[Mne_analysis] Correspondence of source space with parcellation : another doubt ...

[Eric Larson]

        External Email - Use Caution        

>
> I am still stuck with the correspondence of the source space with
> parcellation.
>

In general, a source space takes the high resolution mesh (~100k verts) and
subselects a small subset of them (~10k or less). The subset is stored in
`src[0]['vertno']` for the left hemi and `src[1]['vertno']` for the right.

Parcellations are generally defined (by FreeSurfer) on the entire high
resolution cortical surface, and thus should contain many more points than
our decimated source space.

So, for a given source space (e.g. ico 4, 2562 sources per hemisphere) I
> would expect to find the vertices 0...2561 in the parcellation.
>

The parcellation can have holes. In the case of "aparc" the medial wall
vertices are missing:

>>> import surfer
>>> brain = surfer.Brain('fsaverage', 'lh', 'white', views='med')
>>> brain.add_annotation('aparc', borders=False)

[image: Screenshot from 2019-09-06 09-58-16.png]

Also keep in mind that the decimated source space vertices being numbered 0
to 2561 is a property unique to `fsaverage` (and how its spherical mesh is
arranged), in general for other subjects these can and will be integers
spanning the whole ~100k brain space.

Eric
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mail.nmr.mgh.harvard.edu/pipermail/mne_analysis/attachments/20190906/51273d8d/attachment-0001.html 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.jpg
Type: image/jpeg
Size: 15760 bytes
Desc: not available
Url : http://mail.nmr.mgh.harvard.edu/pipermail/mne_analysis/attachments/20190906/51273d8d/attachment-0001.jpg 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Screenshot from 2019-09-06 09-58-16.png
Type: image/png
Size: 333943 bytes
Desc: not available
Url : http://mail.nmr.mgh.harvard.edu/pipermail/mne_analysis/attachments/20190906/51273d8d/attachment-0001.png