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
February 24, 2009 05:12PM
Among the SPMG3 basis functions, the 1st one models the basic shape of the HRF, the 2nd one (time derivative) presumably captures the differences in the latency of the peak response (where the peak occurs), and the 3rd one (dispersion derivative) catches the differences in the duration of the peak response (how wide the upstroke spans).

What you're going to do with the 3 basis functions depends on what you care about the HRF. If you're only interested in the basic shape, you can pretty much focus on the 1st basis function. On the other hand, if the subtle difference in terms of HRF shapes is of interest to you, you can use option -iresp in 3dDeconvolve to reassemble the whole HRF for each regressor, and take the reassembled HRFs for group analysis using 3dLME with the approach mentioned on the 2nd half of the following web page:

[afni.nimh.nih.gov]

HTH,
Gang
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Subject Author Posted

Basis Functions

Jatin February 24, 2009 04:34PM

Re: Basis Functions

Gang Chen February 24, 2009 05:12PM

Re: Basis Functions

Jatin February 26, 2009 02:24PM