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example:testing_bem_created_leadfields [2013/08/19 17:20]
217.19.202.94 [Introduction]
example:testing_bem_created_leadfields [2017/08/17 11:21] (current)
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 ===== Introduction ===== ===== Introduction =====
 The following section compares lead fields calculated by means of BEM implementation and theoretical model, by correlating their values for different densities of the head model vertices. It is expected that solutions for a single shell EEG realistic head model converge to the theoretical one with an increasing number of points in the mesh. The following section compares lead fields calculated by means of BEM implementation and theoretical model, by correlating their values for different densities of the head model vertices. It is expected that solutions for a single shell EEG realistic head model converge to the theoretical one with an increasing number of points in the mesh.
-A mesh describing subject'​s head is derived from MRI, in this way: 
-<code matlab> 
- mri = ft_read_mri('​Subject01.mri'​);​ 
- ​cfg ​           = []; 
- ​cfg.method ​    = '​manual';​ 
- bnd = ft_prepare_mesh(cfg,​ mri); 
-</​code>​ 
  
 For the simplest case, the BEM and the theoretical solutions for EEG lead field can be compared directly, because theoretical EEG forward solution for a spherical shell is known. Let's calculate the electric field on top of a sphere, generated by one dipole source with different positions along the z-axis: For the simplest case, the BEM and the theoretical solutions for EEG lead field can be compared directly, because theoretical EEG forward solution for a spherical shell is known. Let's calculate the electric field on top of a sphere, generated by one dipole source with different positions along the z-axis: