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  • (Zombie sounds) Doctor 1: So, how did it get to be this way?

  • Doctor 2: Well, it's my professional opinion that the large gaping bite mark on its shoulder might have something to do with it.

  • D1: Thanks. I mean, what causes its behavioral abnormalities?

  • D2: Well, we know all behaviors are rooted in the brain,

  • so I'd expect that something's gone terribly wrong probably in there.

  • D1: Thanks again, Doctor Obvious.

  • Let me be more specific.

  • What changes in the brain would have to occur in order to cause this kind of behavior?

  • D2: Hmm. Well, let's see.

  • The first thing I notice is how it moves.

  • Stiff legged, with long, lumbering steps, very slow and awkward.

  • Almost like what you'd see in Parkinson's disease.

  • Maybe something's wrong with his basal ganglia?

  • Those are a collection of deep brain regions that regulate movement,

  • through a neurochemical called dopamine.

  • Although most people think of dopamine as the "happy" chemical of the brain,

  • the dopamine-containing neurons in the basal ganglia die off in Parkinson's disease,

  • that's what causes it.

  • Makes it more and more difficult to initiate actions.

  • D1: What?

  • Look again at how it moves. Stiff legs, long stance,

  • These aren't Parkinsonian movements, Parkinson's patients take short, shuffling steps,

  • and the posture's all wrong.

  • This looks to me like what happens when the cerebellum is damaged.

  • The cerebellum's a little cauliflower-shaped area in the back of your head, but don't let its size fool you.

  • That little guy contains almost half of the neurons in the entire brain.

  • Patients who suffer degeneration from this region,

  • something called spino-cerebellar ataxia,

  • show a lack of coordination that results in stiff legs, wide stance, and a lumbering walk.

  • My money's on the cerebellum.

  • D2: Touché. OK. So we've nailed its motor problems.

  • Now what about that whole groaning, lack of talking thing?

  • D1: Hmm. You know, it sounds kind of like expressive aphasia, or Broca's aphasia,

  • which makes producing words difficult.

  • This is caused by damage to the inferior frontal gyrus,

  • or possibly the anterior insula,

  • both regions behind your temple on the left side of your head.

  • D2: I think you're only half right. Zombies definitely can't communicate, that's for sure.

  • But they don't seem to do a good job of understanding things either.

  • Watch this. Hey, Walker! Your father smelt of elderberries!

  • (Laughs) See? No reaction.

  • Either it's not a Monty Python fan, or it can't understand me.

  • I'd say this is like spot-on fluent Wernicke's aphasia,

  • damage to an area at the junction of two of the brain's lobes, temporal and parietal,

  • typically on the left side of the brain, is the culprit.

  • This area is physically connected to Broca's area, that you mentioned,

  • by a massive bundle of neurofibers called the arcuate fasciculus.

  • I hypothesize that this massive bundle of connections is completely wiped out in a zombie.

  • It would be like taking out the superhighway between two cities.

  • One city that manufactures a product,

  • and the other that ships it out to the rest of the world.

  • Without that highway, the product distribution just shuts down.

  • D1: So, basically it's a moot point to reason with a zombie,

  • since they can't understand you, let alone talk back.

  • D2: (Laughs) I mean, you could try, man, but I'm going to stay on this side of the glass.

(Zombie sounds) Doctor 1: So, how did it get to be this way?

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B1 US TED-Ed d1 brain zombie parkinson dopamine

【TED-Ed】Diagnosing a zombie: Brain and body - Tim Verstynen & Bradley Voytek

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    Zenn posted on 2013/04/08
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