Buzz
Zombies in TV shows and movies often groan, shuffle, and relentlessly pursue brains to devour. But what causes them to behave this way? According to Timothy Verstynen and Brad Voytek, it's a condition called Consciousness Deficit Hypoactivity Disorder.
Verstynen, an assistant professor of psychology at Carnegie Mellon University in Pittsburgh, explains, 'We trick people into learning about neuroscience and its history through zombies.' He moved to Pittsburgh partly because of its connection to George Romero's Night of the Living Dead. The two even showcased the neuroscience behind zombies at ZombieCon 2010 and created a TEDEd presentation about it.
A zombie's primary trait, as anyone familiar with pop culture knows, is its relentless desire for human flesh. Verstynen and Voytek propose that if zombies were real, their insatiable hunger would stem from a malfunctioning hypothalamus, which regulates feelings of fullness. Those with similar brain damage eat endlessly. 'Zombies can't stop eating because they never feel full,' says Verstynen. And they only focus on the immediate task—like chasing after moving food, because they are always hungry.
These shambling undead are notoriously bad at focusing, seemingly only able to pay attention to what’s immediately in front of them, likely due to damage to their parietal lobe. This is akin to Bálint's syndrome, where sufferers can only perceive the most attention-demanding object. For instance, they’ll notice a person darting across the room but miss the group of zombie hunters hiding in the corner. If you ever face a zombie, remember: it’s better to hide than to try running, Verstynen advises.
Zombies walk with a distinct wide-legged, clumsy gait, thanks to spinocerebellar ataxia. This movement disorder, caused by cerebellar damage and atrophy, results in jerky movements, slurred speech, and balance issues. When the researchers met George Romero at ZombieCon, they inquired about the zombies' slow movement, expecting an elaborate explanation. His response? Zombies are dead, so they move stiffly.
Fast zombies, like those in 28 Days Later or World War Z, move at incredible speeds because their resurrection took less time, which Verstynen and Voytek refer to as the resurrection hypothesis. 'Fast zombies have less brain damage than their slower counterparts,' Verstynen explains. This resembles hypoxia, a condition where the brain is deprived of oxygen—the longer the deprivation, the greater the damage.
One characteristic of zombies is their inability to recognize anyone from their past life, a result of prosopagnosia, or face blindness. Additionally, damage to the hippocampus causes retrograde amnesia, meaning zombies experience each day as if it's the same. Essentially, they have no long-term memory.
'Zombies are impulsive and emotionally disturbed,' says Verstynen. But this emotional chaos differs from their memory loss. The researchers believe that if zombies existed, they would have damaged Papez’s circuits, a neural network connecting the amygdala, hippocampus, and limbic system, which is crucial for emotional memory formation. This damage also makes it difficult for zombies to control their anger impulses.
In addition to their rage, zombies struggle to express their frustration verbally due to a malfunctioning arcuate fasciculus, a brain pathway linking two areas responsible for language. Because Broca's area is damaged, zombies can only moan and grunt (perhaps mumbling 'brains'). Furthermore, Wernicke’s area is impaired, making it impossible for them to comprehend mercy pleas from their victims.
Despite the severe impairments in their brains, Verstynen points out that zombies retain their senses and motor functions. 'We wanted the science to be completely authentic,' says Verstynen. He and Voytek, an assistant professor at the University of California, San Diego, are collaborating on a book about the history of neuroscience and the neuroscience of zombies, which Princeton University Press is set to publish next year.
