[FieldTrip] Problems with Neuromag Data after SSS

Sun Jun 19 17:20:41 CEST 2011

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
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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
>>
>>
>> _______________________________________________
>> fieldtrip mailing list
>> fieldtrip at donders.ru.nl
>> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
>
> _______________________________________________
> 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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