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Creating ROI datasets from Activation Maps
¥The program 3dmerge can find contiguous supra (above) threshold voxel clusters in an activation (functional) map and then convert each cluster into a ROI with a separate data value
HThese ROIs can then be used as starting points for some analysis
H
¥Example:
å3dmerge -1clust_order 1 500
å       -1tindex 1 -1thresh 0.4
å       -prefix ROI_func
å        func+tlrc
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H-1clust_order 1 500: Here weÕve told the program to include voxels as part of a ÒclusterÓ if they are no more than 1mm apart.  The 500 indicates the minimum volume required to form a cluster.  In this example, a cluster is defined by 500 or more voxels grouped together, and each voxel is no more than 1 mm apart from each other
H-1thresh 0.4: Ignore voxels that donÕt survive your threshold (e.g., 0.4) -- the threshold could be any stat you have set, a t-test, an F-value, a correlation coefficient, a mean, etc..