Dave

In your 4 sided box, insert 4 small triangles against the 4 box sides, which now create 2 paths, a to c, and b to d. Repeat the mouse feeding exercise several times and the mouse will learn how to get to the 4 box corners using the your desired directions. Then remove the 4 triangles and watch what happens. Or, you could eat the bread yourself and feed the mouse to the neighbors cat.