Test if there's something at the top of multiple objects?

I'm making a minigame with that has the same mechanics as this game:
https://itunes.apple.com/us/app/flow...526641427?mt=8

But it's a point & click. (Click on a box and a "wire" will be created)

The question is, how am I going to "test" if there's already a wire at the top, bottom, left, right of the wire I created so I can change this wire's animation?

Another example: Minecraft's redstone

Do you want to test if the clicked box already has a wire connected, or to test if there are wires near the clicked box ?

A simple way of doing this would be everytime you click on the box you add one to the alt value A of the box.
then check the value

Alt value a = 1
-change to animation 1

alt value a = 2
-change to animation 2

Hope that helps.