AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

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Gang Chen
December 09, 2003 05:57PM
Hi Shantanu,

In FSL you can run the method of Inter-Repetition Variance Analysis (IRVA) on an event-related task involving several repeated stimuli. Without assuming anything about the shape of the hemodynamic response function, you run ANOVA on the repeated time sequences of the signal intensity, and test the significance at a voxel by comparing the within variance with the between variance.

In terms of no assumption regarding the shape of hrf, AFNI does have such a similar approach by running 3dDeconvolve in its deconvolution mode (instead of its regression mode with outputs from waver), but the underlying mechanism is different in the sense that AFNI still tries to model the hrf in the process. I am not so sure which approach would work better under various circumstances.

Gang
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Inter repition variance analysis

Shantanu December 09, 2003 04:03PM

Re: Inter-repetition variance analysis

Gang Chen December 09, 2003 05:57PM