[FieldTrip] interpolating source then using sourceplot

[Tyler Grummett]

Hello fieldtrip experts,


I just have a question about source interpolation and sourceplot.


For some reason or another, my data appears to generate a lot of power at  cerebellar regions

and some that dont correspond to any brain regions at all.


So what I tried was to NaN the power that correspond to the cerebellar regions too see if other

brain regions would light up and I still appear to get power at those positions in sourceplot.


Ive made sure that all variables are the same coordinate system and have the same units (spm, mm).


My code is as follows:


% read in mri file

template_mri = ft_read_mri( fullfile( matlabrootpath, 'Matlab', 'fieldtrip', ...
    'template', 'headmodel', 'standard_mri.mat'));
template_mri = ft_convert_coordsys( template_mri, 'spm');
template_mri = ft_volumenormalise( [], template_mri);
template_mri = ft_volumereslice( [], template_mri);


% map beamformer source locations onto an anatomical label in an atlas
cfg = [];
cfg.interpmethod = 'nearest';
cfg.parameter = 'tissue';
sourcemodel2 = ft_sourceinterpolate( cfg, atlas, sourcemodel);

% NaN power at cerebellar regions
temp_source = source;
label = lower( atlas.tissuelabel);
for iii = 91:numel( label),
    atlas_sources = find( sourcemodel2.tissue == iii);
    temp_source.avg.pow( atlas_sources) = NaN;
end

% interpolate source to mri
parameter = 'avg.pow';
cfg            = [];
% cfg.voxelcoord = 'no';
cfg.downsample = 2;
cfg.parameter = parameter;
cfg.interpmethod = 'nearest';
sourceInt  = ft_sourceinterpolate( cfg, temp_source, template_mri);

% Plot interpolated data
plot_method = 'slice';
cfg              = [];
cfg.method       = plot_method; % slice ortho surface
cfg.funparameter = parameter;
cfg.atlas = atlas;
cfg.crosshair = 'yes';
ft_sourceplot( cfg, sourceInt);


Attached is the sourceplot figure that results


Kind regards,


Tyler


*************************

Tyler Grummett ( BBSc, BSc(Hons I))
PhD Candidate
Brain Signals Laboratory
Flinders University
Rm 5A301
Ext 66124
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