Russ,
Interesting results. I'll have to read the paper, but I wonder
how they can speak of rCBF when using fMRI (I guess it must have been
a T1 weighted sequence.) Anyway, making some presumptions about what they
did, some results I've observed seem to be inimical to theirs.
You can check them out if you like at
http://cortex.med.upenn.edu/index_papers.html
Go to the bottom of the screen; the notes are called
"Studies of gain artifacts in fMRI data".
In a nutshell I observed correlations between the mean signal values
and effect sizes (as well as with noise) across subjects. These results
suggest that a time series normalization at each voxel by its mean would
reduce across subject variability in task effects.
Sincerely,
Eric
Eric Zarahn
University Pennsylvania
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