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Subject: comparing timecourses
To: "FSL - FMRIB's Software Library" <[log in to unmask]>
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Hi everybody,
I have a problem regarding the comparison of two different timecourses. One is the timecourse of stimulus onset and the other is the timecourse of response onset. Because the time from stimulus to response varies from trial to trial the shift between the timecourses ist not the same for each trial.
I want to see if they yield different activation. Now I have run both timecourses in one EV models and on visual inspection the activation appears to be somewhat different between the two.
To quantify this difference I have tried to run the two timecourses as EVs in the following two EV model:
EV1: stimulus timecourse
EV2: response timecourse
Contrast 1: EV1=1, EV2=0
Contrast 2: EV1=0, EV2=1
Contrast 3: EV1=1, EV2=-1
The three contrasts all show very little activation and the contrasts 1 and 2 bear no resemblance to the contrasts in the one ev models, which I can't make sense of.
There appears to be some sort of interaction between the contrasts.
Cheers,
Nils
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