DICS pcc error

Jan Mathijs Schoffelen jan.schoffelen at FCDONDERS.RU.NL
Wed Jan 9 08:23:45 CET 2008


Dear Peter,

First, I would advice you to update your fieldtrip-version to a more recent one.

Apparently something is going wrong in read_fcdc_header, and not in the beamformer-algorithm. It seems as if the gradiometer-information in your headerfile (which is the .res4-file in the ctf-dataset) does not contain the information which fieldTrip expects. You might have to look into that. One likely cause is the absence of head-position information in your dataset. As a consequence the gradiometer-info in your .res4-file will only be specified in dewar-coordinates, which makes the dataset useless for source localisation anyway, because the MEG-data cannot be aligned to an anatomical coordinate system.

Yours,

Jan-Mathijs


----- Original Message -----
From: Peter Lin <linpe at NINDS.NIH.GOV>
Date: Tuesday, January 8, 2008 9:34 pm
Subject: [FIELDTRIP] DICS pcc error

> I have a question.  We are trying to process data to use DICS using
> fieldtrip at NIH using CTF system.  In using the pcc script for
> preprocessing, we get this error:
>
> ??? Error using ==> ctf2grad at 68
> unexpected number of coils in MEG channel
>
> Error in ==> read_header at 305
>    hdr.grad = ctf2grad(orig);
>
> Error in ==> read_fcdc_header at 37
> [hdr] = read_header(varargin{:});
>
> Error in ==> preprocessing at 291
> hdr = read_fcdc_header(cfg.headerfile);
>
> In looking at the MEG channels, there are just the standard MEG ref
> channels, EEG channels (6) and MEG channels.  Not sure where the
> program is
> going wrong.  this is 20070204 version of fieldtrip.
>
> Thanks,
>
> peter Lin
> NINDS/NIH
>
> ----------------------------------
> The aim of this list is to facilitate the discussion between users
> of the FieldTrip  toolbox, to share experiences and to discuss new
> ideas for MEG and EEG analysis. See also
> http://listserv.surfnet.nl/archives/fieldtrip.html and
> http://www.ru.nl/fcdonders/fieldtrip.
>

----------------------------------
The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/fcdonders/fieldtrip.



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