Captivate 12 - How to change object state on slide revisit

I'm using Adobe Captivate 12 and have a Table of Contents slide that serves as a branching one.  Users click the image blocks to visit other slides, then return to the Table of Contents.  Once all images are clicked, the Next button populates and the user can advance.

Currently the images remain in the "Normal" state when the slide is revisited.  I am using variables to get the Next button to populate, so I was trying to use those same variables to change the state of the images to "Visited" after the user has already clicked on them.

I don't see any way to do this in the Slide Interactions or Object Interactions. 

Has anyone figured out how to do this?