Dearest SPM experts,
I have conducted a reinforcement learning experiment and have used a
computational model to create regressors for the fMRI data.
Reading the literature and google-ing spm course ppts I found myself
slightly confused and would simply like to know whether my analysis is
done correctly:
Example:
* For each stimulus presentation (Trial) I have created a regressor
(using a computational model) for the trial Value.
* One column of the design matrix consists of the Trial onset time and
a second column is the parametric modulator Value of the first column.
* To look at the effect of Value, I created a contrast vector for each
participant which is [0 1].
* To see if there is an overall effect of Value over all participants
I conducted a 1-sample ttest using the .con images from the 1st level
analysis.
Is this a correct procedure?
I also have some questions:
* Should I convolve the regressor Value with a HRF function before
enterring it as a parametric modulator?
* What is the difference between a "user-defined regressor" and a
parametric modulator at the 1st level?
Thank you for your help and enjoy your days!
Kristoffer
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