Do I need ECG channel to run "artifact_ecg"

[jan-mathijs schoffelen]

Dear Jim,

The reason for your crash is probably related to the fact that the
default settings for artifact_ecg have been defined with a ctf-system
in mind. Artifact_ecg will provide some feedback as to how the QRS-
complex-locked MEG signals look, by picking a subset of channels as
defined by cfg.artfctdef.ecg.inspect. By default this is set to all
channels named 'MLTxx'. Since in your megsystem the sensors are named
'Axx', fieldtrip cannot make sense out of the default and crashes.
Just specify your own (subset of) channel(s) to inspect.

Good luck

Jan-Mathijs



On Apr 22, 2009, at 5:23 PM, Jim Li wrote:

> Dear all,
>
>
> W/ a 041809 Fieldtrip, I tried to run the following lines but got
> some error (see
> below). I don't have ECG channel in my data, that's why I use a
> left-most
> MEG channel w/ apparent cardiac interferences instead. Any
> suggestion how
> to fix the problem?
>
> -------------
> cfg                      = [];
> cfg.trl                  = data.cfg.previous.trl;
> cfg.dataset              = data.cfg.previous.dataset;
> cfg.continuous            = 'yes' ;
> cfg.artfctdef.ecg.channel  = 'A229';
> cfg.artfctdef.ecg.pretim = 0.25;
> cfg.artfctdef.ecg.psttim = 0.5;
> cfg.artfctdef.ecg.method  = 'zvalue'; %peak-detection method
> cfg.artfctdef.ecg.cutoff  = 3; %peak-threshold
> [cfg, artifact]          = artifact_ecg(cfg);
>
> current  zvalue threshold = 3.000
> keep the current value (y/n) ?
> y
> ??? Undefined function or variable "labelmlt".
>
> Error in ==> channelselection at 344
> if findmlt,        channel = [channel; labelmlt]; end
>
> Error in ==> artifact_ecg at 238
> sgn    = channelselection(artfctdef.inspect, hdr.label);
>
> ----------------------------------
> 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/neuroimaging/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/neuroimaging/fieldtrip.