Dear Dr. Michimata,
|I am conductiong a fMRI study using a very simple (easy) visual task. TR is
|4.5 sec. The data so far obtained show no activation differences between
|experimental conditions. I suspect that this is because the cognitive load
|of my task is too low. One judgment for every 4.5 sec. is too easy and dull.
|Thus, I want to have my subjects perform two or three trials per a scan. The
|design becomes like a PET study. Is such a multiple-judgments-per-a-scan
|design permitted for fMRI?
Yes, this is perfectly correct. Many blocked designs use ISIs of between 1
and 4 seconds for typical TRs of 3-6 seconds.
best wishes,
Geraint
-----------------------------------------------------------------
Dr. Geraint Rees
Wellcome Advanced Fellow Lecturer
California Institute of Technology Institute of Neurology
Division of Biology 139-74 University College London
Pasadena 12 Queen Square
California 91125 London WC1N 3BG
voice (626) 395-2880 voice (171) 833-7472
fax (626) 796-8876 fax (171) 813-1420
http://www.klab.caltech.edu/~geraint [log in to unmask]
-----------------------------------------------------------------
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|