I would really appreciate if someone can weight on this: what is the minimum reasonable seed size for resting state fmri (seed to all brain) timeseries extraction. (I’m using HCP ICA cleaned data )
I am trying to correlate tractography findings with resting state fMRI connectivity (seed to all brain) from the thalamus . I have basically parcellated the thalamus using tractography and now I want to see if a similar antero-posterior pattern is maintained also in the cortical networks at rest . I have small masks of about 100 voxels each but when I use 3dmaskave and 3dfim+ the resulting correlation bucket requires a very low threshold of the Afni slider (around .2) to see some activation. Is that expected?
thanks a lot