[FieldTrip] ROI selection of beamformer grid points

[Johanna Zumer]

Hi Marieke,

In case you hadn't already, it's easier to do things in MNI coordinates
(like select grid points from atlases) if the source reconstruction was
already done using warped grid points from MNI to subject-specific space.
 See  here
<http://fieldtrip.fcdonders.nl/example/create_single-subject_grids_in_individual_head_space_that_are_all_aligned_in_mni_space?s[]=warp&s[]=mni>for
help on that.   If you have done that, then replace the .pos field in each
subject with the grid.pos from the MNI, and no need to ft_sourceinterpolate.

If the question is more regarding the templates, see here
<http://fieldtrip.fcdonders.nl/template/atlas>for more tips, including info
on the useful ft_read_atlas function.

Cheers,
Johanna




2013/6/26 Marieke van de Nieuwenhuijzen <
m.vandenieuwenhuijzen at fcdonders.ru.nl>

> Dear Fieldtrippers,
>
> I am running my analyses on time courses reconstructed in source space.
> Basically, that means that my working dataset is a matrix of grid point x
> time. What I want to do now is do some analyses on a subset of that
> dataset, a bit analogous to selecting some sensors to restrict analyses to.
> Therefore, what I would ideally want to do, is select a subset of grid
> points corresponding to a specific location (for example only the occipital
> grid points, or only the grid points corresponding to a specific atlas
> label).
>
> Does anyone have any suggestions about how I should go about selecting
> specific grid points? Is there perhaps some grid based atlas, or is it
> possible to select grid points based on their corresponding mni coordinates
> which you get after running ft_sourceinterpolate and ft_volumenormalise (in
> other words, is it possible to reverse ft_volumenormalise and
> ft_sourceinterpolate to map the mni coordinates to the grid points instead
> of the grid points to mni representation).
>
> Any pointers would be much appreciated.
>
> Best,
> Marieke
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