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The Effects Of Chronic Simvastatin Treatment On The Expression Of Behavioral Symptoms In A Transgenic Mouse Model Of Huntington’S Disease, Ashley Whitmarsh

University of New Orleans Theses and Dissertations

Huntington’s disease (HD) is a heritable, neurodegenerative disorder characterized by motor, cognitive, and psychiatric disturbances. An unstable CAG expansion within the gene normally encoding for the Huntingtin protein is responsible. The expanded mutant form of Huntingtin and the putative protein co-factor Rhes interact and cause cell death within the striatum. We hypothesized chronic treatment with simvastatin, a cholesterol lowering drug, would disrupt the biosynthetical pathway which gives both Rhes and its target cells binding sites and render Rhes inactive. Healthy and HD mice were treated with simvastatin or a vehicle. Animals’ motor behavior was assessed with three separate tests over …

Reaching For The Light: The Prioritization Of Conspicuous Visual Stimuli For Reflexive Target-Directed Reaching, Daniel K. Wood

Electronic Thesis and Dissertation Repository

The degree to which something stands out against the background of its environment communicates important information. The phenomenon of camouflage is a testament of the degree to which visual salience and probability of survival tend to overlap. Salient stimuli often elicit fast, reflexive movements in order to catch prey or avoid a predator. The overarching goal of the work presented in this thesis is to investigate how the physical salience of visual stimuli influence the programming and execution of reaching movements. I approached this question by recording kinematics and muscle responses during reaching movements. Broadly, this thesis investigates the effect …

Contribution Of Trpm2 To Memory Loss In An Alzheimer's Mouse Model, Megan M. Chen

Electronic Thesis and Dissertation Repository

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by the progressive deterioration of memory and other intellectual abilities. Accumulation of amyloid-β (Aβ) peptide, the major contributor to the senile plaques central to AD, is thought to mediate neurotoxicity by inducing oxidative stress and calcium dysregulation. Transient Receptor Potential Melastatin type 2 (TRPM2) is a calcium permeable, non-selective cation channel activated under oxidative stress and ultimately induces cell death. The APPSWE/PSEN1ΔE9 double transgenic mouse model carries the human APPswe (Swedish mutations K594N/M595L) and PS1 mutations with a deletion in exon 9 (PS1-dE9), and is one of the most commonly used AD …

Neural Correlates Of Audiovisual Speech Perception In Aphasia And Healthy Aging, Sarah H. Baum

Dissertations & Theses (Open Access)

Understanding speech in face-to-face conversation utilizes the integration of multiple pieces of information, most importantly the auditory vocal sounds and visual lip movements. Prior studies of the neural underpinnings of audiovisual integration in the brain have provided converging evidence to suggest that neurons within the left superior temporal sulcus (STS) provide a critical neural hub for the integration of auditory and visual information in speech. While most studies of audiovisual processing focus on neural mechanisms within healthy, young adults, we currently know very little about how changes to the brain can affect audiovisual integration in speech. To examine this further, …

Mtorc1 Signaling In Memory Formation And Dysfunction, Natalia S. Rozas De O'Laughlin

Dissertations & Theses (Open Access)

The mechanistic Target of Rapamycin Complex 1 (mTORC1) pathway integrates cellular availability of growth factors, energy and amino acids to regulate protein synthesis and autophagy. The mTORC1 pathway has also been shown to be required for memory consolidation, and its dysregulation is associated with many neurological disorders. MTORC1 is negatively regulated by the tuberous sclerosis complex (TSC1/2). When ATP and growth factors are available, TSC1/2 is inhibited and mTORC1 activity can be restored. In a complementary regulatory pathway, amino acids signal to mTORC1 through the Rag GTPases and Ragulator complex, which modulate the translocation of mTORC1 from the cytoplasm to …

Functional Analysis Of Corazonin And Its Receptor In Drosophila Melanogaster, Kai Sha

Doctoral Dissertations

Corazonin (Crz) is an amidated undecapeptide originally isolated from the American cockroach. It has been shown to affect diverse physiological functions in a species-specific manner. However, the functionality of Crz in Drosophila melanogaster has not yet been determined. To gain insight into the role of Crz signaling in vivo, Crz and CrzR null alleles were obtained by transposable element mobilization. Flies carrying a deficiency uncovering Crz and pr-set7 loci were generated via P-element excision, and the latter was rescued by wild-type pr-set7 transgene. A mutation of Crz receptor (CrzR) was generated by Minos-element mobilization from …

Network Dynamics Of Visual Naming, Christopher R. Conner

Dissertations & Theses (Open Access)

Recognition and naming of objects and actions are fundamental components of language. They involve several different systems working in coordination to accomplish a complex behavior. During visual naming, sensory and semantic processing are carried out by dedicated cortical substrates in the temporal and occipital lobes, while response selection and articulatory planning are handled by prefrontal cortex. Despite decades of research using lesion analysis, functional MRI and electro-encephalography, the precise dynamics involved remain unknown due to the inadequate spatio-temporal resolution of these methodologies. Of particular interest is the organization of semantic knowledge and the degree of serial and parallel organization of …

Dopamine Modulation Of Emotional Learning In The Medial Prefrontal Cortex, Nicole M. Lauzon

Electronic Thesis and Dissertation Repository

Dopamine (DA) transmission plays a critical role in the processing of emotionally salient information and in associative learning and memory processes. Within the mammalian brain, neurons within the medial prefrontal cortex (mPFC) are involved critically in the encoding, expression, and extinction of emotionally salient learned information. Within the mPFC, DAergic transmission is involved importantly in controlling attention related and motivational processes, particularly within the context of emotionally salient sensory information. Considerable evidence suggests differential roles for DA D₁-like versus D₂-like receptors, including the D₄-receptor subtype, in the regulation of neuronal activity and emotional processing …

Behavioral Responses To Methylphenidate: Correlations With Neuronal Activity In The Caudate Nucleus, Catherine M. Claussen

Dissertations & Theses (Open Access)

Methylphenidate is currently a drug of abuse and readily prescribed to both adolescents and adults. Chronic methylphenidate (MPH) exposure results in an increase in DA in the motive circuit, including the caudate nucleus (CN), similar to other drugs of abuse. This study focuses on research aimed to elucidate if there are intrinsic underlying differences in the CN electrophysiological activity of animals exhibiting different chronic responses to the same dose of MPH. Behavioral and caudate nucleus (CN) neuronal activity following acute and chronic doses of MPH was assessed by simultaneously recording the behavioral and neuronal activity. The experimental protocol lasted for …

Characterization Of The Apoptotic Functions Of The Hid Hmolog Isolated From Megaselia Scalaris, Shannon Smith

Chancellor’s Honors Program Projects

No abstract provided.

The Possible Role Of Extra-Ocular Photoreceptors In The Entrainment Of Lobster Circadian Rhythms To Light:Dark Cycles, Sara A. Mckinney

Honors Theses and Capstones

The American lobster, Homarus americanus, is a decapod crustacean whose daily nocturnal rhythms of activity are driven, in part, by an internal biological clock. While this circadian clock is capable of producing a rhythm of approximately 24 hours on its own, it can also be entrained to light:dark cycles. Recent findings in our laboratory suggest that lobsters have photosensitive neurons throughout their nervous system (extra-ocular photoreceptors). The objective of this research was to test the hypothesis that these extra-ocular photoreceptors aid in entraining their daily rhythm of activity. First, the locomotion of juvenile American lobsters was measured in trials under …

Norepinephrine Involvement In The Intermittent Swim Stress-Induced Deficit In Spatial Learning And Memory, Emily Elgert

Honors Theses and Capstones

Learning and memory impairments are often caused by stress disorders including depression. The present study investigated the involvement of norepinephrine in the swim stress-induced deficits of spatial learning and memory. Exposure to intermittent swim stress (ISS) followed by learning and memory tests in the Morris water maze (MWM) were used to investigate this relationship. The ISS paradigm consists of intermittent exposure to cold water, producing stress responses in rats. Reboxetine, a norepinephrine selective reuptake inhibitor (NSRI), was employed to investigate whether this compound reverses the ISS-induced deficit. In other words, rats exposed to the ISS, were hypothesized to experience impaired …

Determination Of Catecholamine Content Changes In Mouse Brain Following Chronic Ketogenic Diet, Ryan Adams

Senior Theses and Projects

This work investigated the effects of the ketogenic diet on catecholamine concentrations in the brains of mice. The ketogenic diet has been show to modulate the catecholamine concentrations in the cerebrospinal fluid of children as well as altering hippocampal norepinephrine levels in mice. Tissue homogenates of the motor cortex, somatosensory cortex, nucleus accumbens, anterior caudate, posterior caudate and midbrain regions were analyzed using high pressure liquid chromatography to quantitate norepinephrine, dopamine, 3, 4-dihydroxyphenylacetic acid (DOPAC), 5-hydroxyindoleacetic acid (5HIAA), homovanillic acid (HVA) and serotonin (5-HT). No significant differences in catecholamine concentration levels were detected in the tissue homogenates. Analysis of metabolite …

Exploring The Neural Basis Of Top-Down Guided Action In Macaque Monkeys, Jessica M. Phillips

Electronic Thesis and Dissertation Repository

To thoroughly characterize any brain mechanism requires an appropriate animal model for invasive studies. An invaluable model system used toward a comprehension of cognitive neurophysiology is the macaque monkey. It is important to delineate similarities and limitations for this model in relation to the human brain and cognition. In this thesis, we have thus conducted three experiments to investigate putative generalizations between monkeys and humans regarding the neural processes associated with top-down action control in monkeys.

Our daily behaviour is largely comprised of automatic routine actions. The frequent repetition of certain behaviours in response to particular contexts can give rise …

Circadian Rhythms In Reward And Underlying Neural Circuits, Ricardo M. Baltazar

Electronic Thesis and Dissertation Repository

Studies suggest that the circadian timing system exerts an important influence on responses to rewarding stimuli. Diurnal rhythms in the rewarding value of amphetamine and mating behavior were observed, but differed in the pattern of their timing. Daily fluctuations in reward were correlated with oscillations in mesolimbic dopaminergic activity in both the nucleus accumbens (NAc) and ventral tegmental area (VTA), with a peak in NAc coinciding with the peak of sex reward, while the peak in the VTA associated with the peak in amphetamine reward. Also, rhythmic expression of the marker of neural activation, cFos, was observed in NAc, medial …

Influences Of Ecological Light Pollution On Advertisement Calls Of Spea Multiplicata (Amphibia: Anura: Scaphiopodidae) In Rural And Urban Populations In The Northern Chihuahuan Desert And An Evaluation Of Hybrid S. Bombifrons X S. Multiplicata Calls, Katie Anderson

Open Access Theses & Dissertations

Spea is a genus of toad-like, arid adapted frogs distributed throughout much of the western U.S. and northern Mexico. Two species, (S. Bombifrons and S. Multiplicata) are syntopic throughout most of the northern Chihuahuan Desert, a region that is experiencing rapid urbanization. For this study, I examined 936 male advertisement calls from urban and rural populations of S. multiplicata, and a rural population of S. bombifrons in west Texas and south-central New Mexico. Advertisement calls from urban and rural S. multiplicata were compared against light level to assess the potential influence ecological light pollution plays in sexual …

Injury Establishes Constitutive Μ-Opioid Receptor Activity Leading To Lasting Endogenous Analgesia And Dependence, Gregory F. Corder

Theses and Dissertations--Physiology

Injury causes increased pain sensation in humans and animals but the mechanisms underlying the emergence of persistent pathological pain states, which arise in the absence of on-going physical damage, are unclear. Therefore, elucidating the physiological regulation of such intractable pain is of exceptional biomedical importance. It is well known that endogenous activation of µ-opioid receptors (MORs) provides relief from acute pain but the consequences of prolonged endogenous opioidergic signaling have not been considered. Here we test the hypothesis that the intrinsic mechanisms of MOR signaling promote pathological sensitization of pain circuits in the spinal cord. We found that tissue inflammation …

The Effect Of Visual Wulst Lesions And Trigeminal Nerve Sectioning On The Discrimination Of Magnetic Inclination In The Homing Pigeon (Columba Livia), Merissa Acerbi

Honors Projects

The ability of homing pigeons to return to their loft from unknown places has fascinated scientists for centuries. It is well established that homing pigeons, like migratory birds, posses an innate magnetic inclination compass to determine direction by measuring the angle between the magnetic field vector and the Earth's surface. Recent work has indicated that the avian magnetic compass is light mediated and appears to mediate magnetic information to the brain. This occurs via a visual pathway with processing in the visual Wulst area of the forebrain. There is, however, also evidence from other avian species that magnetic direction may …

Diet-Induced Obesity: Dopaminergic And Behavioral Mechanisms As Outcomes And Predictors, Vidya Narayanaswami

Theses and Dissertations--Pharmacy

Obesity and drug abuse share common neural circuitries including the mesocoticolimbic and striatal dopamine reward system. In the current study, a rat model of diet-induced obesity (DIO) was used to determine striatal dopamine function, impulsivity and motivation as neurobehavioral outcomes and predictors of obesity. For the outcome study, rats were randomly assigned a high-fat (HF) or a low-fat (LF) diet for 8 wk. Following the 8-wk HF-diet exposure, rats were segregated into obesity-prone and obesity-resistant groups based on maximum and minimum body weight gain, respectively, and neurobehavioral outcomes were evaluated. For the predictor study, neurobehavioral antecedents were evaluated prior to …

Cognitive And Physiological Moderators Of Daily Smokers' Early Neural Attentional Biases To Smoking And Nonsmoking Cues, Patrick John Hammett

Dissertations, Theses, and Masters Projects

No abstract provided.

Effects Of Intranasally Administered Dnsp-11 On The Central Dopamine System Of Normal And Parkinsonian Fischer 344 Rats, James H. Sonne

Theses and Dissertations--Neuroscience

Due to the blood-brain barrier, delivery of many drugs to the brain has required intracranial surgery which is prone to complication. Here we show that Dopamine Neuron Stimulating Peptide 11 (DNSP-11), following non-invasive intranasal administration, protects dopaminergic neurons from a lesion model of Parkinson’s disease in the rat. A significant and dose-dependent increase in an index of dopamine turnover (the ratio of DOPAC to dopamine) was observed in the striatum of normal young adult Fischer 344 rats by whole-tissue neurochemistry compared to vehicle administered controls.

Among animals challenged with a moderate, unilateral 6-hydroxy-dopamine (6-OHDA) lesion of the substantia nigra, those …

Post-Traumatic Sleep Following Diffuse Traumatic Brain Injury, Rachel K. Rowe

Theses and Dissertations--Neuroscience

Traumatic brain injury (TBI) is a major cause of death and disability throughout the world with few pharmacological treatments available for individuals who suffer from neurological morbidities associated with TBI. Cellular and molecular pathological processes initiated at the time of injury develop into neurological impairments, with chronic sleep disorders (insomnia, hypersomnolence) being among the somatic, cognitive and emotional neurological impairments. Immediately post-injury, TBI patients report excessive daytime sleepiness, however, discordant opinions suggest that individuals should not be allowed to sleep or should be frequently awoken following brain injury. To provide adequate medical care, it is imperative to understand the role …