Design and user testing processes can sometimes be helped by building functionality into your Axure RP project, just as it would be in the final app.
For example, let's say we want to show a picture of a fruit based on the value selected in a droplist. You could create a dynamic
panel with states containing the images of fruit. When the value of the droplist is changed (OnChange) you can define conditional logic in the cases to evaluate the value in the droplist (if selected option of "Fruit Droplist" equals "apple") and set the dynamic panel state accordingly.