AFNi datasets that have more than one sub-brick (e.g., buckets, 3D+time, fico, ...) are required to have the same geometry in all sub-bricks. Basically, AFNI datasets are 3D or 4D arrays.

Once you select the dataset, you will then get a chooser menu that lets you select which sub-brick to view. For bucket datasets, these choosers are on the "Define Function" control panel (even for the Anat bucket dataset type). For 3D+time datasets, the "Index" chooser at the left-middle of the AFNI controller is what lets you scroll through time.

If you create a bucket dataset with a vast number of sub-bricks, using the menu chooser to select the sub-brick index is difficult or annoying (you'll get a popup menu with 1 item per sub-brick: if you have 500 sub-bricks, this menu can fill the screen or worse). A solution to this problem is to right-click (Button-3) in the label to the left of the menu (for anatomical datasets, that is the "Anat" label). Then you'll get a scrolling popup chooser that lets you select the menu item - since this is presented in a scrolling window, the menu items won't fill up the screen.

bob cox