The uncertain conductivity value of skull and brain tissue influences the accuracy of the electroencephalogram (EEG) inverse problem solution. Indeed, when the assumed conductivity in the numerical ...procedure is different from the actual conductivity then a source localization error is introduced. When using traditional least-squares minimization methods, the number of electrodes in the EEG cap does not influence the spatial resolution. A recently developed reduced conductivity dependence (RCD) methodology, based on the selection of electrodes, is able to increase the spatial resolution of the EEG inverse problem. This paper presents the implications of the RCD method when using a large number of electrodes in the EEG cap on the spatial resolution of the EEG inverse solutions. We show by means of numerical experiments that in contrast to traditional methods, the RCD method enables to increase the spatial resolution. The computations show that the EEG hardware should be modified with as large as possible electrodes.
The EEG is a neurological diagnostic tool with high temporal resolution. However, when solving the EEG inverse problem, its localization accuracy is limited because of noise in measurements and ...available uncertainties of the conductivity value in the forward model evaluations. This paper proposes the reduced conductivity dependence (RCD) method for decreasing the localization error in EEG source analysis by limiting the propagation of the uncertain conductivity values to the solutions of the inverse problem. We redefine the traditional EEG cost function, and in contrast to previous approaches, we introduce a selection procedure of the EEG potentials. The selected potentials are, as low as possible, affected by the uncertainties of the conductivity when solving the inverse problem. We validate the methodology on the widely used three-shell spherical head model with a single electrical dipole and multiple dipoles as source model. The proposed RCD method enhances the source localization accuracy with a factor ranging between 2 and 4, dependent on the dipole location and the noise in measurements.
The uncertain conductivity value of brain tissue influences the accuracy of the EEG inverse problem solution. When using traditional least-squares minimization methods, the number of electrodes that ...is used as input in the EEG inverse problem has not an influence on the resolution. However, when including a selection procedure on a high number of electrodes, the localization error is decreased. The implemented procedure selects electrodes where their potential values are not greatly influenced by the uncertain conductivity value due to their physical location relatively to the source location. This paper shows that when using a high number of electrodes, the accuracy of the EEG inverse problem is increased.
Protein restriction in early life is associated with changes in insulin sensitivity and pancreatic β-cell function during pregnancy Ignácio-Souza, LetÃcia Martins; SÃlvia Regina ReisauthorLaboratório de Avaliação Biológica de Alimentos, Faculdade de Nutrição, Universidade Federal de Mato Grosso, Avenida Fernando Correa da Costa, 2367, Boa Esperança, 78060-900, Cuiaba, MT, Brazil; Vanessa Cristina ArantesauthorDepartamento de Alimentos e Nutrição, Faculdade de Nutrição, Universidade Federal de Mato Grosso, Avenida Fernando Correa da Costa, 2367, Boa Esperança, 78060-900, Cuiaba, MT, Brazil ...
2015
Journal Article
