sLORETA stat files question

Discussions
1

Dear Brainstorm community,

I created a statistics file comparing sLORETA magnitudes files from different groups. I can now visualize the significant differences between the groups, and there are a few clusters statistically negative and a few positive different in the two groups comparison. How can I get the exact number and location of these vertices?

Thanks,

Boris

2

Hi Boris,

You can first extract a thresholded map from your stat file. Select your results in Process1 and run the process “Test > Apply statistics threshold”.
Then load the output in your Matlab workspace (load or right-click > File > Export to Matlab). Example variable name: sResults.
You can then do something like this:

% Index of the time point of interest, look it up in sResults.Time, or extract the time of interest first
iTime = 1;
% Look for the vertices that have non-zero values
iVertices = find(sResults.ImageGridAmp(:,iTime) ~= 0);
% Number of significant vertices
length(iVertices)
% Load corresponding cortex surface
sSurface = in_tess_bst(sResults.SurfaceFile);
% Get the corresponding locations from the surface file
Vertices = sSurface.Vertices(iVertices,:);

To convert these positions into other coordinate systems:
http://neuroimage.usc.edu/brainstorm/CoordinateSystems#Converting_between_coordinate_systems

Lots of information about manipulating Brainstorm files in scripts:
http://neuroimage.usc.edu/brainstorm/Tutorials/Scripting

Cheers,
Francois