Alzheimer's disease (AD) is an irreversible neurodegenerative brain disease distinguished by progressive impairment of memory and decline in cognitive abilities. The hippocampus is widely recognized to play essential roles in forming and gradually transferring information from short-term memory into long-term memory, and it is involved in the onset of the neuropathological pathways of the brain to suffer neuron loss in the rise of AD. Thus, hippocampal information obtained from magnetic resonance imaging (MRI) scans have been established as crucial AD biomarkers. The hippocampus is composed of multiple subfields, and the neuron loss is not uniformly distributed on the whole hippocampus. However, this critical subfield information is not addressed by the existing surface-based morphometry (SBM) and voxel-based morphometry (VBM) studies. Due to the size, complexity, heterogeneity, and folding anatomy of the hippocampus, acquiring volumetric and morphometric measures of hippocampal subfields usually presents not only technical challenges in quantitative neuroimaging but also analytical challenges. To address these challenges and deeply understand the relationships between hippocampal shape changes and brain disorders, especially to examine the degeneration of hippocampal subfields, this thesis focuses on constructing a hippocampal subfield morphometric analysis framework including the following aspects: 1) hippocampal subfield segmentation; 2) 3D shape modeling; 3) feature formulation; 4) diffeomorphic surface registration; 5) surface shape reconstruction; and 6) association analytics. The goals include developing accurate hippocampal subfield guided registration methods, extracting useful features and identifying significant subfields on the hippocampus that are highly related to cognitive disabilities, and using such information to assist early detection of AD.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2016-05-18T16:45:01Z No. of bitstreams: 1 Paulo Tomasi Sarti_.pdf: 4227574 bytes, checksum: 4e92a5663649351d5cb26a94afe7ea81 (MD5) / Made available in DSpace on 2016-05-18T16:45:01Z (GMT). No. of bitstreams: 1 Paulo Tomasi Sarti_.pdf: 4227574 bytes, checksum: 4e92a5663649351d5cb26a94afe7ea81 (MD5) Previous issue date: 2016-02-26 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / FAPERGS - Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul / Os roedores Juliomys possuem tamanho diminuto e hábito arborícola. Desde seu estabelecimento no ano 2000, o gênero vem sendo estudado e novas informações tem sido apresentadas. Entretanto, devido ao pequeno intervalo de tempo desde então, muitas perguntas ainda esperam por respostas acerca da biologia geral, relações ecológicas, distribuição geográfica, riqueza de espécies e posição filogenética dentro dos Sigmodontinae. Especificamente, estudos morfométricos e genéticos são ferramentas importantes a serem exploradas. O objetivo geral deste estudo foi analisar a morfologia bem como os marcadores genéticos, a fim de subsidiar dados relevantes para a sistemática e biogeografia das espécies de Juliomys. Utilizamos métodos de análise morfológica, morfométrica e molecular para a definição do novo táxon, que conta com alto suporte. Produzimos mapas de potencial ocorrência das espécies de acordo com o as preferências ambientais. Testamos também o monofiletismo do gênero dentro de Sigmodontinae através do estudo de um marcador molecular. Assim, corroborando os estudos anteriores, descrevemos e propomos uma nova espécie para o gênero. Já a modelagem de distribuição das espécies revelou padrões interessantes, com distribuições desiguais ao longo do bioma Mata Atlântica. Evidenciamos ainda que Juliomys trata-se de um clado monofilético, apesar das diferenças morfológicas; dados fundamentais no embasamento de abordagens de distribuição. Ressaltamos que coleções de história natural ou coleções de Museu são fontes essenciais de informações da fauna, pois foram imprescindíveis neste estudo. A conservação da fauna toma os pressupostos da sistemática e biogeografia, como os aqui apresentados, para alicerçar suas ações. / The Juliomys are small-sized arboreal rodents. Since its establishment in 2000, the genus has been studied, and new information has been presented progressively. However, due to the short time period, many questions are still awaiting for answers related about general biology, ecological relationships, geographic distribution, species richness, and phylogenetic position within the Sigmodontinae. Morphometric and genetic studies are important tools to explore these lines. The aim of this study was to analyze the morphology and the genetic markers in order to subsidize the systematic and biogeography of Juliomys species. We use methods of morphologic, morphometric, and molecular analyses to define the new taxon. We produce maps of potential occurrence of the species according to the environmental preferences. Finally, we tested the monophyly of the genus within Sigmodontinae through the study of a molecular marker. Corroborating previous studies, we describe and propose a new species for the genus. The species distribution modeling revealed interesting patterns with unequal distributions along the Atlantic Forest biome. We endorse that Juliomys it is a monophyletic clade, despite the morphological differences. Studies grounded phylogenetically as well as monophyletic clades should be based delivery approaches. It is notorious that natural history museum collections are essential sources of wildlife information, which was crucial to this study. The conservation of fauna takes the systematic and biogeography assumptions, as those presented in this study, to underpin their actions.