Help! I am stuck!

Hi everyone!

I am trying to figure out a way to have text either bold or zoom in when the learner clicks on a shape or rolls over the area that I want highlighted. I am including an attachment to help explain what I am talking about. I need the learner to identify what part of the text I am explaining. I have tried hotspots but can't change the state of what is highlighted. I am stuck. Thanks for your help!