Shadow or not shadow?

I’m using a simple Cube created in maya. I created a kind of curvature map in photoshop because I want to see well defined edges on my cube. All works perfectly except that there is this kind of shadow or ambient occlusion in certain edges and they are very boring. I don’t know if is shadow or AO because even changing the lights nothing change.

msybe it’s important to say that in the screen you see cubes 50x50x50 all aligned that touch each other

Any ideas?

As you can see, in the first image you see the well defined edges
in the 2° the boring shadow/AO
in the 3° and 4° the texture i’m using