Setup ICA Defaults


The explanation of hidden user interface controls is as follows:

Select Type Of Data Pre-processing - Data is pre-processed prior to the first data reduction. Options are discussed below.
'Remove Mean Per Timepoint' - At each time point, image mean is removed.
'Remove Mean Per Voxel' - Time-series mean is removed at each voxel.
'Intensity Normalization' - At each voxel, time-series is scaled to have a mean of 100. Since the data is already scaled to percent signal change, there is no need to scale the components.
'Variance Normalization' - At each voxel, time-series is linearly detrended and converted to Z-scores.
What Mask Do You Want to Use?
Default Mask
Select Mask
Select Type Of PCA
There are three options like 'Standard' , 'Expectation Maximization' and 'SVD'. Optional parameters for PCA are provided. Please see PCA options page.
Select The Back-Reconstruction Type
Options available are GICA, Regular (GICA2), GICA3 and Spatial-temporal regression. GICA2 and GICA3 are not not shown in the GUI but can be called in the batch script. GICA is a more robust tool to back reconstruct components when compared to GICA2 and GICA3 for low model order.
Note:
Do You Want To Scale Components?
Scale To Original Data(%)
Z-scores
Scaling in Timecourses
Scaling in Maps and Timecourses
Note: By default, subject component images are centered based on the peak of the distribution. Please see variable CENTER_IMAGES in "icatb_defaults.m".
How Many Data Reduction (PCA) Steps Do You Want to Run?
The number of times you want to do PCA.
Note: The number of data reduction steps depends on the number of data sets. A maximum of three data reduction steps is allowed.
Number of PC to reduce each group into
Each subject is reduced to the number of principal components selected.
Note:
  1. Always choose a greater number for PC in the first step if you wish to choose different numbers for the principal components.
  2. The number of principle components after the last step of data reduction (will be disabled as you already entered the number of independent components) is the same as the number of independent components you want to extract.

Figure 1: Setup Defaults menu