neuromag data analysis

Vladimir Litvak v.litvak at ION.UCL.AC.UK
Tue Jan 13 18:34:28 CET 2009


Dear Virginie,

It looks very much like the problem is in your Matlab. The first error
is definitely a result of missing signal processing toolbox. The
second one looks like a version thing, but I'm not sure. If I
understand correctly the third one, it might have to do with the
absence of image processing toolbox that is used to compute clusters.

Best,

Vladimir



On Tue, Jan 13, 2009 at 5:01 PM, Virginie van Wassenhove
<vvw at caltech.edu> wrote:
> Hello Fieldtrip-ers and happy new year!
>
> I am trying to get some Neuromag (MEG) data analysis done with Fieldtrip - so
> far I had used fieldtrip for EEG. I can read the data fine (segmentation via
> meg-pd) but there are a couple of issues now.
>
> 1. when I try to filter or downsample I am receiving the following errors:
>
> %FILTER (lpf specified in cfg)
> blah = timelockanalysis(cfg,data_std_bc);
> the input is timelock data with 306 channels and 801 timebins
> applying preprocessing options
> ??? Undefined function or method 'butter' for input arguments of type 'double'.
>
> Error in ==> preproc_lowpassfilter at 80
>    [B, A] = butter(N, max(Flp)/Fn);
>
> Error in ==> preproc at 360
> if strcmp(cfg.lpfilter, 'yes'),     dat = preproc_lowpassfilter(dat,
> fsample, cfg.lpfreq, cfg.lpfiltord,
> cfg.lpfilttype, cfg.lpfiltdir); end
>
> Error in ==> timelockanalysis at 318
>  [data.trial{i}, data.label, data.time{i}, cfg.preproc] =
> preproc(data.trial{i}, data.label,
>  data.fsample, cfg.preproc, data.offset(i));
> =================================
> %RESAMPLE
> ??? Error: File: isequal.m Line: 1 Column: 1
> The input character is not valid in MATLAB statements or expressions.
>
> Error in ==> checkdata at 145
> if ~isequal(feedback, 'no')
>
> Error in ==> resampledata at 60
> data = checkdata(data, 'datatype', 'raw', 'feedback', 'yes');
>
> =================================
> The data structure looks fine to me:
>
> data_dev1 =
>        hdr: [1x1 struct]
>      label: {306x1 cell}
>      trial: {1x101 cell}
>       time: {1x101 cell}
>    fsample: 1000
>       grad: [1x1 struct]
>        cfg: [1x1 struct]
>
> data_dev1.grad =
>      pnt: [510x3 double]
>      ori: [510x3 double]
>      tra: [306x510 double]
>     unit: 'cm'
>    label: {1x306 cell}
>
>
> Any idea on these error messages?
>
> 2. The second issue is that doing a timelockanalysis on these data returns
> no neg or pos clusters. There is no error message and the computations seem
> to run fine.
>
> Am I missing some steps in the preliminary stages of data analysis for MEG
> in fieldtrip?
>
> Thanks for any help you may provide,
>
> Virginie
>
> ----------------------------------
> 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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