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Master's Dissertation
DOI
10.11606/D.95.2011.tde-03072012-172159
Document
Author
Full name
Gilson Vieira
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2011
Supervisor
Committee
Baccala, Luiz Antonio (President)
Baldo, Marcus Vinicius Chrysostomo
Hashimoto, Ronaldo Fumio
Title in Portuguese
Modelagem matemática-computacional da conectividade cerebral em ressonância magnética funcional para o estudo do estado de repouso
Keywords in Portuguese
Conectividade Funcional
Estado de Repouso
Grafos
Ressonância Magnética Funcional
Abstract in Portuguese
Esta dissertação desenvolve e aplica métodos para caracterizar regiões cerebrais durante o estado de repouso. Utilizam-se grafos para representar a inter-dependência temporal de sinais de ressonância magnética funcional provenientes de regiões cerebrais distintas. Vértices representam regiões cerebrais e arestas representam a conectividade funcional. Buscando superar os problemas de visualização e interpretação desta forma de representação, elaboram-se métodos quantitativos para caracterizar padrões de conectividade entre regiões cerebrais. Para cada sujeito analisado: 1) Faz-se a redução da dimensionalidade espacial das imagens de ressonância magnética funcional respeitando os limites anatômicos das regiões cerebrais. 2) Estima-se a rede de conectividade funcional pela coerência direcionada entre pares de regiões distintas. 3) Constrói-se um grafo direcionado e pesado pela medida de conectividade. 4) Quantificam-se os vértices por índices e faz-se o registro destes valores no espaço comum MNI. 5) Avalia-se a consistência de cada índice pelo teste não paramétrico de Friedman seguido de análises de múltiplas comparações. A análise de 198 imagens de sujeitos sadios produziu resultados consistentes e biologicamente plausíveis. Em sua maioria, revelou regiões associadas a conceitos anatômicos de conectividade e integração cerebral. Embora de implementação simples, o método proporciona informações de natureza dinâmica sobre as relações entre diferentes regiões cerebrais e pode ser utilizado futuramente para estudar e entender desordens psiquiátricas/neurológicas.
Title in English
fMRI Resting-state Graph Index Analysis in Classical Neural Systems
Keywords in English
Brain Connectivity
Functional Magnetic Resonance Image
Graphs
Resting State.
Abstract in English
This dissertation develops and applies methods to characterize brain regions during resting state. Graphs are used to represent functional MRI connectivity from different brain regions. Vertices represent brain regions and edges represent connectivity. To overcome the visualization and interpretation problems of this form of representation, we developed quantitative methods to characterize its patterns. Methods: For each subject: 1) The reduction of spatial dimensionality of functional magnetic resonance imaging is carried out taking into account the anatomic limits of the brain regions. 2) The network is estimated by directed coherence between pairs of separate regions. 3) A directed graph with weights on its edges is constructed using the later connectivity measure. 4) The vertices are quantified by indexes that are registered in the MNI common space. 5) The consistency of each index is evaluated by the nonparametric Friedman followed by Post-Hoc analysis. Results: The analysis of 198 images of healthy subjects produced consistent and biologically plausible results. They revealed anatomical regions involved in brain integration. Conclusion: The method provides information about the dynamic nature of the relationships between different brain regions and can be used in future clinical studies to understand psychiatric and neurological disorders.
 
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dissertacao.pdf (3.50 Mbytes)
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Publishing Date
2012-07-11
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • ARCURI, S. M., et al. Functional Disconnectivity and Thought Disorder in Schizophrenia: I Integrating clinical, neuropsychological, neuroimaging and functional connectivity data. In The 15th Biennial Winter Workshop in Psychoses, Barcelona, 2009. The 15th Biennial Winter Workshop in Psychoses., 2009. Abstract.
  • Arcuri, Silvia M., et al. FUNCTIONAL DISCONNECTIVITY AND FORMAL THOUGHT DISORDER IN SCHIZOPHRENIA: INTEGRATING CLINICAL, NEUROPSYCHOLOGICAL, NEUROIMAGING AND FUNCTIONAL CONNECTIVTY DATA [doi:10.1016/j.schres.2010.02.345]. In 2nd Biennial Schizophrenia INternational Research Conference, Florence, 2010. Schizophrenia Research., 2010. Resumo.
  • Arcuri, Silvia M., et al. Functional Disconnectivity and Thought Disorder in Schizophrenia: II Specific brain actiavation differences between patients with and without Formal Thought Disorde. In The 15th Biennial Winter Workshop in Psychoses, Barcelona, 2009. The 15th Biennial Winter Workshop in Psychoses., 2009. Abstract.
  • Vieira, G., et al. Finding fMRI Resting-state Network (RSN) Structures with Help of Graph Hubs And Authorities. In Organization for Brain Mapping OHBM2012, Beijing, 2012. OHBM2012., 2012. Abstract. Available from: http://https://ww4.aievolution.com/hbm1201/index.cfm?do=abs.viewAbs&abs=5018.
  • Vieira, Gilson, et al. Finding fMRI Resting-state Network (RSN) Structures with Help of Graph Hubs And Authorities. In Organization for Human Brain Mapping, Beijing, 2012. OHBM2012., 2012. Abstract.
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