Hi there,
I'm hoping to get feedback on my method for seed region selection for a PPI analysis. I first ran a straightforward fMRI analysis for a working memory task, and found two significant clusters (thresholded at Z=2.6, p=.001). As I wanted to get one homogeneous cluster with strong signal, I thresholded the data again at Z=3.7, leaving me with one cluster of 61 voxels for which I extracted the mean timeseries (in every subjects native space) and used this timeseries for the PPI analysis. I chose this approach because I thought this might better capture signal/ be more robust than basing my seed on a peak voxel, even though the latter is suggested in several online tutorials. Can someone explain the pro's and cons of either approach?
Thanks! Kind regards, Dennis
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