[FieldTrip] ft_sourcestatistics startup memory problem

[Akiko Ikkai]

Hi Johanna & Stephen

It turned out ft_prepare_sourcemodel in the version I was using (20120103)
did not have cfg.grid.template options, so I was never using
"template_grid" to create "grid" in MNI space for each subject. I
downloaded the latest version, ran as you suggested... and victory!

Thank you for your patience. The results look great :)
Akiko


On Tue, Oct 23, 2012 at 4:06 AM, Stephen Whitmarsh <
stephen.whitmarsh at gmail.com> wrote:

> yes, that's the beauty of it!
>
>
> On 23 October 2012 09:08, Johanna Zumer <johanna.zumer at donders.ru.nl>wrote:
>
>> Hi Akiko,
>>
>> The .pos entries are (as expected) different for every subject due to
>> the different coregistration of that subject to the standard MNI.
>> However, the grid positions all originate from the same original
>> MNI-based positions, and are in the same order.  Thus,
>> d1group{1}.pos(1,:) corresponds to the template_grid.pos(1,:) and so
>> forth.   You can substitue d1group{n}.pos=template_grid.pos for all
>> subjects, and then call the stats function, and the results are now in
>> the MNI template grid space.
>>
>> Cheers,
>> Johanna
>>
>> 2012/10/22 Akiko Ikkai <akiko.ikkai at gmail.com>:
>> > Hi Johanna,
>> >
>> > you are right! specifying cfg.grid = grid; was the key;
>> ft_sourceanalysis
>> > for each condition runs to the completion :)
>> >
>> > However, since my data is EEG and the electrode locations vary (hence
>> the
>> > grid coordinates vary) between subjects, running stats across subjects
>> > without normalizing might be causing a problem. For example, the first 3
>> > points in subject1's .pos are (after creating template grid etc.., and
>> run
>> > ft_sourceanalysis using MNI grid):
>> >
>> > d1group{1}.pos(1:3,:)
>> > ans =
>> >    -8.7000   -7.5000   -7.6000
>> >    -7.7000   -7.5000   -7.6000
>> >    -6.7000   -7.5000   -7.6000
>> >
>> > and the same points for the subject2's are:
>> >
>> > d1group{2}.pos(1:3,:)
>> > ans =
>> >    -8.3000   -7.6000   -8.2000
>> >    -7.3000   -7.6000   -8.2000
>> >    -6.3000   -7.6000   -8.2000
>> >
>> > So when I try to run ft_sourcestatistics. I get an error message:
>> > ??? Error using ==> statistics_wrapper at 109
>> > grid locations of the source reconstructions do not match, use
>> > NORMALISEVOLUME
>> > first
>> >
>> > Error in ==> ft_sourcestatistics at 100
>> >     [stat, cfg] = statistics_wrapper(cfg, varargin{:});
>> >
>> > Perhaps I should interpolate and normalize each subject, and run group
>> stats
>> > afterall?
>> >
>> > Thanks! Akiko
>> >
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>
>
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-- 
Akiko Ikkai, Ph.D.
Postdoctoral Fellow
Department of Psychological and Brain Sciences
Johns Hopkins University
Ames Hall, 3400 N. Charles St.
Baltimore, MD 21218
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