Influence of skull anisotropy for the forward and inverse problem in EEG: simulation studies using FEM on realistic head models.
Hum Brain Mapp
; 6(4): 250-69, 1998.
Article
em En
| MEDLINE
| ID: mdl-9704264
ABSTRACT
For the sake of realism in the description of conduction from primary neural currents to scalp potentials, we investigated the influence of skull anisotropy on the forward and inverse problems in brain functional imaging with EEG. At present, all methods available for cortical imaging assume a spherical geometry, or when using realistic head shapes do not consider the anisotropy of head tissues. However, to our knowledge, no study relates the implication of this simplifying hypothesis on the spatial resolution of EEG for source imaging. In this paper, a method using finite elements in a realistic head geometry is implemented and validated. The influence of erroneous conductivity values for the head tissues is presented, and results show that the conductivities of the brain and the skull in the radial orientation are the most critical ones. In the inverse problem, this influence has been evaluated with simulations using a distributed source model with a comparison of two regularization techniques, with the isotropic model working on data sets produced by a nonisotropic model. Regularization with minimum norm priors produces source images with spurious activity, meaning that the errors in the head model totally annihilate any localization ability. But nonlinear regularization allows the accurate recovery of simultaneous spots of activity, while the restoration of very close active regions is profoundly disabled by errors in the head model. We conclude that for robust cortical source imaging with EEG, a realistic head model taking anisotropy of tissues into account should be used.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Crânio
/
Encéfalo
/
Mapeamento Encefálico
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Eletroencefalografia
/
Cabeça
Tipo de estudo:
Prognostic_studies
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Risk_factors_studies
Limite:
Humans
Idioma:
En
Revista:
Hum Brain Mapp
Assunto da revista:
CEREBRO
Ano de publicação:
1998
Tipo de documento:
Article
País de afiliação:
França