In animate CC, How do you target a root instance named object inside a function?

Have a html5 canvas document.

I have an object called "brick2" in the root of an animate CC scene (with the same instance name).

Code looks like this:

function moveBrick() {

        this.brick2=0;

    }

var timer1 = setInterval(moveBrick, 100);

this.stop();

When I run the file in a browser the brick doesn't go to "0" x position. However if I write this script (putting the x position property outside the function) it all works fine:

function moveBrick() {       

    }

var timer1 = setInterval(moveBrick, 100);

this.brick.x=0;

this.stop();

Any ideas on what I am doing wrong? Have a real worry that is something completely obvious.