[FieldTrip] electrode positions of 4D data

Schönherr, Margit Margit.Schoenherr at uk-erlangen.de
Mon Jul 4 13:37:16 CEST 2011

Hello Yuval,

thank you, giving the electrode labels {'E1', ..., 'En'} reads in the EEG data only (without MEG). But still, I have no electrode positions.

Julian, yes, we have digitized the electrodes, but unfortunately I cannot distinguish the electrode positions in the list of 3000 head shape digitization points. So, this does not solve the problem.


Von: fieldtrip-bounces at donders.ru.nl [fieldtrip-bounces at donders.ru.nl] im Auftrag von Yuval Harpaz [yuvharpaz at gmail.com]
Gesendet: Freitag, 1. Juli 2011 17:12
An: Email discussion list for the FieldTrip project
Betreff: Re: [FieldTrip] electrode positions of 4D data

Dear Margit
with a previous version of fieldtrip I found that not only the location of the electrodes was not in the data structure but also the EEG data. this is when specifying channel = 'EEG'; giving it the channel labels solved it- {'E1' E2' ... 'En'}; if I remember well the elec position was read then. if worse comes to worst you can try reading the EEG location with msi >> matlab<http://biomag.wikidot.com/msi-matlab> tool. I assume the electrodes were digitized.

2011/7/1 Schönherr, Margit <Margit.Schoenherr at uk-erlangen.de<mailto:Margit.Schoenherr at uk-erlangen.de>>

we are using a 4D Neuroimaging device with 248 magnetometers. When reading combined MEG and EEG data sets, there is no elec data structure which would contain information about the electrode positions,labels... At line 161, the ft_read_header function calls

hdr.grad = bti2grad(orig);

which only returns the grad structure, whereas for Neuromag data at line 1056

[hdr.grad, elec] = mne2grad(orig);

has 2 outputs.

There doesn't seem to be anything implemented for getting the electrode positions, is there? I am using fieldtrip-20110603. Is anyone currently working on this, or has already solved the problem?

Thank you,
fieldtrip mailing list
fieldtrip at donders.ru.nl<mailto:fieldtrip at donders.ru.nl>

sent from my 4-year-old PC. poor fellow, only ipod classic, no mail there.


a link to the BIU MEG lab:

"Many were increasingly of the opinion that they'd all made a big mistake in coming down from the trees in the first place. And some said that even the trees had been a bad move, and that no one should ever have left the oceans". Douglas Adams

More information about the fieldtrip mailing list