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help > RE: longitudinal gPPI
Nov 23, 2015 08:11 PM | Alfonso Nieto-Castanon - Boston University
RE: longitudinal gPPI
Dear Pauline,
If I am understanding correctly you would want to break down your 6 conditions by session (i.e. instead of A.. F conditions you want to have A_pre... F_pre,A_post...F_post). You could do this manually in Setup.conditions. This is perhaps a bit tedious, to simplify it a bit I would suggest to select your 6 original conditions in the Setup.Conditions tab, right-click on the conditions list and select the 'replicate selected condition as new condition' option. Then rename your original conditions (e.g. conditionA) to conditionA_pre and the new condition to conditionA_post, and then click on all condition*_pre conditions, select the second session and enter [] (empty brackets) in the onset/duration fields, and select all condition*_post conditions, select the first session and enter [] in the onset/duration fields there as well.
Perhaps another alternative (at least for future reference) would be to run the following command when importing your SPM information (instead of clicking on the 'Done' button in the Projects.Import tab):
conn_importspm('', 'breakconditionsbysession',true);
This will import the SPM.mat info to your CONN project but now automatically breaking down your condition information by session.
After any of these steps you should end up with 12 conditions (labeled something like "condition*_pre" and "condition*_post", which (after re-running the Setup/Denoising/First-level steps) you will be able to use to look at pre/post condition differences in connectivity.
Hope this helps
Alfonso
Originally posted by Pauline Favre:
If I am understanding correctly you would want to break down your 6 conditions by session (i.e. instead of A.. F conditions you want to have A_pre... F_pre,A_post...F_post). You could do this manually in Setup.conditions. This is perhaps a bit tedious, to simplify it a bit I would suggest to select your 6 original conditions in the Setup.Conditions tab, right-click on the conditions list and select the 'replicate selected condition as new condition' option. Then rename your original conditions (e.g. conditionA) to conditionA_pre and the new condition to conditionA_post, and then click on all condition*_pre conditions, select the second session and enter [] (empty brackets) in the onset/duration fields, and select all condition*_post conditions, select the first session and enter [] in the onset/duration fields there as well.
Perhaps another alternative (at least for future reference) would be to run the following command when importing your SPM information (instead of clicking on the 'Done' button in the Projects.Import tab):
conn_importspm('', 'breakconditionsbysession',true);
This will import the SPM.mat info to your CONN project but now automatically breaking down your condition information by session.
After any of these steps you should end up with 12 conditions (labeled something like "condition*_pre" and "condition*_post", which (after re-running the Setup/Denoising/First-level steps) you will be able to use to look at pre/post condition differences in connectivity.
Hope this helps
Alfonso
Originally posted by Pauline Favre:
Dear Alfonso,
(thanks for your previous answer)
I'm trying to run a gPPI analysis (6 experimental conditions) with 4 groups scanned two-times (pre/post).
I defined 2 sessions per subject for pre / post, added the corresponding functional and anatomical images and used the SPM.mat of each session to define the conditions.
Everything works well until the second-level analysis where I was not able to define between-sessions contrasts. Indeed, I only get the 6 experimental conditions concatenated across the sessions and not the 6 conditions for each session (which I'd like to compare for specific conditions).
Should I define the different sessions as different subject? (in that case, how can I define within-subject contrasts and be sure that covariance effects are removed?)
Thank you very much for your help,
Best wishes,
Pauline
(thanks for your previous answer)
I'm trying to run a gPPI analysis (6 experimental conditions) with 4 groups scanned two-times (pre/post).
I defined 2 sessions per subject for pre / post, added the corresponding functional and anatomical images and used the SPM.mat of each session to define the conditions.
Everything works well until the second-level analysis where I was not able to define between-sessions contrasts. Indeed, I only get the 6 experimental conditions concatenated across the sessions and not the 6 conditions for each session (which I'd like to compare for specific conditions).
Should I define the different sessions as different subject? (in that case, how can I define within-subject contrasts and be sure that covariance effects are removed?)
Thank you very much for your help,
Best wishes,
Pauline
Threaded View
| Title | Author | Date |
|---|---|---|
| Pauline Favre | Nov 23, 2015 | |
| Alfonso Nieto-Castanon | Nov 23, 2015 | |
| Pauline Favre | Nov 24, 2015 | |
| Alfonso Nieto-Castanon | Dec 2, 2015 | |
| Pauline Favre | Dec 3, 2015 | |