[FieldTrip] Problems detecting Artifacts in Neuroscan EEG file

Stephen Politzer-Ahles politzerahless at gmail.com
Tue Oct 4 13:51:14 CEST 2011


Omoniyi,

I've never tried automatic artifact detection in FieldTrip but I remember
when I tried visual artifact rejection on Neuroscan data, I had to change
the Y scale of the plot to make the data show up (the scale that was
necessary for my data was much different than the scale used in the
tutorial, for whatever reason).

Do you need to do artifact detection in FieldTrip rather than Neuroscan? To
be honest, I found it more efficient to do the artifact rejection in
Neuroscan and then import the data into FieldTrip for the more advanced
processing. (But I don't have much experience with using FieldTrip for
artifact rejection, so maybe someone else on the list will have more
suggestions; also, I was only doing visual artifact rejection, so I don't
know if there are differences between doing automatic rejection in Neuroscan
versus FieldTrip.)

Best,
Steve Politzer-Ahles


Message: 1
> Date: Mon, 3 Oct 2011 07:49:27 -0700 (PDT)
> From: Omoniyi Segun <omoniyi_s at yahoo.com>
> To: "fieldtrip at donders.ru.nl" <fieldtrip at donders.ru.nl>
> Subject: [FieldTrip] Problems detecting Artifacts in Neuroscan EEG
>        file
> Message-ID:
>        <1317653367.73347.YahooMailNeo at web65905.mail.ac4.yahoo.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi,
>
>
> I am new to fieldtrip and have been struggling with it for the past four
> weeks.
>
>
> I am trying to do artifact detection using the Automatic Artifact detection
> tutorial on the Site. The first issue I am having is when i set % make the
> process interactive cfg.artfctdef.zvalue.interactive = 'yes';
> I see nothing in the figure that is plotted. I see the data plotted when i
> use the sample data provided but not when i use my Neuroscan EEG data.
>
> Secondly when i click on stop I get the error pasted below.
>
>
>
> ??? Reference to non-existent field 'dimord'.
>
> Error in ==> dimlength at 74
> ????? elseif strcmp(data.(fld), 'rpt_pos')
>
> Error in ==> fixsampleinfo at 31
> ? ntrial = dimlength(data, 'rpt');
>
> Error in ==> ft_checkdata at 579
> ? data = fixsampleinfo(data);
>
> Error in ==> ft_rejectartifact at 203
> ? data = ft_checkdata(data, 'hassampleinfo', 'yes');
>
> Error in ==> do_reject_artifacts at 70
> data_no_artifact_jump = ft_rejectartifact(cfg,artifact_jump);
>
> Error in ==> do_preprocess at 45
> ??????????????? do_reject_artifacts(subject);
>
> I am comfortable making changes to the code and would like some pointers in
> the right direction. I am not sure if this is an issue with Neuroscan data.
>
> Thanks
>
> Omoniyi Segun
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-- 
Stephen Politzer-Ahles
University of Kansas
Linguistics Department
http://www.linguistics.ku.edu/
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