What do you mean by "AOI" - Area Of Interest? To see the intensity values of the dataset being viewed, you can open the "Define Function" control panel. When all 3 image windows are open, you will see at the bottom of this panel the numbers for the anatomical, functional, and threshold images at the crosshair focus point.
If you turn on the environment variable AFNI_VALUE_LABEL to YES, which can be done in Datamode->Misc->Edit Environment, or in your .afnirc file, then this display info will also be shown even if only 1 image window is open.
Also, you can look at the numbers of the anatomical underlay only using the Graph window, in text mode.
bob cox