Dear SPMers
I have an event-related fMRI study with one group of 6 subjects, and 6
conditions repeated in 4 sessions per subject.
1-What is the correct way to see the activation of 1 condition across
subjects?
I did for each subject a model with all 6 conditions in the 4 sessions,
and created 1 contrast per condition across sessions. (each contrast has
four 1’s ).
At the 2nd level I did a separate 1-sample-t-test for each condition.
Alternatively I can do for each subject a separate contrast for each
condition in each session (resulting in 24 contrasts per subject). At the
2nd level I would do a 1-sample-t-test for each condition that includes: 4
contrasts from each subject X 6 subjects. However in this way within
subject variability in mixed with between subject variability at the second
level analysis.
Which is the correct way?
2-What is the correct way to see the shared activation of two conditions
across subjects? How is it possible to do a conjunction analysis of multi-
subjects, when the contrasts are not in the same directory?
Any help will be appreciated
Tali Bitan
Neurobiology dept.
Weizmann Inst.
Israel
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