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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bob cox
March 26, 2003 08:53AM
Percent signal change is thought to represent, approximately, the amount of the BOLD effect. If the intrinsic EPI data is 20% less intense in the occipital lobe than the frontal lobe (for example, say due to RF coil nonuniformity), then the amplitude of the signal changes will be 20% less also, all other things being equal. Then the fit coefficient would be smaller, but the percent signal change would be the same.

Thus, it is reasonable to convert to % change when you are formally or informally comparing activations acquired at different locations or in different subjects. Also, it is customary and will be expected by the referees of your paper.

bob cox
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advantages of FIT versus percentage signal change

Andy Lui March 24, 2003 05:28PM

Re: advantages of FIT versus percentage signal change

bob cox March 26, 2003 08:53AM