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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Ziad Saad
March 20, 2006 11:18AM
Hi Tracy,

As Bob said, the mask should not impact the scaling (normalization) in brain regions. If your mask is too generous, you might have some freakishly large %signal changes outside the brain where the mean signal is close to 0. The safeguard I mentioned in class was to add *step(a-threshold) to your scaling equation, where a is the variable for the voxel's mean and threshold is a cut off you have to set based on the range of values outside the brain. Obviously, threshold should be quite low, something like 0.01 or less.


cheers,
-ziad
Subject Author Posted

how to save voxels when you mask brain

Tracy Jill Doty March 19, 2006 08:14PM

Re: how to save voxels when you mask brain

Zhark March 20, 2006 10:31AM

Re: how to save voxels when you mask brain

Ziad Saad March 20, 2006 11:18AM

Re: how to save voxels when you mask brain

Tracy Jill Doty March 23, 2006 05:18PM

Re: how to save voxels when you mask brain

Daniel Glen March 20, 2006 11:34AM

Re: how to save voxels when you mask brain

Vincent Costa March 21, 2006 06:54PM

Re: how to save voxels when you mask brain

Zhark, Emperor March 21, 2006 07:10PM

Re: how to save voxels when you mask brain

Vincent Costa March 26, 2006 10:02PM

Re: how to save voxels when you mask brain

Zhark March 27, 2006 09:08AM

Re: how to save voxels when you mask brain

Vincent Costa March 27, 2006 11:05AM