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The Real-Life Neuroscience Behind Zombies

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Most of the zombies you see on television and in movies moan and groan, and pull and tear, and lumber and shuffle, and remain highly focused on finding braiiinns to eat. But why do zombies act the way they do? They suffer from Consciousness Deficit Hypoactivity Disorder, an ailment coined by Timothy Verstynen and Brad Voytek.  

“We are tricking people into learning neuroscience and history of neuroscience by talking about zombies,” says Verstynen, an assistant professor in the psychology department at Carnegie Mellon University in Pittsburgh (knowing that Pittsburgh-native George Romero filmed Night of the Living Dead in the area had just a little to do with him moving there). The two presented the neuroscience of zombies at ZombieCon in 2010 and produced a presentation for TEDEd about it.

As any consumer of pop culture knows, a zombie's main characteristic is its drive to eat human flesh. Verstynen and Voytek say that if they really existed, zombies would be hungry because they have lost some hypothalamic functioning, which controls satiety. People with this kind of damage eat and drink nonstop. “Zombies are constantly trying to eat people because they are never full,” Verstynen says. And they can only focus on the immediate problem—and if that means the food is moving, then zombies are hungry.   

These shuffling undead have terrible attention spans and can only focus on what’s right in front of their faces, likely due to damage in their parietal lobe. They experience something like the real-life Bálint's syndrome, which renders sufferers only able to see the thing that requires the most attention. They observe the person running across the room, not the group of zombie hunters standing in the corner. In case you ever find yourself facing a zombie, keep this in mind: It’s actually better to stop and hide than try to run, Verstynen says. 

When the zombies ruthlessly hunt people, they walk with a specific gait, wide-legged and lumbering, thanks to spinocerebellar ataxia. This movement disorder, caused by damage and atrophy in the cerebellum, contributes to an awkward, halting walk with slurred speech and balance problems. When the duo met Romero at ZombieCon, they asked him why the zombies moved so slowly, assuming he had an elaborate theory. He simply said that zombies were dead so he thought they’d walk stiffly. 

Fast zombies, as seen in 28 Days Later or World War Z, move with such speed because they took less time to resurrect, what Verstynen and Voytek call the resurrection hypothesis. “Fast zombies themselves have less brain damage than the slow ones,” says Verstynen. It’s similar to hypoxia, when the brain is deprived of oxygen. The longer one goes without oxygen, the more damage she will have.

Another notable zombie trait is the inability to recognize anyone from its former life. That’s because zombies suffer from prosopagnosia, otherwise known as face blindness. And damage to the hippocampus causes retrograde amnesia, making every day seem the same. Zombies possess no long-term memories. 

“Zombies are very impulsive and have emotional disruption,” Verstynen says. But this differs from their inability to remember. The duo suspects that if they existed, zombies would have injured Papez’s circuits, a neural highway that connects the amygdala, hippocampus, and limbic system in the brain, and helps with the creation of emotional memories. This damage also means it’s harder for zombies to control their angry impulses. 

On top of this rage, zombies can’t verbally express their angst because of a flawed arcuate fasciculus, which connects two regions of the brain responsible for language. Because Broca’s area fails, zombies can only groan and grunt (and possibly mumble “brains”) while damage in Wernicke’s area makes it impossible for them to understand pleas of mercy from their victims.

While the zombie brain has a lot of problems, Verstynen notes their senses and motor control remain intact. “We wanted the science to be 100 percent real,” Verstynen says. He and Voytek, an assistant professor at the University of California, San Diego, have been working on a book on the history of neuroscience and the neuroscience of zombies, which Princeton University Press will publish next year. 

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What Pop Culture Gets Wrong About Dissociative Identity Disorder
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From the characters in Fight Club to Dr. Jekyll and Mr. Hyde, popular culture is filled with "split" personalities. These dramatic figures might be entertaining, but they're rarely (if ever) scientifically accurate, SciShow Psych's Hank Green explains in the channel's latest video. Most representations contribute to a collective misunderstanding of dissociative identity disorder, or DID, which was once known as multiple personality disorder.

Experts often disagree about DID's diagnostic criteria, what causes it, and in some cases, whether it exists at all. Many, however, agree that people with DID don't have multiple figures living inside their heads, all clamoring to take over their body at a moment's notice. Those with DID do have fragmented personalities, which can cause lapses of memory, psychological distress, and impaired daily function, among other side effects.

Learn more about DID (and what the media gets wrong about mental illness) by watching the video below.

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Scientists Reveal Long-Hidden Text in Alexander Hamilton Letter
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Age, deterioration, and water damage are just a few of the reasons historians can be short on information that was once readily available on paper. Sometimes, it’s simply a case of missing pages. Other times, researchers can see “lost” text right under their noses.

One example: a letter written by Alexander Hamilton to his future wife, Elizabeth Schuyler, on September 6, 1780. On the surface, it looked very much like a rant about a Revolutionary War skirmish in Camden, South Carolina. But Hamilton scholars were excited by the 14 lines of writing in the first paragraph that had been crossed out. If they could be read, they might reveal some new dimension to one of the better-known Founding Fathers.

Using the practice of multispectral imaging—sometimes called hyperspectral imaging—conservationists at the Library of Congress were recently able to shine a new light on what someone had attempted to scrub out. In multispectral imaging, different wavelengths of light are “bounced” off the paper to reveal (or hide) different ink pigments. By examining a document through these different wavelengths, investigators can tune in to faded or obscured handwriting and make it visible to the naked eye.

A hyperspectral image of Alexander Hamilton's handwriting
Hyperspectral imaging of Hamilton's handwriting, from being obscured (top) to isolated and revealed (bottom).
Library of Congress

The text revealed a more emotional and romantic side to Hamilton, who had used the lines to woo Elizabeth. Technicians uncovered most of what he had written, with words in brackets still obscured and inferred:

Do you know my sensations when I see the
sweet characters from your hand? Yes you do,
by comparing [them] with your [own]
for my Betsey [loves] me and is [acquainted]
with all the joys of fondness. [Would] you
[exchange] them my dear for any other worthy
blessings? Is there any thing you would put
in competition[,] with one glowing [kiss] of
[unreadable], anticipate the delights we [unreadable]
in the unrestrained intercourses of wedded love,
and bet your heart joins mine in [fervent]
[wishes] to heaven that [all obstacles] and [interruptions]
May [be] speedily [removed].

Hamilton and Elizabeth Schuyler married on December 14, 1780. So why did Hamilton try and hide such romantic words during or after their courtship? He probably didn’t. Historians believe that his son, John Church Hamilton, crossed them out before publishing the letter as a part of a book of his father’s correspondence. He may have considered the passage a little too sexy for mass consumption.

[h/t Library of Congress]

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