It seems zombies aren't just content to infect your brain biologically, they're also eager do it academically.
Academic books about zombies certainly aren't new - take for example Daniel Drezner's Theories of International Politics and Zombies - however, professors Timothy Verstynen and Bradley Voytek may have just released the first book about the complex neurology of the zombie brain.
Titled, Do Zombies Dream of Undead Sheep? A Neuroscientific View of the Zombie Brain, Verstynen and Voytek attempt to explain zombie behavior by looking at the biology of their rotting brains. In a new excerpt published by Slate.com, the duo take a look at explaining the undead's classic shuffling gait. Here is their lengthy argument, broken down by yours truly.
What Are Brains For?
Firstly, the two neuroscientists explain what our brains are actually for. Although they can clearly be used to write Shakespearean sonnets or figure out how to land on the moon, the vast majority of our brain concerns movement. Indeed, some experts suggest the brain originally evolved purely to move us around our environment.
There are some creatures, like the sea squirt (or ascidiacea), which actually digest their brains once they are no longer of use. The sea squirt's first objective in life is to attach itself to a rock. Once it's done that, it no longer has use for its brain and digests it in order to lower its energy requirements. It can then quite happily sit on its rock and catch food that passes by without the need for a whole brain. For Verstynen and Voytek, this process highlights how the brain is essential for movement.
However, unlike sea squirts, zombies cannot wait for food to come to them, so they must move to hunt down their fleshy prey. In this sense, they need to keep their brains - or parts of it - intact.
What Decides Our Movements?
Most of our voluntary movements originate in the neocortex - an area in two of our four major lobes: the frontal lobe and parietal lobe. These then communicate with the motor cortex to put our desired movements into action.
The parietal lobe is mostly concerned with maintaining spatial awareness - spotting things around us and informing our brain of them. The frontal lobe is the decision making center, it decides what to do with the information from the parietal lobe. It then informs the motor cortex, which carries messages to the various muscles and ligaments. Verstynen and Voytek lay out the relationship in the following sketch:
PARIETAL LOBE: “Hey, there’s a tasty piece of broccoli 30 degrees to the left.”
FRONTAL LOBE: “Broccoli??? No way! I want something more awesome!”
PARIETAL LOBE: [sigh] “OK, how about that doughnut 10 degrees to the right?”
FRONTAL LOBE: “Now you’re talking. Hey! Right arm! Attention, right arm! Prepare the triceps, deltoids, and hand muscles for action. We’re going to make a reach.
MOTOR CORTEX: “Jawohl, Lord Frontal Cortex!”
The Zombie Brain
So this just goes to show a lot of stuff is happening in order to make us conduct the most simple actions. If one of these elements fails, or is impaired, it can greatly effect the resulting movement.
So, let's take a look at the zombies' lumbering shuffle. Zombies appear to have trouble performing movements, but not necessarily identifying objects to move towards. In fact, in some stories, their senses have been heightened. The neuroscientists conclude that the zombie's cortical motor systems are mostly intact. The problem hindering their movements must therefore result in the basal ganglia and the cerebellum.
With this in mind, Verstynen and Voytek looked at real life conditions to see if they could figure out what has occurred in the zombie brain. They examined two conditions which are caused by problems in the basal ganglia or cerebellum - Parkinson's disease and spinocerebellar ataxia. Firstly, they looked at Parkinson's Disease, a condition which causes sufferers to develop a slouched posture and a short, shuffling gait. Furthermore, Parkinson's sufferers also have difficulty making movements without obvious goals, meaning the the issue might originate in the parietal lobe and basal ganglia.
Alternatively, spinocerebellar ataxia sufferers adopt a stiff, wide-legged stance and take large, lumbering steps resulting from damage to the cerebellum. However, unlike Parkinson's sufferers, they do not have any issue with initiating movement - just executing it. This suggests their basal ganglia is still functioning properly.
This difference between Parkinson's and spinocerebellar ataxia led the professors to conclude that zombism must affect the undead's brain in a way similar to spinocerebellar ataxia. They concluded the zombie brain may have suffered damage to the cerebellum, although the basal ganglia pathways still seem relatively intact.
An Alternative Solution
Of course, this is all impressive - if slightly unnecessary - work from Verstynen and Voytek. But, it seems George Romero, the modern grandfather of the zombie, has a different explanation for the shambling walk of the undead:
They’re supposed to be dead. They’re stiff. That’s how you’d walk if you were dead
That's much more simple...
Why do you think zombies can't walk properly?