Hi,
This sounds like something that was fixed after the last public
update. There should be a new SPM8 update any day now. Please try
using it and let me know if you still have the problem.
Best,
Vladimir
On Mon, Jan 7, 2013 at 12:34 PM, Lau Møller Andersen
<[log in to unmask]> wrote:
> Dear SPM list
>
> Problem in short:
>
> We have encountered a curious problem regarding our MEG source localisation
> procedure.
> In short, the inverted model returned consists only of NaN's when we run
> group inversion based on the gradiometers. However, it works fine for the
> magnetometers. See general information and detailed description of the
> problem below:
>
> General information about the experiment:
>
> 14 subjects
> Scanned with Elekta equipment (magnetometers and gradiometers)
> ICA applied, eye blink and heart rate components have been removed.
> 306 channels, 326 samples (250 Hz), and 6 conditions.
> SPM-version used: SPM8, revision number 4667 in MATLAB 2011
> Preprocessing: bandpass filtered 0.5 Hz - 15 Hz, epoched (-200 ms - 1100
> ms), robust averaging on each condition, and finally bandpass filter again
> to remove artefacts induced by robust averaging. Conditions have been sorted
> such that D.condlist for each subject is '0', '1', '2', '3', '4', '5'.
> Individual MR-scans obtained for each subject and co-registered to the
> SPM-template.
> New fiducials registered and saved for each subject based on co-registered
> MR-image.
>
>
> Observations concerning the problem:
> Source localisation runs as expected, for all subjects, when only
> magnetometers are used. This is not the case for gradiometers. According to
> our preliminary tests, NaN's are returned whenever we include more than 8
> subjects in our group inversion. It seems to be independent of whether or
> not ICA has been applied or not. Furthermore, we have tested whether it
> could be a single subject that caused NaN's to be returned, but it doesn't
> seem like it.
>
> NaN's returned Subjects included in source localisation after
> having excluded ICA-dependency as the problem
> Yes 1-14 subj > 8
> Yes 1-9 subj > 8
> Yes 2-10 subj > 8
> No 1-8 subj = 8
> No 9-14 subj < 8
> No 2-9 subj = 8
>
> This shows that each subject can be included in a group inversion without
> NaN's being returned. It seems, however, that NaN's are returned whenever
> there are more than 8 subjects in the inversion, which we find a bit
> curious. Our tests cannot exclude that the problem stems from a combination
> of (a) certain subject(s) being included in the group inversion and/or the
> number of subjects being greater than 8.
>
> What we further have investigated:
>
> We have investigated the SPM gain matrices and have observed no obvious
> correlations between successful and unsuccessful inversions (as measured by
> whether or not NaN's occur).
>
> We have investigated whether any subject time series contain curious values
> (e.g. NaN's, inf, NA), and have found none.
>
> We have downloaded the newest version from the SPM-website, revision number
> 4667, and tried the analysis again, where we removed all NIfTI and GIfTI
> images from earlier analyses, but with the same result.
>
> We are open to any suggestions you might have.
>
> Thanks in advance
>
> Michael Nygaard Pedersen and Lau Møller Andersen
>
> P.S. Please make sure that you send answers to the emails of both of us!
>
>
>
>
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