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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carl
September 23, 2003 01:20PM
Hello -

Negative time courses could mean any number of things depending on your paradigm, ROIs, method of extracting the percentage signal etc.

It could also mean that the voxels in the ROI you are looking at operates at a tonically high level during the baseline condition and when an experimental condition forces it to switch off. Given that you have periodicity and not negative 'noise' this may be the case. Marcus Raichles stuff is a must read here - most issues of PNAS during the last 5 years have one of his articles on baseline responses. Jason Mitchell from Dartmouth also published a nice PNAS paper the other month on this. If you cant find it drop me a line and i will email to you.

carl
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negative voxel values

Krista September 23, 2003 01:13PM

Re: negative voxel values

carl September 23, 2003 01:20PM

Re: negative voxel values

bob cox September 24, 2003 11:16AM