Influence of head models on neuromagnetic fields and inverse source localizations

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Influence of head models on neuromagnetic fields and inverse source localizations

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dc.contributor.author Ramon, Ceon en_US
dc.contributor.author Haueisen, Jens en_US
dc.contributor.author Schimpf, Paul H. en_US
dc.date.accessioned 2010-05-06T20:04:36Z
dc.date.available 2010-05-06T20:04:36Z
dc.date.issued 2006 en_US
dc.identifier.citation Ramon C, Haueisen J, Schimpf P. Influence of head models on neuromagnetic fields and inverse source localizations. BioMedical Engineering OnLine. 2006;5(1):55. en_US
dc.identifier.other 10.1186/1475-925X-5-55 en_US
dc.identifier.uri http://www.biomedical-engineering-online.com/content/5/1/55 en_US
dc.identifier.uri http://hdl.handle.net/1773/15831
dc.description.abstract Background: The magnetoencephalograms (MEGs) are mainly due to the source currents. However, there is a significant contribution to MEGs from the volume currents. The structure of the anatomical surfaces, e.g., gray and white matter, could severely influence the flow of volume currents in a head model. This, in turn, will also influence the MEGs and the inverse source localizations. This was examined in detail with three different human head models. Methods: Three finite element head models constructed from segmented MR images of an adult male subject were used for this study. These models were: (1) Model 1: full model with eleven tissues that included detailed structure of the scalp, hard and soft skull bone, CSF, gray and white matter and other prominent tissues, (2) the Model 2 was derived from the Model 1 in which the conductivity of gray matter was set equal to the white matter, i.e., a ten tissuetype model, (3) the Model 3 consisted of scalp, hard skull bone, CSF, gray and white matter, i.e., a five tissue-type model. The lead fields and MEGs due to dipolar sources in the motor cortex were computed for all three models. The dipolar sources were oriented normal to the cortical surface and had a dipole moment of 100 [micro]A meter. The inverse source localizations were performed with an exhaustive search pattern in the motor cortex area. A set of 100 trial inverse runs was made covering the 3 cm cube motor cortex area in a random fashion. The Model 1 was used as a reference model. Results: The reference model (Model 1), as expected, performed best in localizing the sources in the motor cortex area. The Model 3 performed the worst. The mean source localization errors (MLEs) of the Model 3 were larger than the Model 1 or 2. The contour plots of the magnetic fields on top of the head were also different for all three models. The magnetic fields due to source currents were larger in magnitude as compared to the magnetic fields of volume currents. Discussion: These results indicate that the complexity of head models strongly influences the MEGs and the inverse source localizations. A more complex head model performs better in inverse source localizations as compared to a model with lesser tissue surfaces. en_US
dc.description.sponsorship This work was supported in part by the National Science Foundation under Grant No. 0112742. en_US
dc.language.iso en_US en_US
dc.title Influence of head models on neuromagnetic fields and inverse source localizations en_US
dc.type Article en_US


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