Ce mémoire s'intéresse à la reconstruction d'un modèle 3D à partir de plusieurs images. Le modèle 3D est élaboré avec une représentation hiérarchique de voxels sous la forme d'un octree. Un cube englobant le modèle 3D est calculé à partir de la position des caméras. Ce cube contient les voxels et il définit la position de caméras virtuelles. Le modèle 3D est initialisé par une enveloppe convexe basée sur la couleur uniforme du fond des images. Cette enveloppe permet de creuser la périphérie du modèle 3D. Ensuite un coût pondéré est calculé pour évaluer la qualité de chaque voxel à faire partie de la surface de l'objet. Ce coût tient compte de la similarité des pixels provenant de chaque image associée à la caméra virtuelle. Finalement et pour chacune des caméras virtuelles, une surface est calculée basée sur le coût en utilisant la méthode de SGM. La méthode SGM tient compte du voisinage lors du calcul de profondeur et ce mémoire présente une variation de la méthode pour tenir compte des voxels précédemment exclus du modèle par l'étape d'initialisation ou de creusage par une autre surface. Par la suite, les surfaces calculées sont utilisées pour creuser et finaliser le modèle 3D. Ce mémoire présente une combinaison innovante d'étapes permettant de créer un modèle 3D basé sur un ensemble d'images existant ou encore sur une suite d'images capturées en série pouvant mener à la création d'un modèle 3D en temps réel. / This master concentrates on the reconstruction of a 3D model from multiple images. The 3D model is built with a hierarchical representation of voxels using an octree. A cube surrounding the object is calculated from the camera's positions. This cube contains all the voxels and it defines the position of the virtual cameras. The 3d model is initialized by a visual hull that is based on the uniform color of the images’ background. This visual hull is used to pre-carve the 3D model. Then a cost is calculated to evaluate the quality of each voxel as being on the surface of the object. This cost takes into account the similarity of the pixels from each images associated to a virtual camera. Finally a surface is calculated for each virtual camera using the SGM method that is based on the voxel cost. The SGM method takes the surrounding voxels into account when calculating the depth and this master presents a variation to this method where we take the previously excluded voxels into account. The excluded voxels coming from the initialization step or from the carving done by another virtual camera. The resulting surface is used to carve the voxel representation. This master presents an innovative combination of steps leading to the creation of a 3D model from a set of existing images or from a series of images capture one after another leading to a real-time creation of a 3D model.

Vestibular-related problems (dizziness, vertigo, and imbalance) are common sequelae following concussion and blast exposures that result in mild traumatic brain injury (mTBI). However, the anatomical substrate connected to these dysfunctions is not well understood. To provide a better understanding of this area, we used voxel-based morphometry (VBM) as a platform for studying vestibular-related mTBI in the human brain. Briefly, VBM is a group comparison study which evaluates structural differences in magnetic resonance (MR) images between agematched groups of individuals (11 vestibular TBI patients and 10 controls). Using the VBM-8 Toolbox and statistical probability mapping (SPM), MRI images were segmented into gray matter, white matter, and cerebrospinal fluid, normalized into a standardized anatomical space, and then analyzed statistically for significant anatomical differences between groups. Based on the VBM analysis, most notable differences in brain anatomy were characterized by reductions in gray matter volume observed in the middle frontal gyrus, mesial frontal lobe, and in the insular area in the left mesial temporal lobe. These findings provide a preliminary analysis of distributed gray matter changes in key frontal and temporal areas of the brain associated with mTBI related vestibular dysfunction.

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Agradecemos a compreensão. on 2016-04-27T16:55:50Z (GMT) / Submitted by ALINE MARQUES DA SILVA BRAGA null (aline.sms@gmail.com) on 2016-05-16T12:39:41Z No. of bitstreams: 1 Tese Aline.pdf: 9957836 bytes, checksum: 6bc924ddc7c437583c8bda4fb0a99ab3 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-05-16T14:36:42Z (GMT) No. of bitstreams: 1 braga_ams_dr_bot.pdf: 9957836 bytes, checksum: 6bc924ddc7c437583c8bda4fb0a99ab3 (MD5) / Made available in DSpace on 2016-05-16T14:36:42Z (GMT). No. of bitstreams: 1 braga_ams_dr_bot.pdf: 9957836 bytes, checksum: 6bc924ddc7c437583c8bda4fb0a99ab3 (MD5) Previous issue date: 2016-02-18 / Fundação de Amparo à Pesquisa do Estado de Mato Grosso (FAPEMAT) / Fundamento: Evidências experimentais de modelos animais de crises de ausência sugerem focalidades no início das descargas generalizadas. Estudos clínicos indicam que pacientes com o diagnóstico de epilepsia generalizada idiopática (EGI) exibem anormalidades focais que envolvem o circuito tálamo-cortical no eletroencefalograma (EEG) e na neuroimagem. Objetivos: Investigar a presença de características focais nas descargas generalizadas interictais usando análise quantitativa do EEG (EEGq) e avaliar o córtex do giro do cíngulo usando múltiplas abordagens quantitativas de neuroimagem. Métodos: 75 EEGs de 64 pacientes foram analisados. A primeira espícula generalizada inequívoca foi marcada para cada descarga. Três métodos de análise de fonte geradora da atividade observada foram aplicados: transformação do dipolo em imagem (dipole source imaging-DSI), abordagem LORETA aplicada iterativamente (CLARA), e análise de dipolo equivalente de componentes independentes com análise de agrupamentos. Após processamento do EEG, 32 pacientes (18 mulheres, 32 ± 11) fizeram ressonância magnética. Foram utilizados três métodos para comparar o giro do cíngulo de pacientes e controles: morfometria baseada em voxel (VBM), análise cortical e análise de formato. Resultados: 753 descargas generalizadas foram analisadas. Usando as três técnicas, o lobo frontal foi a principal fonte das descargas (70%), seguido pelos lobos parietal e occipital (14%) e, por fim, os núcleos da base (12%). As principais fontes anatômicas das descargas generalizadas foram o córtex da porção anterior do giro do cíngulo (36%) e giro frontal medial (23%). A VBM mostrou atrofia de substância cinzenta na porção anterior do giro do cíngulo (972 mm3) e no istmo (168 mm3). Análises individuais do córtex do giro do cíngulo mostraram resultados semelhantes. Comparações de superfície mostraram anormalidades principalmente na porção posterior do giro do cíngulo (718.12 mm2). A análise de formato demonstrou uma predominância de anormalidades nas porções anterior e posterior do giro do cíngulo. Discussão: A análise de fonte não mostrou uma fonte única comum a todas as descargas generalizadas mas indicou predominância do giro do cíngulo e lobo frontal. Além disso, o estudo sugere a existência de anormalidades estruturais sutis no giro do cíngulo, principalmente nas porções anterior e posterior. / Background: Experimental evidence from animal models of absence seizures suggests a focal source for the initiation of generalized spike-and-wave (GSW) discharges. Clinical studies indicate that patients diagnosed with idiopathic generalized epilepsy (IGE) exhibit focal electroencephalographic and subtle structural abnormalities, which involve the thalamo-cortical circuitry. Aims: The objectives of the current investigation were to investigate whether interictal generalized discharges exhibit focal characteristics using qEEG analysis and to perform a comprehensive analysis of the cingulate cortex using multiple quantitative structural neuroimaging techniques. Methods: 75 EEG recordings from 64 patients were analyzed. The first unequivocally confirmed generalized spike was marked for each discharge. Three methods of source imaging analysis were applied: dipole source imaging (DSI), classical LORETA analysis recursively applied (CLARA), and equivalent dipole of independent components with cluster analysis. After EEG analysis, 32 patients (18 women, 30± 10 years) and 36 controls (18 women, 32 ±11 years) were imaged by 3 Tesla magnetic resonance (MRI). We used three models to compare cingulate gyrus of patients and the control group: voxel-based morphometry (VBM), cortical analyses and shape analyses. Results: A total of 753 GSW discharges were spatiotemporally analyzed. Source analysis using all three techniques revealed that the frontal lobe was the principal source of GSW discharges (70%), followed by the parietal and occipital lobes (14%), and the basal ganglia (12%). The main anatomical sources of the generalized discharges were the anterior cingulate cortex (36%) and the medial frontal gyrus (23%). VBM analyses of cingulate gyrus showed areas of gray matter atrophy, mainly in the anterior cingulate gyrus (972 mm3) and the isthmus (168 mm3). Individual analyses of the cingulate cortex were similar between patients with IGE and controls. Surface- based comparisons revealed abnormalities located mainly in the posterior cingulate cortex (718.12 mm2). Shape analyses demonstrated a predominance of abnormalities in the anterior and posterior portions of cingulate gyrus abnormalities. Discussion: Source analysis did not reveal a common focal source of generalized discharges. However, there was a predominance of GSW discharges originating from the cingulate gyrus and the frontal lobe. Furthermore, this study suggests that patients with IGE have structural abnormalities in the cingulate gyrus mainly localized at the anterior and posterior portions. This finding is subtle and variable among patients. / FAPEMAT: 11/16452-2

Orientador: Luiz Eduardo Gomes Garcia Betting / Resumo: Fundamento: Evidências experimentais de modelos animais de crises de ausência sugerem focalidades no início das descargas generalizadas. Estudos clínicos indicam que pacientes com o diagnóstico de epilepsia generalizada idiopática (EGI) exibem anormalidades focais que envolvem o circuito tálamo-cortical no eletroencefalograma (EEG) e na neuroimagem. Objetivos: Investigar a presença de características focais nas descargas generalizadas interictais usando análise quantitativa do EEG (EEGq) e avaliar o córtex do giro do cíngulo usando múltiplas abordagens quantitativas de neuroimagem. Métodos: 75 EEGs de 64 pacientes foram analisados. A primeira espícula generalizada inequívoca foi marcada para cada descarga. Três métodos de análise de fonte geradora da atividade observada foram aplicados: transformação do dipolo em imagem (dipole source imaging-DSI), abordagem LORETA aplicada iterativamente (CLARA), e análise de dipolo equivalente de componentes independentes com análise de agrupamentos. Após processamento do EEG, 32 pacientes (18 mulheres, 32 ± 11) fizeram ressonância magnética. Foram utilizados três métodos para comparar o giro do cíngulo de pacientes e controles: morfometria baseada em voxel (VBM), análise cortical e análise de formato. Resultados: 753 descargas generalizadas foram analisadas. Usando as três técnicas, o lobo frontal foi a principal fonte das descargas (70%), seguido pelos lobos parietal e occipital (14%) e, por fim, os núcleos da base (12%... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Background: Experimental evidence from animal models of absence seizures suggests a focal source for the initiation of generalized spike-and-wave (GSW) discharges. Clinical studies indicate that patients diagnosed with idiopathic generalized epilepsy (IGE) exhibit focal electroencephalographic and subtle structural abnormalities, which involve the thalamo-cortical circuitry. Aims: The objectives of the current investigation were to investigate whether interictal generalized discharges exhibit focal characteristics using qEEG analysis and to perform a comprehensive analysis of the cingulate cortex using multiple quantitative structural neuroimaging techniques. Methods: 75 EEG recordings from 64 patients were analyzed. The first unequivocally confirmed generalized spike was marked for each discharge. Three methods of source imaging analysis were applied: dipole source imaging (DSI), classical LORETA analysis recursively applied (CLARA), and equivalent dipole of independent components with cluster analysis. After EEG analysis, 32 patients (18 women, 30± 10 years) and 36 controls (18 women, 32 ±11 years) were imaged by 3 Tesla magnetic resonance (MRI). We used three models to compare cingulate gyrus of patients and the control group: voxel-based morphometry (VBM), cortical analyses and shape analyses. Results: A total of 753 GSW discharges were spatiotemporally analyzed. Source analysis using all three techniques revealed that the frontal lobe was the principal ... (Complete abstract click electronic access below) / Doutor

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is an effective symptomatic treatment for pharmacoresistant dystonic syndromes. The relationship between grey matter volume and intracortical inhibition of the primary motor cortex (MI) in regard to the effectiveness and the state (ON/OFF) of GPi DBS was analysed in the first study. The grey matter of chronically treated patients showed hypertrophy of the supplementary motor area and cerebellar vermis whereas this difference was more significant in patients with a better clinical outcome. The grey matter of the cerebellar hemispheres of the patients showed positive correlation with the improvement of an intracortical inhibition which was generally less effective in patients regardless of the GPi DBS state. Moreover, we showed the same level of SICI in the good responders as in the healthy controls, while in non-responders was the SICI decreased. In the second study, by using paired associative stimulation (PAS) we studied the influence of primary somatosensory cortex (SI) on the MI excitability in dystonia in regards to the effectiveness of GPi DBS. SI PAS decreased the MI excitability in the GPi DBS ON state while switching the stimulation off decreased an inhibitory effect of SI on MI excitability. Non-responders showed a...

Natural disasters strike anywhere, disrupting local communication and transportation infrastructure, making the process of assessing specific local damage difficult, dangerous, and slow. The goal of Building Damage Assessment (BDA) is to quickly and accurately estimate the location, cause, and severity of the damage to maximize the efficiency of rescuers and saved lives. In current machine learning BDA solutions, attention operators are the most recent innovations adopted by researchers to increase generalizability and overall performances of Convolutional Neural Networks for the BDA task. However, the latter, nowadays exploit attention operators tailored to the specific task and specific neural network architecture, leading them to be hard to apply to other scenarios. In our research, we want to contribute to the BDA literature while also addressing this limitation. We propose Global Voxel Transformer Operators (GVTOs): flexible attention-operators originally proposed for Augmented Microscopy that can replace up-sampling, down-sampling, and size-preserving convolutions within either a U-Net or a general CNN architecture without any limitation. Dissimilar to local operators, like convolutions, GVTOs can aggregate global information and have input-specific weights during inference time, improving generalizability performance, as already proved by recent literature. We applied GVTOs on a state-of-the-art BDA model and named it GVT-BDNet. We trained and evaluated our proposal neural network on the xBD dataset; the largest and most complete dataset for BDA. We compared GVT-BDNet performance with the baseline architecture (BDNet) and observed that the former improves damaged buildings segmentation by a factor of 0.11. Moreover, GVT-BDNet achieves state-of-the-art performance on a 10% split of the xBD training dataset and on the xBD test dataset with an overall F1- score of 0.80 and 0.79, respectively. To evaluate the architecture consistency, we have also tested BDNet’s and GVT-BDNet’s generalizability performance on another segmentation task: Tree & Shadow segmentation. Results showed that both models achieved overall good performances, scoring an F1-score of 0.79 and 0.785, respectively. / Naturkatastrofer sker överallt, stör lokal kommunikations- och transportinfrastruktur, vilket gör bedömningsprocessen av specifika lokala skador svår, farlig och långsam. Målet med Building Damage Assessment (BDA) är att snabbt och precist uppskatta platsen, orsaken och allvarligheten av skadorna för att maximera effektiviteten av räddare och räddade liv. Nuvarande BDA-lösningar använder Convolutional Neural Network (CNN) och ad-hoc Attention Operators för att förbättra generaliseringsprestanda. Nyligen föreslagna attention operators är dock specifikt skräddarsydda för uppgiften och kan sakna flexibilitet för andra scenarier eller neural nätverksarkitektur. I vår forskning bidrar vi till BDA -litteraturen genom att föreslå Global Voxel Transformer Operators (GVTO): flexibla attention operators som kan appliceras på en CNN -arkitektur utan att vara bundna till en viss uppgift. Nyare litteratur visar dessutom att de kan öka utvinningen av global information och därmed generaliseringsprestanda. Vi tillämpade GVTO på en toppmodern CNN-modell för BDA. GVTO: er förbättrade skadessegmenteringsprestandan med en faktor av 0,11. Dessutom förbättrade de den senaste tekniken för xBD-testdatauppsättningen och nådde toppmodern prestanda på en 10% delning av xBD-träningsdatauppsättningen. Vi har också utvärderat generaliserbarheten av det föreslagna neurala nätverket på en annan segmenteringsuppgift (Tree Shadow segmentering), vilket uppnådde över lag bra prestationer.

Background: Adolescence and young adulthood are particularly vulnerable periods for the development of mental health disorders, including bipolar disorder (BD). Mental health screening at universities could aid in the early identification of particularly at- risk individuals, with the long-term aim of providing early treatment interventions to improve clinical outcomes. However, further research into the identification of appropriate behavioral and biological markers for vulnerability to psychiatric disorders – as well as into the acceptability and efficacy of mental health screening - is warranted. Methods: Young adults were recruited via an already existing Internet-based mental health screening survey of undergraduate students at the University of Oxford. In Study 1, qualitative interviews of young adults with and without previous mental health problems were conducted to assess the acceptability and efficacy of mental health screening within a university setting. In Studies 2-5 we explored the hypotheses of altered emotional decision-making, reward processing and neurostructural integrity as behavioral and neurobiological markers for vulnerability to bipolar disorder via the study of young adults with a common bipolar phenotype (BPP) - some of whom meet diagnostic criteria for bipolar II or not-otherwise-specified disorder (BD II/NOS). To that end, we employed a diverse range of methodologies: alcohol challenge (Study 2); neuropsychological task performance (Study 3); functional magnetic resonance imaging (fMRI; Study 4); diffusion tensor imaging (DTI) and voxel-based morphometry (VBM; Study 5). Results: Findings from Study 1 suggest that young adults are willing to participate in mental health screening within a university setting, and that such screening may be used to offer subsequent treatment interventions. Taken together, findings from Studies 2 and 4 suggest a general blunted reward response among unmedicated young adults at increased risk for BD during euthymia, and additionally suggest pathophysiological similarities between BD and alcohol use disorders (AUDs) that may provide a causal link between the elevated co-occurrence rates of the two disorders. Finally, findings from Study 5 suggest widespread white matter microstructural alterations – which are likely to be neurodevelopmental in origin – among antipsychotic- and mood-stabilizer naïve young adults with BD II/NOS. Conclusions: These data support the hypothesis of neurodevelopmental alterations identifiable prior to significant clinical impairment among young adults at increased risk of – or already meeting DSM-IV criteria for – bipolar disorder. They also suggest that young adults in higher education are willing to participate in mental health screening. Future studies should aim to identify more specific markers for individual disorders such as BD.

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Attention deficit/hyperactivity disorder (ADHD) is a common disease with a worldwide prevalence of 5% on preschool children. It has been reported that ADHD patients have volume variant in partial brain regions. Futhermore, functional magnetic resonance imaging have also been used to detect function variant possibility in particular brain regions. In the last decade, some researchers used diffusion MR imaging to investigate the abnormality of neural fibers in disease involved with central nervous system. In general, the diffusion anisotropy of white matter in both ADHD patients and healthy subjects can be estimated seperately to undergo inter-subject comparison. While previous studies often used the popular ICBM brain template (MNI152), this study applied a self-made template of Taiwan adolescents as the common space of image normailization. In this work, group comparison of diffusion fractional anisotropy was performing by using two methods, TBSS and VBM. Both manners found a decreased FA in white matter of ADHD subjects compared with normal control group. However, regions detected by different methods showed low reproducibility. The areas of significant difference include inferior longitudinal fasciculus¡Binternal capsule¡Bexternal capsule¡Bsuperior longitudinal fasciculus¡Boptic radiation¡Bsuperior frontal¡Bsuperior region of corona radiata¡Bcorticospinal tract¡Bposterior region of corona radiata / superior longitudinal fasciculus¡Bsuperior fronto-occipital fasciculus¡Banterior region of corona radiata¡Bgenu of corpus callosum nerve fibers.

Attention deficit hyperactivity disorder (ADHD) is a neurobehavior developmental disorder that affects around 7.5% of Taiwan children. With the use of magnetic resonance imaging , many results have been reported that ADHD patients have volume atrophy in gray matter and dysfunction in couples of cortical regions. In recent years, diffusion MR imaging with diffusion-sensitizing gradients has been used to investigate the abnormality of neural fibers in disease involved with central nervous system. In this study, the anisotropy of white matter in both ADHD patients and age-matched healthy subjects was estimated using diffusion tensor imaging to undergo inter-subject comparison. In this work, a significant decrease (FWE-corrected p-value <0.05) of FA values has been found in white matter of adolescents diagnosed as ADHD patients, compared with normal controls group. The areas that confirmed by two different algorithms of inter-subject comparison are mainly diffused on white matter region, including middle cerebellar peduncle, left inferior longitudinal fasciculus, internal capsule, left optic radiation, external capsule, splenium of the corpus callosum, superior longitudinal fasciculus, superior frontal and parietal-occipital nerve fibers.