Scientists Use Quake 2 to Study Mouse Brains

From Slashdot.org:

In this week's issue of Nature, scientists from Princeton University trained
mice to navigate around a virtual environment using a setup that resembles a
combination of a giant trackball and a mini-iMax theater displaying a virtual
world rendered using a modified version of the Quake 2 open source game
engine. (Here's the academic paper, subscription required.) They hold the
mouse's head still atop a giant trackball, which the mouse turns by running. The
scientists use the rotations to move the mouse around in the virtual
environment, and when he reaches certain places, he gets a reward. Because they
are able to hold the head still, they can stick microscopic glass electrodes
into individual neurons in the hippocampus of this mouse as it 'navigates.' They
find the neural activity that resembles activity during real life navigation,
and learned new things about the inputs and computations that are going on
inside these neurons, which weren't known before.

What do you imagine we might learn from such experiments? Anything interesting or useful or practical?