[FieldTrip] Running the ICA method to remove EOG/ECG artifact on Neuromag(*.fif) data

[jan-mathijs schoffelen]

Hi Alex,

> it does yes. My question is then how do you compute the withering matrix?

That's the magic of EEGlab ;-). I did not look into the code but I would assume based on the estimate of the precision matrix. Do you think the magnitude problem will lead to numerical issues upon inversion of the covariance matrix?

>> Also can Fieldtrip write data back into fif files keeping intact
>> all the measurement info?
>> 
>> Not really; I have some code of Lauri's (which is not yet in FT), which can
>> write epoched data to a fif-file. However, most of the measurement info is
>> lost along the way.
> 
> that's what I feared.
> 
>> Also, since we're not fif-experts, it's not trivial for
>> us to find out how the measurement info should be formatted. Of course it is
>> possible to reverse engineer this from the mne-code, but this is heavily
>> geared towards elekta hardware. Yet, I could imagine that this functionality
>> could be valuable, because it would enable two-way traffic of data between
>> FT and MNE-suite.
> 
> that would be very valuable indeed.
> 
>> Do you happen to have any code that writes meaningful
>> measurement info?
> 
> not in one function or at least not in matlab.
> 
> one should have a fiff_write_meas_info.m that does the opposite to:
> 
> https://github.com/mne-tools/mne-matlab/blob/master/matlab/fiff_read_meas_info.m
> 
> part of the answer is in:
> 
> https://github.com/mne-tools/mne-matlab/blob/master/matlab/fiff_write_evoked.m
> 
> a python example is in :
> 
> https://github.com/mne-tools/mne-python/blob/master/mne/fiff/meas_info.py#L235
> 
> but I agree you need a fairly good understanding of the fif format…
> 
> we might have to sit down together to do this.

I am afraid so. Well, I would certainly be up for it, because it would further strengthen both packages. Shall I come to you, or will you come to me ;-)?

JM



> Alex
> 
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Jan-Mathijs Schoffelen, MD PhD 

Donders Institute for Brain, Cognition and Behaviour, 
Centre for Cognitive Neuroimaging,
Radboud University Nijmegen, The Netherlands

Max Planck Institute for Psycholinguistics,
Nijmegen, The Netherlands

J.Schoffelen at donders.ru.nl
Telephone: +31-24-3614793

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