I'm a student working on my bachelor thesis performing independent component analysis (ICA) on some fMRI data using MELODIC FSL.
I would like to ask some questions regarding the results of ICA. Usually I obtain about 50 components per subject but this number varies across subjects and after changing some preprocessing steps as well.
For instance, I obtained a larger number of components (ten more than before) after applying intensity normalization and slice timing correction to the data. My question is what does the number of ICs depend on? Why do some patients have more or less components? If they moved less during the scan, does this mean they will have less components or more?
I would really appreciate if someone could help me figure it out. It would be very useful in order to understand the differences between obtaining a larger or smaller number of components from ICA.