The impact of normalization and segmentation on resting state brain networks

• Autor(a) principal: Magalhães, Ricardo José Silva
• Data de Publicação: 2015
• Outros Autores: Marques, Paulo César Gonçalves, Soares, José Miguel, Alves, Vitor, Sousa, Nuno
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/1822/33578
• topic: Neuroimaging; FMRI; Graph-Theory; Pre-Processing; Brain parcellation; Normalization; Science & Technology

Graph theory has recently received a lot of attention from the neuroscience community as a method to represent and characterize brain networks. Still, there is a lack of a gold standard for the methods that should be employed for the preprocessing of the data and the construction of the networks, as well as a lack of knowledge on how different methodologies can affect the metrics reported. We used graph theory analysis applied to resting-state functional Magnetic Resonance Imaging (rs-fMRI) to investigate the influence of different node-defining strategies and the effect of normalizing the functional acquisition on several commonly reported metrics used to characterize brain networks. The nodes of the network were defined using either the individual FreeSurfer segmentation of each subject or the FreeSurfer segmented MNI (Montreal National Institute) 152 template, using the Destrieux and sub-cortical atlas. The functional acquisition was either kept on the functional native space or normalized into MNI standard space. The comparisons were done at three levels: on the connections, on the edge properties and on the network properties levels. Our results reveal that different registration and brain parcellation strategies have a strong impact on all the levels of analysis, possibly favoring the use of individual segmentation strategies and conservative registration approaches. In conclusion, several technical aspects must be considered so that graph theoretical analysis of connectivity MRI data can provide a framework to understand brain pathologies.