eog artifact rejection

[jan-mathijs schoffelen]

Dear Rodrigo,

It looks as if you are almost there! I suspect the problem occurs  
because you use a version of fieldtrip which cannot do artifact  
identification on data which is already present in memory. This  
version always tries to read in data from a file, and fails in your  
case. Probably the problem solves itself when you download the most  
recent version. I assume that you call artifact_eog as follows: cfg =  
artifact_eog(cfg, data) The second input argument data is of course  
crucial here. Keep up the good work!

Cheers,

Jan-Mathijs




On Mar 25, 2009, at 9:51 PM, Rodrigo A. Montefusco Siegmund wrote:

> Hello everyone
>
> I'm trying to implement a script to detect and remove artifacts.  
> One using
> artifact_eog to eliminate artifacts in the EOG channels. I'm also  
> looking
> to eliminate a very large amplitudes in the signal.
>
> The problem is that the script artifact_eog doesn't work on my dataset
> derived from my own trialfun script.
>
> Error in ==> fieldtrip-20080701\private\filetype at 225
> [p, f, x] = fileparts(filename);
>
> Error in ==> fieldtrip-20080701\private\dataset2files at 66
>   switch filetype(cfg.dataset)
>
> Error in ==> artifact_zvalue at 155
> cfg = dataset2files(cfg);
>
> Error in ==> artifact_eog at 137
>   [tmpcfg, artifact] = artifact_zvalue(tmpcfg);
>
>
> My raw data is obtained from an amplifier built in my laboratory,  
> so we
> collect data very raw, without file header or anything similar.
>
> The file .dat is turned to .mat, then that file is loaded to the
> workspace, and then I process it with my trialfun. with that, I  
> create a
> structure "data" which contains
>
> data =
>        trial: (1x60 cell)
>        label: (1x24 cell)
>      fsample: 250
>         time: (1x60 cell)
>
> in the format for fieldtrip. also generates a hdr
>
> hdr =
>                      Fs: 250
>                  nChans: 24
>                nSamples: 750
>             nSamplesPre: 250
>                 nTrials: 60
>                   label: (1x24 cell)
>          FirstTimeStamp: 1
>      TimeStampPerSample: 1
>
> and the trl that is requested by the documentation.
>
> How can I use the artifact_eog on data generated in the format that I
> mentioned above?
>
> Thanks a lot and excuse my english
>
> best regards
>
> Rodrigo
>
> -- 
> ==============================================================
> Rodrigo A. Montefusco Siegmund
> Doctorado en Ciencias Biomédicas
> Programa de Fisiología y Biofí sica
> I. C. B. M. Facultad de Medicina
> Universidad de Chile
> Centro de Neurociencias Integradas
> Iniciativa Cientí fica Milenio
> Fono: 56 09 82793847
> email:  rmontefusco at med.uchile.cl
> ===============================================================
>
> ----------------------------------
> 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.