[FieldTrip] Artifacts in sourceplot ortho?

[Charidimos Tzagarakis]

Hi There,
I have been having some problems with the use of sourceplot: I am trying to
display the results of ft_sourcestatistics where input is sources for 2
conditions coming from multiple subjects (individual subjects warped to MNI
space).
To begin with, I interpolate my results to the MNI mri in fieldtrip - eg
for p values :
templatefile = '~/fieldtrip/external/spm8/templates/T1.nii';
template_mri = ft_read_mri(templatefile);
cfg              = [];
cfg.voxelcoord   = 'no';
cfg.parameter    = 'prob';
cfg.interpmethod = 'nearest';
cfg.coordsys     = 'mni';
imgdat = ft_sourceinterpolate(cfg, dat, template_mri);

This seems to work fine except (and this is my question) for some *stange
artifactual voxels* appearing when I use the 'ortho' method (see screenshot
here https://db.tt/W7fiVIWq )
Here is the actual call:

cfg               = [];
cfg.coordsys      = 'mni';
cfg.funparameter  = 'prob';
cfg.maskparameter = cfg.funparameter;
cfg.funcolorlim=[0 0.05];
cfg.opacitymap ='rampdown'
cfg.opacitylim=[0 0.05]
cfg.method='ortho';
cfg.interactive='yes';
cfg.atlas='~/fieldtrip/template/atlas/aal/ROI_MNI_V4.nii';
ft_sourceplot(cfg,imgdat)

I am referring to the "white voxels" that seem to have value of 1 (which I
thought, based on the above call should not be displayed(?)). The same kind
of problem appears when I use other parameters from "prob", eg "stat" .
Those "strange" voxels are always the same. This problem is not present
with eg method "slice"

Any advice or insight you might have would be much appreciated.
Best,
Haris


Charidimos [Haris] Tzagarakis MD, PhD, MRCPsych
University of Minnesota Dept of Neuroscience and Brain Sciences Center
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