Electromagnetic Models of the Human Head

Anwander A.1, Haueisen J.2, Kruggel F.3, Svensen M.1, Wolters C.H.1

1 Max-Planck-Institute of Cognitive Neuroscience, Leipzig, 2 Biomagnetic Center, Friederich-Schiller-University Jena, 3 University of California, Irvine

Electro (Magneto) encephalography yields time-dependent potential (field) distributions on the human scalp. To find the sources due to these maps, a so-called inverse reconstruction has to be performed that requires the repeated simulation of the field distribution for a given set of dipolar sources in the human brain using a volume-conduction model of the head.

field_left field_right
As accuracy plays an important role in neurobiological research, the inclusion of individual structural and physiological information, e.g., tissue conductivity and anisotropy, in the model is of great importance. A new approach was developed for determining the individual directionally dependent conductivity of skull and brain white matter, based on multimodal MRI data. This information was used to set-up individual electromagnetic models of the human head through high resolution finite element techniques. The corresponding sparse, large-scale, linear equation system must be solved for many different source configurations. Our solution is based on a parallel algebraic multigrid method, resulting in very short computation times by combining multigrid solver techniques and parallelization on distributed memory computers. This iterative solver approach is stable towards modeling of tissue anisotropy. The figure above shows the reconstructed source potential map for left (right) medial nerve stimulation in a rat.


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Wolters C., Hartmann U., Koch M., Kruggel F., Burkhardt S., Basermann A., Tuch D.S., Haueisen J. (2001) New Methods for Improved and Accelerated FE Volume Conductor Modelling in MEG/EEG Source Reconstruction. In: Neonen J., Ilmoniemi R.J., Katila T. (eds.), 4th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering (Lisboa), pp. 489-494. Gordon and Breach, ISBN 905-69-9321-6.

Wolters C.H., Anwander A., Koch M.A., Reitzinger S., Kuhn M., Svensen M. (2001) Influence of Head Tissue Conductivity Anisotropy on Human EEG and MEG using Fast High Resolution Finite Element Modeling, based on a Parallel Algebraic Multigrid Solver In: Plesser T., Wittenberg P. (eds.), Forschung und wissenschaftliches Rechnen Vol. 55, pp. 111-156. Gesellschaft für wissenschaftliche Datenverarbeitung, Göttingen.