagal afferent innervation …

Effects Of Hearing Aid Amplification On Robust Neural Coding Of Speech, Jonathan Daniel Boley

Open Access Dissertations

Hearing aids are able to restore some hearing abilities for people with auditory impairments, but background noise remains a significant problem. Unfortunately, we know very little about how speech is encoded in the auditory system, particularly in impaired systems with prosthetic amplifiers. There is growing evidence that relative timing in the neural signals (known as spatiotemporal coding) is important for speech perception, but there is little research that relates spatiotemporal coding and hearing aid amplification.

This research uses a combination of computational modeling and physiological experiments to characterize how hearing aids affect vowel coding in noise at the level of …

Neuroprotection By Chitosan And Chitosan Nanoparticles, Bojun Chen

Open Access Dissertations

In the U.S., about 200,000 people are currently living with spinal cord injury (SCI). An estimated of 50%-70% of all SCI cases occurs in the range of ages between 15-35 years old. The destructive neurotrauma results in the majority of adult disability, even after patients suffering with SCI survived from the acute death. There are two stages involved in the progression of SCI, the primary stage and the secondary stage. The primary stage is mainly the mechanical damage to the central nervous system. The rapid collapse of the integrity of cell membrane and tissue is often one of the initial …