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

History of AFNI updates  

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Frank Bello
March 12, 2005 06:21PM
Hi again,
the deconvolutions came out well! I have a question about a couple of regions that show a clear DEACTIVATION (the hemodynamic response is beefy, but negative-going). The paradigm is the usual: condition1...4, plus some fixations during the ISIs (sequence was optimized etc etc). The noise model is a second order pol. I'm wondering whether this "deactivation" can be interpreted in any meaningful way. One of the issues I have is that all conditions are negative at this location. Say, condition 1 is larger and more negative than condition 2. I can explain this by saying that condition 2 is deactivating this region more than condition 1. But how cannot discount the possibility that the entire deactivation is due to some hydraulic phenomenon (blood being stolen from this region with an overlapping condition effect going in the opposite direction). Furthermore, deactivation relative to what? Since the fixation epochs are not modeled explicitly, I'm not sure... Is it relative to the average of the noise model for the entire scan? Thanks for any suggestions/thoughts.
Subject Author Posted

deactivation & 3dDeconvolve

Frank Bello March 12, 2005 06:21PM

Re: deactivation & 3dDeconvolve

Jed Meltzer March 14, 2005 02:26PM