[FieldTrip] only read this is you are doing source reconstruction on eeg data

[Tyler Grummett]

Hi jan,

I accidentally updated without checking what my previous version of field trip was, is there a way of finding out?

Also, if you came from a different toolbox with different electrode positions and copied all the locations from fieldtrip and inserted them, will that cause inaccurate results? I was advised to do this a while ago when I was having issues aligning my electrode positions with fieldtrip's

Tyler



> On 13 Jan 2015, at 1:27 am, Schoffelen, J.M. (Jan Mathijs) <jan.schoffelen at fcdonders.ru.nl> wrote:
> 
> Dear all,
> 
> We have identified and fixed a nasty bug in FieldTrip that has consequences for those who do source reconstruction on EEG data, and have done so using a FieldTrip version of the past month or so. The bug was nasty because it didn’t cause a MATLAB or FieldTrip error.
> 
> Please do read on only if you fulfill following two requirements:
> -you do source reconstruction of EEG data, using FieldTrip, or a toolbox that relies on low level fieldtrip functionality 
> -you have been using a FieldTrip version that’s more recent than December 15, 2014 (svn revision 10043)
> 
> Otherwise, have a nice day :-).
> 
> ….
> 
> ….
> 
> (suspense)
> 
> ….
> 
> (even more suspense)
> 
> ….
> 
> OK, here’s the problem: in order for the EEG source reconstruction to work, the electrodes need to be projected onto the skin surface. In the FieldTrip versions 10043-10093 this projection was incorrect, causing some of the electrodes ending up on wrong locations, causing incorrect forward models (leadfields) and consequently incorrect inverse reconstruction. As of FT-version r.10094 this should be fixed.
> 
> Best wishes and apologies for any inconenience caused,
> 
> Jan-Mathijs
> 
> 
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