[FieldTrip] Leadfield magnitude with openmeeg method

[yiye at eln.upv.es]

Dear Colleagues,

 

I attempted to solve volumen conduction problem for another organ rather than brain using openmeeg method. The geometry was expressed in mm. As for conductivity, the leadfield value (magnitude order 10^-5) was about 1000 times higher than expected when I introduced the tissue conductivity in siemen/metre. Then I thought that maybe I should express the conductivity in siemens/mm, and multiplied by 0.001 the tissue conductivity, curiosly the leadfield value increased 1000 times (magnitude order 10^-2). Analogly, when I multiplied by 1000 the tissue conductivity, the leadfield decreased 1000 times (magnitude order 10^-8). This phenomenon is very strange because I expected to have higher surface potential for higher tissue conductivity. The last experiment I did is that I set the tissue resistivity in ohmio.meter in tissue conductivity field, the leadfield value was in expected range. 

The surface potential distribution I obtained was physically interpretable, the surface potential amplitude is the unique issue that generating confusion.

How should I set the tissue conductivity of ft_prepare_headmodel when using openmeeg method?

 

 

Best regards

**********************************

Yiyao Ye Lin 

Universitat Politècnica de València,

Departamento de Ingeniería Electrónica, 

Ed, 7F, 4 planta,

46022, València,

València, España

 

 

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