Jquery :: Accessing Object Using Variable String

I have an object whose name is mural. I have assigned the name mural to the title of an anchor element. When user clicks and element I want to store the title of the anchor in a variable called sprite. I then want to access that object whose name corresponds to the sprite variable string.

Here is my code:
HTML Code:
var mural= new Object();
mural.top='0px';
mural.left=-'510px';

var stamps= new Object();
stamps.top='0px';
stamps.left=-'1886px';
var sprite=$(this).attr('title');
$(".image-holder").css("background-position",'sprite.top, sprite.left');

It's not working because the the variable sprite is just a reference to $(this).attr('title'), how do I make it reference the object? Oh and I know that .cc jquery statement probably wont work, I'm not sure yet of the correct way to have two values that don't need quotations in as the second argument.