[FieldTrip] Problems with Neuromag Data after SSS

Sun Jun 19 21:08:45 CEST 2011

Dear Stephan,

It might be that or that you transferred the files as ascii in FTP
rather than binary. I've seen this error before and showed the file to
Matti Hamalainen. He said the file was corrupted.

Best,

Vladimir

On Sun, Jun 19, 2011 at 4:20 PM, Stephan Moratti <smoratti at psi.ucm.es> wrote:
> Hi Lauren,
> Thanks for your reply. Yes I had it with 6 data sets where SSS was applied.
> I had them copied from the HP workstation to our server and from there to my
> Mac. Could it be a little and big endian thing provoked by moving the files
> from different platforms?
> Stephan
> El 17/06/2011, a las 9:28, Laurence Hunt escribió:
>
> Hi Stephan,
> Did you do anything else to the data besides applying SSS? I use SSS on all
> my data and haven't encountered this problem before. Does it apply to all
> your datasets or just one specific file?
> Laurence
> ===========================================
> Laurence Hunt, DPhil Student
>  Centre for Functional MRI of the Brain (FMRIB),
> University of Oxford
> lhunt at fmrib.ox.ac.uk
> Phone: (+44)1865-(2)22738
> ===========================================
> On 17 Jun 2011, at 08:01, Stephan Moratti wrote:
>
> Hello everybody,
> I had no problems reading Neuromag data, but when I want to read data
> treated with SSS I get the following error:
> ??? Error using ==> fiff_read_tag at 232
> Cannot handle other than dense or sparse matrices yet
> Error in ==> fiff_open at 80
>     tag = fiff_read_tag(fid,dirpos);
> Error in ==> fiff_read_meas_info at 82
>     [ fid, tree ] = fiff_open(source);
> Error in ==> ft_read_header at 1049
>     orig = fiff_read_meas_info(filename);
> Error in ==> mytrialfun_Neuromag_face at 3
> hdr = ft_read_header(cfg.dataset);
> Error in ==> ft_definetrial at 139
>     trl   = feval(cfg.trialfun, cfg);
> Any idea, what I could do?
> Best,
> Stephan
>
> El 17/06/2011, a las 0:37, Rodolphe Nenert escribió:
>
> Im still afraid that the power of this analysis will be very low.
> Maybe you can try an ICA on your fMRI data and try to correlate each
> component with your EOG timecourse.
> Rodolphe N.
>
> On Thu, Jun 16, 2011 at 1:16 PM, frank at greenant.net <fieldtrip at greenant.net>
> wrote:
>>
>> It's a bit of a unique experiment, we're trying to use an ECG machine
>> to acquire EOG, so it's only a single output channel.
>> i guess what I need is a temporal ICA rather than a spatial one...
>> On 17/06/2011, at 2:48 AM, Rodolphe Nenert wrote:
>>
>> To summarize, the ICA will decompose your signal into as many components
>> as Electrodes.
>> Therefore, trying to decompose only one source is useless.
>> Did you use a full net of electrodes into your MRI machine or only EOG
>> electrodes?
>> Hope this helps,
>> Rodolphe N.
>>
>> On Thu, Jun 16, 2011 at 11:42 AM, frank at greenant.net
>> <fieldtrip at greenant.net> wrote:
>>>
>>> I am trying to use fieldtrip to filter EOG data obtained in an MRI.
>>> I want to be able to spot the saccades in the samples and ideally measure
>>> their onset at the
>>> end of each trial.
>>>
>>> As you may guess, it's quite noisy and it's broad spectrum noise, despite
>>> pre-filtering.
>>>
>>> Ideally, I would like to isolate the component that corresponds to the
>>> MRI interference
>>> and then filter this out.
>>>
>>> I have managed to import the data and can run ft_componentanalysis
>>> but it fails with:
>>>
>>> runica() - data size (1,30720) too small
>>>
>>> My data is single channel, 40 epochs, each of 6 seconds (time locked to
>>> stim onset but not saccade onset)
>>> Is there a different method I should be using?
>>>
>>> I have posted some sample data and the current script (which reads in the
>>> data and runs preprocessing) to the following urls:
>>>
>>> http://greenant.net/temp/1_2_MRI_2011-04-29%2016:19:33.mat
>>> http://greenant.net/temp/EOG_analysis.m
>>> _______________________________________________
>>> fieldtrip mailing list
>>> fieldtrip at donders.ru.nl
>>> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
>>
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>
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> ________________________________________________________
> Stephan Moratti, PhD
>
> see also: http://web.me.com/smoratti/
>
> Universidad Complutense de Madrid
> Facultad de Psicología
> Departamento de Psicología Básica I
> Campus de Somosaguas
> 28223 Pozuelo de Alarcón (Madrid)
> Spain
> and
> Center for Biomedical Technology
> Laboratory for Cognitive and Computational Neuroscience
> Parque Científico y Tecnológico de la Universidad Politecnica de Madrid
> Campus Montegancedo
> 28223 Pozuelo de Alarcón (Madrid)
> Spain
>
>
> email: smoratti at psi.ucm.es
> Tel.:    +34 679219982
>
>
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> fieldtrip mailing list
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>
> _______________________________________________
> fieldtrip mailing list
> fieldtrip at donders.ru.nl
> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
>
> ________________________________________________________
> Stephan Moratti, PhD
>
> see also: http://web.me.com/smoratti/
>
> Universidad Complutense de Madrid
> Facultad de Psicología
> Departamento de Psicología Básica I
> Campus de Somosaguas
> 28223 Pozuelo de Alarcón (Madrid)
> Spain
> and
> Center for Biomedical Technology
> Laboratory for Cognitive and Computational Neuroscience
> Parque Científico y Tecnológico de la Universidad Politecnica de Madrid
> Campus Montegancedo
> 28223 Pozuelo de Alarcón (Madrid)
> Spain
>
>
> email: smoratti at psi.ucm.es
> Tel.:    +34 679219982
>
>
>
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