Under the Hood

Zombie Brains: The Neurological Processes Behind The Behavior Of The Undead

zombie
Why is he chasing people, and why can't he walk right? Pixabay Public Domain

Zombies and brains are inextricably linked. They go together like vampires and blood, or werewolves and the moon. Everyone knows that if the zombie apocalypse ever really hits, we’d have to protect our heads from becoming the next meal for an undead dude. Knowing that brains are a zombie’s favorite snack might be common knowledge, but what about what’s going on in their brains? What is it that makes them insatiably hungry, resistant to pain, and just cognitively,well, not right?

Unfortunately (or fortunately, really), scientists don’t have any real zombies to run tests on or interview about their current mental state — all we can do is hypothesize. But luckily, neurologists know the human brain well enough to guess what the not-so-real zombie brain might look like. Spoiler alert: It isn’t pretty.

Insatiable Hunger

It’s a safe bet that what a zombie is feeling is hungry. All zombies do is eat, and it doesn’t seem to matter if they’ve already consumed half the town — they still want more. This ravenousness isn’t quite normal, and the hypothalamus could be to blame. This part of the brain is responsible for regulating metabolic processes and other basic functions of the human body. Hunger, thirst, body temperature, and sleep are all part of the package, which means that an insatiable hunger could be linked back to this particular brain structure.

More specifically, it is the ventromedial nucleus of the hypothalamus that controls satiety — the feeling of fullness that tells us it’s time to stop eating. Zombies are missing this feeling, so damage to the ventromedial nucleus is a good explanation of the creatures’ need to keep eating.

via GIPHY

Visual Recognition

Another recognizable zombie issue is just that, recognition. If a friend or family member is turned into a zombie, it’s a pretty safe bet they won’t recognize or care who you are afterward. All they see is a human they can eat; they will not see a sister, brother, friend, or loved one.

This lack of recognition resembles a creepy psychiatric disorder called Capgras Delusion, defined as “the false belief that the people you know well have been replaced by imposters.” Though a zombie may not actually care that this has happened, the disorder is the closest human condition to come close to their utter lack of recognition. The delusion is characterized by behavioral issues, and neuroscientists don’t actually have a handle on what causes it. We do know, however, that Capgras delusion is most often seen in patients diagnosed with paranoid schizophrenia and patients suffering from brain injury or dementia.

Movement

If a person is asked to imitate a zombie, one of the key components to the performance is movement. The slow, lumbering, and arms aloft walking may have been abandoned for some modern interpretations of zombies (looking at you The Walking Dead), but classic zombies all moved in a pretty similar way.

Motion is a complex thing to study and attribute to specific brain areas, but there are some spots that are inextricably linked to movement. First up is a collection of smaller areas called the Cortical Motor Areas. Together, they coordinate movement planning, sensory integration, and the actual execution of motion. The second important part of the motor pathway is the basal ganglia, which inhibits actions. Finally, the cerebellum is responsible for coordination and balance — the part of the brain that’s affected when alcohol messes with the way you walk.

According to Verstynen, the type of severe movement disorders seen in a zombies could be explained by severe atrophy of the cerebellum in particular. The odd, off-balance steps and lack of coordination when they attack backs up the idea that zombies are working with a bit less cerebellum function than we are.

via GIPHY

Reactive-Impulsive Aggression

Certainly the most noticeable thing about a zombie is the fact that they want to kill you. And they aren’t going about it in a rational, calm way. This type of mindless violence was described by neuroscientist and Carnegie Mellon professor Timothy Verstynen as reactive-impulsive aggression. Verstynen, who co-authored Do Zombies Dream of Undead Sheep? A Neuroscientific Look at the Zombie Brain with fellow neuroscientist Bradley Voytek, associated this particular category of aggression with zombies because it describes a “subtype of aggression that can result in a sudden, heightened, enduring, or inappropriate aggressive response.”

To end up with this kind of aggression, Verstynen reasons, there has to be something wrong with the prefrontal cortex. Normally, our aggression is regulated by a part of the brain called the orbitofrontal cortex, a higher-level brain area that’s actually in charge of a lot of things. It tells the amygdala, which is associated with fear and emotions, to curb its reactive, primal responses when it isn’t rational or socially acceptable to act upon them. A zombie, however, doesn’t care if what they’re doing is socially acceptable, so atrophy of the prefrontal cortex is a reasonable thing to assume a zombie has. This would leave subcortical processes, including aggressive and reactive behaviors, unconstrained, meaning a zombie would act (uncoordinatedly) on whatever they’re feeling at the moment (probably hungry).

Zombies may not be upon us just yet, but when they do come, at least we know why they’re acting the way they are — not that it would help much.

Loading...