[FieldTrip] overlaying beamformer results to native/normalized space
jan.schoffelen at donders.ru.nl
Wed May 11 11:02:49 CEST 2011
On May 4, 2011, at 3:17 PM, Akiko Ikkai wrote:
> I sent a below message to the list last night, but it was bounced
> back. I'm trying from another email account. My apologies if this
> was duplicate...
> I'm trying to run beamformer analysis on my MEG data, using DICS,
> and having difficulty visualizing meaningful results.
> I was able to align MRI image to MEG sensors; after segmentation,
> ft_prepare_singleshell and ft_prepare_leadfield, plotting
> ft_data.grad and volume model confirms that they align reasonably.
> However, using data.grad, grid, and vol to run ft_sourceanalysis,
> and ft_sourceinterpolate with MRI (in ctf coordinate system and
> aligned to MEG sensors) somehow distorts the alignment, and the new
> volume model does not resemble the original.
So, the problem is that ft_sourceinterpolate does not behave as
> I'm assuming that, after ft_sourceinterpolate, if I segment
> source_interpolated.anatomy and run ft_prepare_singleshell and
> ft_prepare_leadfield, it should align with MEG sensors, just as the
> initial volume model aligned with MEG sensors... or am I making too
> much of an assumption here?
Why would you want to do this?
> Because of the misalignment, output data of ft_sourceinterpolate
> with "anatomy" and "avg.pow" does not agree with topoplot (run
> ft_freqanalysis on the same dataset).
> If anyone could explain why this alignment distortion might be
> happening during ft_sourceanalysis and/or ft_sourceinterpolate, I'd
> really appreciate it.
I am afraid you need to be a bit more specific in order for us to
understand what may be going wrong here.
> Thanks in advance, Akiko
> Akiko Ikkai, Ph.D.
> Postdoctoral Fellow
> Department of Psychological and Brain Sciences
> Johns Hopkins University
> Ames Hall, 3400 N. Charles St.
> Baltimore, MD 21218
> fieldtrip mailing list
> fieldtrip at donders.ru.nl
Dr. J.M. (Jan-Mathijs) Schoffelen
Donders Institute for Brain, Cognition and Behaviour,
Centre for Cognitive Neuroimaging,
Radboud University Nijmegen, The Netherlands
J.Schoffelen at donders.ru.nl
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