Life Sciences Commons^™

Effects Of Testosterone On The Spatial Ecology, Coloration, And Brain Regions In Western Fence Lizards, Sceloporus Occidentalis, Rachel Catharine Wilson

Master's Theses

An organism’s spatial ecology allows for access to essential resources such as food, mates, and escape from predators. Home range size, or the total area an organism inhabits, varies in relation to numerous factors including seasonality. During the breeding season, home range size increases in males across taxa. In addition, males usually also have larger home range sizes than females. This implicates testosterone (T) as a possible mediator of this relationship. Indeed, T causes an increase in home range size of males in numerous species of lizards. In addition to T causing an increase in home range size, it also …

Developing A Contrast Agent For The In Vivo Detection Of Apoptosis, Mary R. Cobb

Electronic Thesis and Dissertation Repository

Currently, there is no way to assess apoptotic cell death in living organisms. We have developed a novel contrast agent targeted toward the detection of caspase-3 activity, the key enzymatic mediator of apoptosis. Our contrast agent consists of a dual magnetic resonance imaging/fluorescent probe coupled to a cell penetrating peptide (CPP) sequence by a peptide backbone containing a caspase-3 cleavage site. The CPP allows the agent to cross cell membranes and the blood brain barrier. In cells undergoing apoptosis, activated caspase-3 will cleave the agent removing the CPP and trapping the imaging probes inside the cell.

The purpose of this …

Interactions Between The Hypothalamic-Pituitary-Adrenal (Hpa) Axis, Oxytocin System, And Behavior In Differently Reared Rhesus Monkeys (Macaca Mulatta), Amanda F. Hamel

Doctoral Dissertations

Adverse experiences that occur during early critical periods of development modify activity of neuroendocrine systems, such as the hypothalamic-pituitary-adrenal (HPA) axis and oxytocin system. This dissertation examines the effects of nursery rearing, an established model of adverse early experiences, on activity of the HPA axis and oxytocin system in infant and adult rhesus macaques (Macaca mulatta). In addition, influence of oxytocin system activity on the HPA axis and behavioral reactivity was examined. In infant monkeys, nursery-rearing was associated with lower HPA axis, yet higher oxytocin system activity, following the acute stress of developmental assessment. Nursery rearing may result …

Estrogen-Sensitive Learning Is Not Affected By Combination Ethinyl Estradiol And Levonorgestrel Oral Contraceptive Use, Darlene F. Ficco

Doctoral Dissertations

Two studies were conducted to explore the cognitive effects of combination ethinyl estradiol and levonorgestrel contraceptive use during late adolescence and young adulthood. Three groups of females, naturally cycling, active pill phase, and hormone-free interval phase, were tested on a battery of estrogen-sensitive, i.e., place learning and word generation, and estrogen-insensitive, i.e., map drawing, mental rotation, digit span, story recall, and object recall, tasks. Study 2 was conducted as a means to replicate the findings observed in Study 1 and to manipulate task difficulty and sensitivity. Two measures of mood were administered, and salivary estradiol levels at time of testing …

Co-Morbidity Of Alzheimer’S Disease And Stroke: Cognitive Deficits And Cellular Pathologies In Two Co-Morbid Animal Models, Jennifer L. Au

Electronic Thesis and Dissertation Repository

Prior to beta-amyloid (Aβ) protein accumulation into plaques in Alzheimer’s disease (AD), neuroinflammation and oxidative stress have been shown to contribute to early cognitive decline. These cellular pathologies are coincident in stroke, which is considered a risk factor for AD. This study investigated the co-morbid effects of AD and stroke on behavioural and cellular pathology in two rodent models. Motor function, memory and microglial neuroinflammation were investigated in a stroke and Aβ injection model and mutant human amyloid precursor protein (APP) transgenic model with stroke. Injections of endothelin-1 into the right striatum were used to model stroke and AD was …

Hierarchical Organization In Auditory Cortex Of The Cat Using High-Field Functional Magnetic Resonance Imaging, Amee J. Hall

Electronic Thesis and Dissertation Repository

Sensory localization within cortex is a widely accepted and documented principle. Within cortices dedicated to specific sensory information there is further organization. For example, in visual cortices a more detailed functional division and hierarchical organization has been recorded in detail. This organization starts with areas dedicated to analysis of simple visual stimuli. Areas higher in the organization are specialized for processing of progressively more complex stimuli. A similar hierarchical organization has been proposed within auditory cortex and a wealth of evidence supports this hypothesis. In the cat, the initial processing of simple auditory stimuli, such as pure tones, has been …

Muscarinic Attenuation Of Mnemonic Rule Representation In Macaque Dorsolateral Prefrontal Cortex During A Pro- And Anti-Saccade Task, Alex J. Major

Electronic Thesis and Dissertation Repository

Maintenance of context is necessary for execution of appropriate responses to diverse environmental stimuli. The dorsolateral prefrontal cortex (DLPFC) plays a pivotal role in executive function, including working memory and representation of abstract rules, and is modulated by the ascending cholinergic system through nicotinic and muscarinic receptors. Muscarinic receptors’ effect on local primate DLPFC neural activity in vivo during cognitive tasks remains poorly understood. Here we examined the effects of muscarinic receptor blockade on rule-related activity in the macaque prefrontal cortex by combining iontophoretic application of the general muscarinic receptor antagonist scopolamine with single-unit recordings while monkeys performed a rule-guided …

Relationships Between Age And White Matter Integrity In Children With Phenylketonuria, Erika M. Wesonga

Arts & Sciences Electronic Theses and Dissertations

Objective: Phenylketonuria (PKU) is a hereditary metabolic disorder associated with cognitive compromise. Diffusion tensor imaging (DTI) has allowed detection of poorer microstructural white matter integrity in children with PKU, with decreased mean diffusivity (MD) in comparison with healthy children. However, very little research has been conducted to examine the trajectory of white matter development in this population. The present study investigated potential differences in the developmental trajectory of MD between children with early- and continuously-treated PKU and healthy children across a range of brain regions.

Methods: Children with PKU (n = 31, mean age = 12.2 years) were …

Characteristics Of Exocytosis And Endocytosis In Photoreceptors, Karlene M. Cork

Theses & Dissertations

Photoreceptors signal changes in light intensity to downstream retinal neurons through the exocytosis of glutamate-containing synaptic vesicles. The maintenance of the vesicle exocytosis and endocytosis process is essential for ongoing synaptic signaling. This study investigated the properties of exocytosis and endocytosis in photoreceptors and their role in ongoing neurotransmission.

I used electrophysiology and imaging techniques to study the properties of vesicle exocytosis and endocytosis in photoreceptors. First, we examined baseline release in photoreceptors that occurs in the absence of depolarizing stimulation. We measured mEPSCs in whole cell patch clamp recordings from horizontal cells. After inhibiting Ca²⁺ influx and efflux …

Effects Of Maternal Immune Activation And Repeated Maternal Separation On Postpartum Behaviors In The Female Rat Offspring, Shinnyi Chou

Theses & Dissertations

Early life stress can induce persistent brain and behavioral alterations. As a lifetime history of clinical symptoms similar to those caused by early adversities may predict postpartum dysfunctions, these stressors likely contribute to their etiology. Postpartum neuropsychiatric disorders (e.g. postpartum depression, anxiety and depression) are costly, yet due to the complex neuronal reorganization during this period, insights into how early adversities-induced CNS functional changes affect postpartum processes remain limited, especially under multiple stressors. Thus, there is a need to determine postpartum functions altered by early stress, in order to increase understandings of risks associated with postpartum maladaptations. Accordingly, this work …

Microengineering The Neural Tube, Christopher Demers

Electronic Theses and Dissertations

Early embryonic development is a complex and highly regulated orchestra of instructive cues that collectively guide naïve stem cells towards progressively more specialized fates. In the neural tube, the precursor structure to the brain and spinal cord, these signals emanate from ‘organizing centers’ surrounding the neural tube. These organizing centers send out soluble cues or morphogens that diffuse tens to hundreds of microns to recipient cells residing in the neural tube. Re-creating this dynamic landscape of cues in vitro is impossible using standard cell culture tools and techniques. However, microfluidics is perfectly suited to fill this gap, allowing precise control …

Canonical Bmp Signaling Is Required For Allodynia In Drosophila Melanogaster, Taylor L. Follansbee

All Theses And Dissertations

In the United States alone over 100 million people suffer from chronic pain and unfortunately, even still, there is a lack in scientific understanding for the mechanisms of abnormal pain sensitivity. The present study utilized a candidate gene approach to identify novel components required for modulation of the tissue damage induced pain sensitization pathway in Drosophila melanogaster. We have shown that RNAi silencing of decapentaplegic (dpp), a member of the Bone Morphogenetic Protein (BMP) signaling pathway, specifically in the class IV multidendritic nociceptor neurons significantly attenuated UV-induced nociceptive sensitization. Furthermore, overexpression of dpp in nociceptor neurons was sufficient to …

Hippocalcin Response To Calcium: Do Conserved Tryptophans – W30 Or W103 – Matter?, Sunkesula K. Sagar

Graduate School of Biomedical Sciences Theses and Dissertations

Changes in intracellular calcium levels play a very important role in cell signaling, in turn, affecting neuronal functions such as memory, learning and cell death. A class of proteins called Neuronal Calcium Sensor (NCS) proteins serves to modulate the functioning of the neuronal cells in response to changes in calcium levels, and prevent neuronal apoptosis. Structurally, all NCS proteins have 4 calcium-binding EF hand motifs, although EF1 does not bind to calcium in many members. All NCS proteins have an acyl modification at the N- terminus – where a myristoyl group is added post-translationally. Hippocalcin (HPCA) is an NCS protein, …

Relationship Between Learning-Related Synaptic And Intrinsic Plasticity Within Lateral Amygdala, Megha Sehgal

Theses and Dissertations

A central question in neuroscience is to determine the mechanisms that govern formation, storage and modulation of memories. Determining these mechanisms would allow us to facilitate new memory formation as in the case of aging-related cognitive decline or weaken preexisting pathological memories such as traumatic memories and cue-induced drug craving. Pharmacological and genetic manipulation of intrinsic neuronal excitability has been demonstrated to impact the strength of memory formation, allocation of memories, and modulation of memories through retrieval and reconsolidation-dependent processes. In addition to experimental manipulations of intrinsic excitability, intrinsic plasticity, a change in neuronal intrinsic excitability, can be brought about …

An Analysis Of The Interaction Of Methylphenidate And Nicotine In Adolescent Rats: Effects On Bdnf, Elizabeth D. Freeman

Electronic Theses and Dissertations

This investigation was an analysis of the interaction of adolescent exposure to methylphenidate (MPH; trade name: Ritalin) on nicotine sensitization and conditioned place preference (CPP) in a rodent model and underlying mechanisms of this effect. Animals were treated IP with 1 mg/kg MPH or saline using a ―school day‖ regimen of five days on, two days off, from postnatal day (P) 28-50. During the final two weeks of MPH treatment, animals were either behaviorally sensitized to nicotine (0.5 mg/kg free base) or saline for 10 days, or conditioned to nicotine or saline using the CPP behavioral paradigm. In addition, three …

Structure And Composition Of Postsynaptic Densities, Madeline Farley

Dissertations & Theses (Open Access)

Communication between neurons within the brain occurs at chemical synapses and is fundamental for all brain functions. Modulation of the strength of communication is controlled by both presynaptic and postsynaptic mechanisms and is termed synaptic plasticity. One postsynaptic structure postulated to regulate synaptic strength is the postsynaptic density (PSD), a large electron dense protein complex located just below the synaptic membrane. The PSD, which is composed of signaling, scaffold and cytoskeletal proteins, supports and organizes neurotransmitter receptors within the synaptic membrane in addition to bridging signaling with the actin cytoskeletal network. The protein composition and structure of PSDs is known …

The Effect Of Sleep On Perceptual Learning And Memory Consolidation, Vanessa Claire Irsik

UNLV Theses, Dissertations, Professional Papers, and Capstones

An ability to segregate speech accurately is essential given that most auditory environments contain other overlapping conversations or environmental noise. While perceiving speech among background noise can be difficult in and of itself, those with hearing impairments can experience considerable difficulty. While training has been shown to benefit perceptual segregation of trained sounds, it is unclear how such training transfers to sounds not included in a training regimen. The current study aimed to address this question by training listeners on a portion of sounds during a vowel segregation task, and subsequently testing on both the trained sounds and untrained sounds. …

The Effects Of 830nm Light On Inflammation In Retinitis Pigmentosa, Krystal Marie Bach

Theses and Dissertations

Purpose: Retinitis Pigmentosa (RP) is an inherited retinal degenerative disease and the most common cause of blindness in developed countries, affecting approximately 1 in 4,000 people. RP is characterized by photoreceptor cell death and recent studies suggest that chronic inflammation may play a key role in the pathogenesis of RP. Currently, there are no known treatments or preventive measures to delay or halt the loss of photoreceptor cells. Photobiomodulation (PBM) by light in the far-red or near-infrared (NIR) range of the light spectrum has been documented to help promote cell survival and reduce inflammation in several disease states. Recent studies …

Quantifying The Effects Of Systematic Stn-Dbs Programming On Rest And Postural Tremor In Idiopathic Parkinson Disease Patients, Kristina Ognjanovic

Electronic Thesis and Dissertation Repository

Parkinson’s disease (PD) is a complex neurodegenerative disorder that encompasses both motor and non-motor symptoms. These symptoms and their severity are typically assessed by scale based measures in a clinical setting. Scale- based assessments of PD patients undergoing bilateral subthalamic nucleus deep brain stimulation surgery (STN-DBS) such as the Unified Parkinson Disease Rating Scale (UPDRS) are commonly used in a clinical setting to assess symptom severity and progression. However, the subjective nature of these and other clinical scales call into question both the sensitivity and accuracy of patient assessment over time. An objective quantification of rest and postural tremor of …

Associations Between Anxiety And Attention In Laboratory-Housed Rhesus Macaques (Macaca Mulatta), Lauren E. Hobbs

Masters Theses

Previous studies completed with humans have revealed insight into the effects of anxiety on attention tasks such the dot-probe task, but there is little information about such effects on non-human primates. This study aimed to assess whether anxiety or anxious behaviors would impact rhesus macaque performance on a three stimuli paradigm similar to the dot-probe task. Utilizing images of conspecifics (strong threat, mild threat, and neutral), eight monkeys were video recorded completing a task that required them to slide two doors, which held these images, to the side to obtain a treat. We hypothesized that behavioral phenotype (high or low …

Contribution Of The Dorsolateral Prefrontal Cortex To Attentional And Mnemonic Processes In Visual Search, Brandon Belbeck

Electronic Thesis and Dissertation Repository

A key characteristic of selective visual attention is that it may be deployed on the basis of our knowledge or goals of the task at hand. Here, we used cryogenic deactivation to investigate the contribution of the dorsolateral PFC to cognitive flexibility and working memory, as well as their relation to the deployment of attention. Macaque monkeys performed visual search tasks requiring them to foveate a target in an array of stimuli. These included a feature search, a constant-target conjunction search, a variable-target search and variable-target with delay search task, with each being more cognitively demanding than the last. Bilateral …

Modulation Of Synaptic Plasticity By Hippocampal Theta Rhythm, Clayton Law

Electronic Thesis and Dissertation Repository

The hippocampal theta rhythm facilitates memory formation. This study investigated the temporal relation of long-term potentiation (LTP) with the hippocampal theta rhythm. Theta rhythm consists of a wave of somatodendritic depolarization, but the depolarization of apical and basal dendrites of hippocampal CA1 pyramidal cells peak at a similar theta phase. Thus, we hypothesize that the population spike excitability evoked by excitation of the apical and basal dendrites peak at a similar phase of the theta rhythm. We also expect that LTP at the basal and apical dendritic synapses to be maximal at a similar theta phase.

Rats (~300 g) were …

Susceptibility Of Parkinson’S Disease Following Mild Blast Traumatic Brain Injury, Glen Howel Galicia Acosta

Open Access Theses

Blast injury-induced neurotrauma (BINT) is steadily increasing in prevalence due to escalated terror activity and constitutes the signature injury associated with current military conflicts. BINT produces significant neurological deficiencies and there is a growing concern that the injury may produce long-term consequences that affect the resilience and the performance of soldiers. One of the potential consequences is an increased susceptibility to Parkinson's disease (PD). A vital goal aimed at curtailing the post-deployment long-term consequences of blast injury-induced neurotrauma is to further our knowledge of pathogenic mechanisms responsible for the escalation of post injury diseases. The purpose of this project is …

Spatiotemporal Fluctuations Of Olfactory Stimuli And Its Detection By An Optical Method, Mitu Chandra Acharjee

Graduate Theses and Dissertations

Olfactory processing in the mammalian brain is a highly dynamic process, yet most of the olfaction experiments have been studied primarily with static stimuli. Odors in the natural environment are transported by turbulent flow of air or water. Natural odorants have fluctuations in concentration and it changes rapidly with time. These rapid fluctuations may pose some challenges to identifying an odor; on the other hand, the variation itself may provide important clues about the odor source. The goal of this thesis project was to create a similar odorant environment like the rapid odor fluctuations encountered in nature – to meet …

A Kinematic Analysis Of Visual And Haptic Contributions To Precision Grasping In A Patient With Visual Form Agnosia And In Normally-Sighted Populations, Robert Whitwell

Electronic Thesis and Dissertation Repository

Skilled arm and hand movments designed to obtain and manipulate objects (prehension) is one of the defining features of primates. According to the two visual system hypothesis (TVSH) vision can be parsed into two systems: (1) the ventral ‘stream’ of the occipital and inferotemporal cortex which services visual perception and other cognitive functions and (2) the ‘dorsal stream’ of the occipital and posterior parietal cortex which services skilled, goal-directed actions such as prehension. A cornerstone of the TVSH is the ‘perception-action’ dissociation observed in patient DF who suffers from visual form agnosia following bilateral damage to her ventral stream. DF …

The Effects Of Arginine Vasopressin On Maternal Behavior And Aggression In Peromyscus Californicus Mothers, Nathaniel Ng

Honors Projects

Research studies since the 1950s have shown that a chemical within the brain called arginine vasopressin (AVP) is associated with the modulation of many different social behaviors in mammals. Some of these behaviors are related to parenting, such as parental care initiation, aggression, social recognition, depression and anxiety. Understanding the physiology behind AVP regulation could allow for the creation of new therapies for treating human social disorders, such as using an AVP receptor antagonist to attenuate anxiety. This project examines how neural injections of AVP and an AVP receptor antagonist affect both maternal care and aggression in female Peromyscus californicus …

Evolutionary Convergence Of The Caffeine Biosynthetic Pathway In Chocolate Followed Duplication Of A Constrained Ancestral Enzyme, Andrew J. O'Donnell

Masters Theses

Caffeine biosynthesis is widely distributed in flowering plants and requires three consecutive methylation steps of xanthine alkaloids. Genes that have previously been reported to participate in the multi-step pathway in Coffea sp. (coffee) and Camellia sinensis (tea) encode members of the SABATH family of methyltransferases. Two genes highly expressed in fruits of Theobroma cacao (cacao) are orthologous to the caffeine genes in tea and appear to have diversified following gene duplication. Biochemical characterization of the enzymes (XMTs) encoded by these genes strongly suggest an unprecedented major pathway to theobromine, a precursor to caffeine. These findings imply that caffeine biosynthesis evolved …

Regulation Of Glial Cell Line-Derived Neurotrophic Factor (Gdnf) Production In Voluntary And Involuntary Muscle, John-Mary Vianney

Dissertations

Glia cell line-derived neurotrophic factor (GDNF) is a survival factor for subpopulations of neurons, including somatic and autonomic motor neurons. These neurons depend, in part, on GDNF that is synthesized and secreted by their target tissues. It has been shown that a number of tissues in the periphery express GDNF and these target tissues differ in their composition, function, and in the case of different muscle cell types, their contractile characteristics. Whether the processes regulating GDNF production in these different tissues is similar or different is poorly understood. The broad goal of this study is to examine factors that normally …

Mindfulness-Based Stress Reduction: Impact On The Acoustic Startle Response, Daniel Grossman

Honors Theses

Previous research has demonstrated that the magnitude and duration of the acoustic startle response can be modulated by a number of psychological factors. Mindfulness meditation, being a form of mental training known to produce benefits in affect and attention regulation as well as other domains, may modulate factors of the acoustic startle response. The present study investigated participants’ skin conductance responses to an acoustic startle stimulus before and after an 8-week Mindfulness-Based Stress Reduction (MBSR) course, and paired this assessment with self-reported trait mindfulness and positive and negative affect. There was significant startle habituation across the intervention, but no between …

Are There Multiple Kinds Of Episodic Memory? An Fmri Investigation Comparing Autobiographical And Recognition Memory Tasks, Hung-Yu Chen

Arts & Sciences Electronic Theses and Dissertations

What brain regions underlie retrieval from episodic memory? The bulk of research addressing this question has relied upon laboratory-based recognition memory. Another, less dominant tradition has employed autobiographical methods, whereby people recall events from their lifetime, often after being cued with words or pictures. Previous research comparing regions underlying successful memory retrieval between these two methodological approaches has shown mixed results. To examine the neural processes underlying recognition memory for materials encountered in the laboratory and autobiographical memory, we conducted a within-subject study using fMRI. We showed participants indoor and outdoor scenes under two types of instructions: In the lab-based …