[Mne_analysis] issue with inverse operator (repost)

[Matti Hamalainen]

Hi Ricky,

Are the MEG data maxfiltered? Sometimes the inverse operator calculation with MEG + EEG does not work correctly if maxfilter is involved. Can you send the screen output of the inverse operator calculation?

- Matti


On Jun 6, 2011, at 11:24 PM, Hari Bharadwaj wrote:

> Hi Ricky,
>   One possibly useful test to see if the issue is related to machine
> precision/round-off related bugs is to apply the inverse operator in
> MATLAB at double precision using mne_ex_compute_inverse().
> 
> If that works fine, then it probably confirms a bug with mne_make_movie.
> If that also looks weird, then it could potentially point to something
> more upstream such as  the SSP (that's used on the data) not being applied
> to the lead field/noise covariance correctly etc..
> 
> Regards,
> Hari
> 
> 
> 
> On Mon, June 6, 2011 3:57 pm, Eric Larson wrote:
>> Assuming you are running linux (are you?), were you able to test it on
>> both x86_64 and i686 versions?
>> 
>> Eric
>> 
>> 
>> On Mon, Jun 6, 2011 at 12:52 PM,  <rsachdev at nmr.mgh.harvard.edu> wrote:
>>> Hello Eric,
>>> 
>>> We tried the stable release and the nightly build.  The stable release
>>> inverse operator seems to work fine but than the issue with the
>>> projection
>>> vectors exists.  With the nightly build, it's the opposite, the inverse
>>> operator gives me the issue and there seems to be no problem with the
>>> EEG
>>> and MEG projection vectors.
>>> 
>>> 
>>> 
>>> 
>>> 
>>>> I had a problem with the EEG projection vectors affecting MEG channels
>>>> as well. However, it only happened on my linux x86_64 install, not on
>>>> a linux i686 install or osx installs. As you note, this channel
>>>> corruption on x86_64 was fixed in a recent nightly. I assume, then,
>>>> that you're running the linux x86_64 nightly?
>>>> 
>>>> If so, one thing you could try is generating your inverses using all
>>>> four combinations of 1) the last stable release and 2) the latest
>>>> nightly combined with 1) the x86_64 linux version and 2) the i686
>>>> linux version. (The i686 linux version should run just fine on 64-bit
>>>> linux installs.) If you can identify which of the four combinations
>>>> suffers from this problem, then it could help narrow down the cause of
>>>> the problem.
>>>> 
>>>> Eric
>>>> 
>>>> 
>>>> On Fri, Jun 3, 2011 at 9:39 AM,  <rsachdev at nmr.mgh.harvard.edu> wrote:
>>>>> Hi all,
>>>>> 
>>>>> It's been a few weeks, and I am still having trouble with this.
>>>>> 
>>>>> There seems to be an issue with the inverse operator from the nightly
>>>>> build version of MNE.  The activation shown on the brain looks unusal.
>>>>>  I
>>>>> am using the nightly build because in the previous versions working
>>>>> with
>>>>> SSP for EEG affected the MEG channels and it was fixed in the nightly
>>>>> build.  Now, I seem to be running into some trouble when using an
>>>>> inverse
>>>>> operator created from both MEG and EEG data, the MEG based inverse
>>>>> operator works/looks fine.  Anyone have any work-arounds or solutions?
>>>>> 
>>>>> Thank you
>>>>> -Ricky
>>>>> 
>>>>> 
>>>>> 
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>>>> 
>>>> 
>>>> 
>>> 
>>> 
>> 
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>> 
> 
> 
> -- 
> Hari Bharadwaj
> _______________________________________________
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> Mne_analysis at nmr.mgh.harvard.edu
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> 

---------

Matti Hamalainen, Ph.D.
Athinoula A. Martinos Center for Biomedical Imaging
Massachusetts General Hospital

msh at nmr.mgh.harvard.edu






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