Matching Items (3)
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- All Subjects: Brain
- Creators: Bimonte-Nelson, Heather A.
Description
The objective of this small animal pre-clinical research project was to study quantitatively the long-term micro- and macro- structural brain changes employing multiparametric MRI (Magnetic Resonance Imaging) techniques. Two separate projects make up the basis of this thesis. The first part focuses on obtaining prognostic information at early stages in the case of Traumatic Brain Injury (TBI) in rat animal model using imaging data acquired at 24-hours and 7-days post injury. The obtained parametric T2 and diffusion values from DTI (Diffusion Tensor Imaging) showed significant deviations in the signal intensities from the control and were potentially useful as an early indicator of the severity of post-traumatic injury damage. DTI was especially critical in distinguishing between the cytotoxic and vasogenic edema and in identification of injury regions resolving to normal control values by day-7. These results indicate the potential of quantitative MRI as a clinical marker in predicting prognosis following TBI. The second part of this thesis focuses on studying the effect of novel therapeutic strategies employing dendritic cell (DC) based vaccinations in mice glioma model. The treatment cohorts included comparing a single dose of Azacytidine drug vs. mice getting three doses of drug per week. Another cohort was used as an untreated control group. The MRI results did not show any significant changes in between the two treated cohorts with no reduction in tumor volumes compared to the control group. The future studies would be focused on issues regarding the optimal dose for the application of DC vaccine. Together, the quantitative MRI plays an important role in the prognosis and diagnosis of the above mentioned pathologies, providing essential information about the anatomical location, micro-structural tissue environment, lesion volume and treatment response.
ContributorsAnnaldas, Bharat (Author) / Kodibagkar, Vikram (Thesis advisor) / Stabenfeldt, Sarah (Committee member) / Bhardwaj, Ratan (Committee member) / Arizona State University (Publisher)
Created2014
Description
Food is an essential driver of animal behavior. For social organisms, the acquisition of food guides interactions with the environment and with group-mates. Studies have focused on how social individuals find and choose food sources, and share both food and information with group-mates. However, it is often not clear how experiences throughout an individual's life influence such interactions. The core question of this thesis is how individuals’ experience contributes to within-caste behavioral variation in a social group. I investigate the effects of individual history, including physical injury and food-related experience, on individuals' social food sharing behavior, responses to food-related stimuli, and the associated neural biogenic amine signaling pathways. I use the eusocial honey bee (Apis mellifera) system, one in which individuals exhibit a high degree of plasticity in responses to environmental stimuli and there is a richness of communicatory pathways for food-related information. Foraging exposes honey bees to aversive experiences such as predation, con-specific competition, and environmental toxins. I show that foraging experience changes individuals' response thresholds to sucrose, a main component of adults’ diets, depending on whether foraging conditions are benign or aversive. Bodily injury is demonstrated to reduce individuals' appetitive responses to new, potentially food-predictive odors. Aversive conditions also impact an individual's social food sharing behavior; mouth-to-mouse trophallaxis with particular groupmates is modulated by aversive foraging conditions both for foragers who directly experienced these conditions and non-foragers who were influenced via social contact with foragers. Although the mechanisms underlying these behavioral changes have yet to be resolved, my results implicate biogenic amine signaling pathways as a potential component. Serotonin and octopamine concentrations are shown to undergo long-term change due to distinct foraging experiences. My work serves to highlight the malleability of a social individual's food-related behavior, suggesting that environmental conditions shape how individuals respond to food and share information with group-mates. This thesis contributes to a deeper understanding of inter-individual variation in animal behavior.
ContributorsFinkelstein, Abigail (Author) / Amdam, Gro V (Thesis advisor) / Conrad, Cheryl (Committee member) / Smith, Brian (Committee member) / Neisewander, Janet (Committee member) / Bimonte-Nelson, Heather A. (Committee member) / Arizona State University (Publisher)
Created2017
Description
Reproductive hormones are recognized for their diverse functions beyond reproduction itself, including a vital role in brain organization, structure, and function throughout the lifespan. From puberty to reproductive senescence, the female is characterized by inherent responsiveness to hormonal cyclicity. For most women, a natural transition to menopause occurs in midlife, wherein the endogenous hormonal milieu undergoes significant changes and marks the end of the reproductive life stage. Although most women experience natural menopause, many women will undergo gynecological surgery during their lifetime, which can lead to an abrupt surgical menopause. It is of critical importance to better understand how endogenous and exogenous reproductive hormone exposures across the lifespan influence cognitive and brain aging, as women are at a greater risk for developing a variety of diseases after menopause, including dementia. Using rodent models, this dissertation explores how the etiology of reproductive senescence, that is, whether it is transitional or surgical, influences the female phenotype to result in divergent cognitive outcomes dependent upon a variety of factors, with an emphasis on age at the time of intervention playing a key role in brain outcomes. Furthermore, the impact of exogenous hormone therapy on cognition is evaluated in the context of surgical menopause. A novel rat model of hysterectomy is also presented, with results demonstrating for the first time that the nonpregnant uterus, which is typically considered to be a quiescent organ, may play a unique, direct role in modulating cognitive outcomes. Neurobiological mechanisms associated with reproductive hormones and aging are assessed to better recognize neural correlates underlying the observed behavior changes. The overarching goal of this dissertation was to elucidate novel factors contributing to cognitive aging outcomes in females. Collectively, the data presented herein indicate that the age at the onset of reproductive senescence has significant implications for learning and memory outcomes, and that variations in gynecological surgery can have unique, long-lasting effects on the brain and cognition. Translationally, this series of experiments moves the field forward toward the goal of improving the health and quality of life for women throughout the lifespan.
ContributorsKoebele, Stephanie Victoria (Author) / Bimonte-Nelson, Heather A. (Thesis advisor) / Conrad, Cheryl D. (Committee member) / DeNardo, Dale F (Committee member) / Newbern, Jason M (Committee member) / Reiman, Eric M (Committee member) / Arizona State University (Publisher)
Created2019