Issues with OpenMEEG BEM headmodels for sEEG data

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1

I was also wondering whether you were aware of issues in using OpenMEEG BEM headmodels for sEEG data? The sensitivity maps are not coherent with electrode locations.

If so, do you have any pointers as to how to fix this issue? Thanks again.

2

@tmedani, do you know something about this?

@Squiyk, please make a new questions a new topic, so it is easier to find for other users

3

Hi @Squiyk

Can you share an example as a screenshot of this issue?

@Raymundo.Cassani we had this issues with MEG as the MEG uses the integration points and we solved it.
For sEEG and EEG it should work without any issue.

4

Hello,

it seems that the sensitivity is independent of the vertex location. We tried to plot the sensitivity of each channel for each vertex and it is constant.


sHead = in_bst_headmodel('/Users/xc/Documents/brainstorm_db/SPREAD_E2025/data/Sub-05/@rawOC2020UP/headmodel_surf_openmeeg.mat' , 1);

gain    = abs(sHead.Gain(~all(isnan(sHead.Gain),2), :));

figure; hold on;
for iVertex = 1:size(gain,2)

    if ~any(gain(:,iVertex))
        continue;
    end

    plot(1:size(gain,1), gain(:,iVertex), '+')
end

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Here each line is a vertex and each point correspond to a channel in the gain matrix.

5

Something is wrong indeed.

Can you explain the steps you followed to compute the LF?

Can you also check the visualization of the LF with the BST function [Right click on the LF, then view leadfield vectors, and then use the arrows [hit h for more options]]