-12-
¥ STEP 3A: Ignore any
background values in a dataset by creating a mask with 3dAutomask
GValues in the background have very low baseline values,
which can lead to artificially large
percent signal change values.
LetÕs remove them altogether by creating a
mask of our dataset, where values inside the brain are assigned a value of Ò1Ó and values outside of the brain
(e.g., noise) are assigned a value of
Ò0Ó
GThis mask will be used later when the percent signal
change in each voxel is calculated. A percent change will be computed only
for voxels inside the mask
GA mask will be created for each of Subject EDÕs time
shifted, volume registered, and blurred
3D+time datasets:
foreach run (1 2 3
4 5 6 7 8 9 10)
3dAutomask
-prefix mask_r{$run} \
ED_r{$run}_vr_bl+orig
end
åOutput of 3dAutomask: A mask
dataset for each 3D+time dataset:
mask_r1+orig, mask_r2+orig É mask_r10+orig
