In class this week, we briefly touched on place cells: hippocampal cells that fire when they detect familiar surroundings, helping us remember and navigate through our environment. During our class discussion on this topic, I immediately started thinking about video games. Playing online multiplayer games is a hobby of mine, and knowledge of the maps these games are played on and their ins and outs is arguably the single most important skill a player can have. I know maps like Nuketown in Call of Duty, Blood Gulch in Halo and Dust in Counter Strike as well as I know my own room. Of course, the difference is that these online maps don’t actually exist. Does spacial memory for these virtual spaces work the same way it does for real spaces? If so, does that mean that I have place cells in my brain that are firing as if I’m running through a real environment when all I’m actually doing is sitting in a chair, staring at a screen and moving my fingers? These are the questions that I heroically set out to answer in this post.
It turns out that the answer to both questions is yes. These answers are clearly demonstrated in this video of a mouse playing Quake II.
Quake II is a first person shooter where players jump around with rocket launchers to kill aliens from the planet Stroggos. The designers of the mouse contraption in the video above, led by molecular biologist David Tank of Princeton, hacked the game to produce a bare-bones environment devoid of hostile aliens for the mouse to run around in. The mouse controls its movement within the game by running along the surface of a styrofoam ball, with the movement of the ball tracked by optical lasers in much the same way that an optical computer mouse works. Without aliens to murder, the mice are incentivized to explore and complete designed mazes with the reward of small sips of water.
So what’s the point of having a mouse play videogames (aside from being objectively hilarious), and how does it relate back to place cells? Studying the activity of place cells at the individual level is a tricky business. Making place cells fire in a mouse’s brain requires that mouse to move around in an environment, which is complicated by the fact that even minor movements could disrupt the one micron thick pipettes needed to observe the electrical activity of a single place cell within the mouse’s brain. By observing that place cells fire while exploring virtual spaces as well as real ones, Tank and his team used Quake II to create a maze through which the mouse could navigate while keeping its head completely still and thus allow for accurate electrical recording. I can extrapolate this information to conclude that my ability to navigate videogame maps with ease is thanks to the same place cells that help me walk across campus or through my apartment without getting lost.