Inverse solution with only EEG data

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1

Hello,
Is there a reference/function to compute minimum norm source estimates with only EEG data in mne-python?
Thanks!
-Lakshmi
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2

hi,

do you have individual MRI or you want to work with template brain?

the answer is yes you can do both but we need to know to point you in
the right direction.

Best,
A

3

Hi Alexandre,
I do not have individual MRI, so I should go the template brain route I suppose.
Thanks!
-Lakshmi

4

Christian should be able to help.

He wrote the GUI for setting up a template brain.

I would recommend you reproduce first the results on one of
the datasets from the website to get familiar with the concepts,
naming convention and analysis steps.

A

5

Hi,

The reference for the functions to scale MRIs are here: http://martinos.org/mne/stable/python_reference.html#mri-processing. At the top there is a link to slides explaining the coregistration. Let me know if you have any questions.

The easiest way to start the GUI is from the command line:

    $ mne coreg

@Alex: in mne-c, EEG required different arguments for mne_setup_forward_model (no ?homog, http://martinos.org/mne/stable/manual/cookbook.html#setting-up-the-boundary-element-model), how does that work in mne-python?

Christian

6

hi

@Alex: in mne-c, EEG required different arguments for mne_setup_forward_model (no ?homog, http://martinos.org/mne/stable/manual/cookbook.html#setting-up-the-boundary-element-model), how does that work in mne-python?

with make_forward_solution function in mne-python depending if you
pass a bem file that has 3 layers or 1 (ex.
sample-5120-5120-5120-bem-sol.fif vs. sample-5120-bem-sol.fif) it
correspond to non homog (3 layers) vs. homog (1 layer).

Alex

7

So then I think for using the fsaverage brain with EEG you would need to create a new bem model with 3 layers, because fsaverage-inner_skull-bem.fif that comes with mne only has one layer.

Also, Lakshmi, do you have any kind of measurement of the spatial properties of the subjects? head shapes? In order to scale the fsaverage brain for a more realistic head model you would need head shape and/or electrode position measurements. Without any measurements I assume the best you can do is just use the unscaled fsaverage brain(?) in which case we would need canonical electrode positions for fsaverage...

8

Hi Christian,
I don't have measurements of head shape or electrode position.So with the canonical electrode positions what would be my first step?Which tool should I use to compute the bem model with 3 layers?
Thanks!
-Lakshmi

9

Hi Lakshmi,

EEG is much more effected by modelling error than MEG, using standard
electrode position, standard head shape and standard MRI will result in
gross errors in cortical localization, which might make the interpretation
of the results diffcult.

Sheraz