[FieldTrip] Problem with tutorial related to parceled brain space

[Xavier Job]

Hi all,

I've noticed something strange in the tutorial "Analysis of auditory evoked
fields in sensor and source space" (
https://www.fieldtriptoolbox.org/tutorial/salzburg/#plot-the-result-in-parceled-brain-space
).

In the section "Localizing auditory evoked fields using beamforming
techniques in parceled brain space", when plotting the source in parceled
brain space, the left/right axis appears to be wrong. The atlas says
'Heschl L', but on the plot it's the right hemisphere. When interactively
clicking on different areas, all right hemisphere areas appear as left
hemisphere labels and vice versa.

I'm also trying to do this analysis on my own data and I get the same
problem. When I plot the beamformer source activity evoked from a tactile
stimulus delivered to the left hand, I get (largely) right SI which makes
sense, but when plotting in parceled brain space this flips to the other
(left) hemisphere, which is definitely wrong.

Perhaps there is a problem with which template file is used for
interpolation in the tutorial? For parceled brain space, the source is
first interpolated using the spm8 template (
*~fieldtrip/external/spm8/templates/T1.nii*), but prior to that it was
interpolated using another template brain (
*~fieldtrip/template/anatomy/single_subj_T1.nii*) for plotting in
'unparceled' space.

Any help with this would be greatly appreciated!

Best,
Xavier

[image: Screenshot 2023-12-01 at 17.15.46.png]
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