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.
The output of "3dFDR -help" has some explanation. The method is the basic B-H technique (voxel-wise, not cluster-wise), with an adjustment for estimated fraction of "true negatives". As Rick says, a mask is important to cast out non-brain voxels from the considerations.