Hi,
I am implementing temporal concatentation approach of Melodic in MATLAB
and trying to follow the steps as mentioned in the melodic documentation.
1. Data - Read data for each subject and arrange in time points by voxels.
Time series mean is removed per voxel.
2. a. First PPCA - Stack data of all subjects spatially and compute eigen
vectors. Project data of each subject onto the common eigen space
(Whitening).
b. Second PPCA - Remove mean of timeseries per voxel for each subject's
reduced data. Stack all subjects data temporally and compute eigen vectors.
Project stacked data on to the common eigen space.
3. PICA - Reduced data from the second PPCA step is used to compute
component spatial maps and time courses. Spatial maps thus obtained are
indepenent.
After doing step 2b., group PCA map in my code is not matching the spatial
map obtained using Melodic. Please let me know if I am missing some steps.
Thanks,
Srinivas
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