I have a question about using 3dDeconvolve with multiple regressors. I’ve looked through the documentation, but I can’t seem to find the answer. Please feel free to refer me to more information if it is out there. We have a study that has 4 conditions within a run:
A, B, C, D
There are also periods of fixation.
1. Is it necessary to model all the stimuli (i.e., have 4 regressors in one 3dDeconvolve command)?
2. What is 3dDeconvolve using as the “baseline”?
a. For example, if I do put all 4 regressors in – and I look at the activation associated with condition A, is this activation during condition A vs. the activation during any timepoints that are not modeled by
any of the 4 regressors?
b. If so, this would make me think that you need to model all 4 stimuli because if you only modeled 2, then the 2 conditions not modeled would be considered part of the baseline. Is this correct?
Thanks for your help.
Kara