clarification: coordinates and volumelookup

[Jan Hirschmann]

Sorry, 1 thing to clarify in the last question: By "labelling structures
I recognize works fine" I meant setting power to 1 erverywhere and then
defining a roi, e.g. 'Thalamus' in ft_sourceplot. What I see highlighted
is the thalamus.

 

Best,

Jan

 

________________________________

Von: FieldTrip discussion list [mailto:FIELDTRIP at NIC.SURFNET.NL] Im
Auftrag von Jan Hirschmann
Gesendet: Freitag, 4. Juni 2010 15:21
An: FIELDTRIP at NIC.SURFNET.NL
Betreff: [FIELDTRIP] coordinates and volumelookup

 

Dear all,

 

I am using the function ft_volumelookup with the AFNI atlas to find out
the areas belonging to certain MNI coordinates. Regarding this I have 3
little questions:

 

1)       If I create a grid from template brain T1 (spm2) and multiply
the .pos entries by 10 to convert to mm, as described in the example
matlab scripts on the fieldtrip homepage, the .pos entries are MNI
coordinates, right?

 

2)       When I use volumelookup to look up coordinates (I am giving a
mask as input which really has only 1 nonzero entry) I often get the
result: "no label found". Are there really that many places in the brain
which do not have a label in the atlas?

 

3)       When using the function I get the warning: "homogenous
transformation might be incorrect for AFNI file". Should I worry about
this? Labelling structures I recognize with the tool, e.g. thalamus,
works fine, so I guess labels and cords match.

 

Thanks for your help!

 

Jan

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The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/neuroimaging/fieldtrip.
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