[FieldTrip] Align electrods to headmodel with method 'interactiv'

Debora Desideri deb.desideri at gmail.com
Wed Feb 17 11:19:38 CET 2016


Dear Iris,
you should press Y and specify the coordinate system following the
questions that will appear on the command window (you will be asked to
specify whether your coordinate sytsem is ras or lps and so on and where
the origin of the coordinate system is located). afterwards, the GUI will
display the electrodes and the head of the subject as well. You should then
be able to align the electrode by simply applying translation/rotation or
whatever you need make the electrode fit on the head surface.

In case you want to use the methiod 'fiducials', you should have recorded
together with the elctrode positions some anatomical landmarks that you can
easily find in the MRI of the subject. If you did not record such landmarks
during the acquisition of the electrode positions, than I guess your only
option is to use the method 'interactive'

Hope this helps!
Best,
Debora

On Tue, Feb 16, 2016 at 6:07 PM, Steinmann, Iris <
iris.steinmann at med.uni-goettingen.de> wrote:

> Hi FieldTripper,
>
>
>
> I want to do source reconstruction with my EEG data and try to align my
> electrodes to the headmodel (calculated with my own MR data)
>
> (following this description:
> http://www.fieldtriptoolbox.org/example/align_eeg_electrode_positions_to_bem_headmodel)
>
>
>
>
> I run the ft_electroderealign function with the following options:
>
>
>
> cfg = [];
>
> cfg.method    = 'interactive';
>
> cfg.elec      = elec;
>
> cfg.headshape = vol.bnd(1);
>
> elec_new = ft_electroderealign(cfg);
>
>
>
> But all I get is a figure showing a coordinate system with my
> electrodepositions. The scull saved in vol.bnd(1) is not plotted.
>
> (I attached a jpg of the figure).
>
> The MATLAB panel asked me: "Do you want to change the anatomical labels
> for the axes [Y, n]? "
>
> If I say 'no', I get the following error:
>
>
>
> Undefined function or variable 'template'.
>
> Error in ft_electroderealign (line 244)
>
>   for j=1:length(template)
>
>
>
> I tried the ft_electroderealign function with the cfg.method =
> 'fiducials', but ended up with the same figure and the same question in
>
> the MATLAB panel.
>
>
>
> Would be great if someone could help me to figure out what's going wrong
> here and how I can align my electrodes to the headmodel.
>
>
>
> Thanks!
>
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> fieldtrip at donders.ru.nl
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>



-- 

Debora Desideri, PhD Student
BNP Lab - Neurology Department
University Hospital Tübingen
Eberhard Karls University Tübingen
Hoppe-Seyler Str. 3
D-72076 Tübingen
Tel: +49 7071/29 80478
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