Is tetrodotoxin intoxication the cause of "zombie voice" in Haiti?

What was the main objective of the study, what is nasalization, and what is the zombification process?

Explore zombification process and difference between it in Haiti (seen as magical) vs how US sees it (biological reaction). Look at it from biological perspective

What do the authors think tetrodotoxin (TTX) does in the zombification process vs datura (rich in atropine) do?

Tetrodotoxin: Paralysis. Inhibits action potentials that cause flaccid paralysis. Datura: contributes to hallucinations and state of amnesia.

What is the difference in how people usually get exposed to TTX compared to the zombification process presented in the paper?

Pufferfish being prepared incorrectly and someone ingesting it. Zombification process given non-lethal doses of tetrodotoxin in controlled Voodoo ritual to induce flaccid paralysis and maintaining consciousness. Given through touching it so it is absorbed through the skin.

How does tetrodotoxin’s blockade of voltage-gated sodium channels explain the flaccid paralysis and preserved consciousness described in Haitian zombification?

Sodium ions being blocked not generating action potentials so muscles can’t move resulting in flaccid paralysis. Block voltage gated sodium channels.

How could problems with the vagus nerve or soft palate muscles make someones voice sound more nasal after exposure to tetrodotoxin?

The vagus nerve helps control speech. Soft palate muscles helps separate air from nose and mouth so it goes through one and not both causing you to sound nasally if it goes through both. 

The paper draws parallels between tetrodotoxin poisoning and disorders like botulism. In what ways are their mechanisms similar or distinct in terms of neurotransmission?

Botulism destroys snare proteins causing flaccid paralysis through food or open wounds. TTX entering via breach in skin barrier both affect neuromuscular junction. 

The authors mention persistent oromandibular dystonia and blepharospasms in some survivors. What neural structures might be involved in these chronic symptoms, and how could tetrodotoxin exposure produce long-term dysfunction?

Cranial nerves control facial movements. TTX blocks sodium channels which could lead to uncontrolled movements producing long term dysfunction.

Some people who survived zombification had ongoing facial spasms or strange movements. Why might those effects last?

Irreversible damage to motor cortex or vagus nerves likely from toxin being exposed in neucrotic material (dead tissue). Neuronal death causing changes to motor cortex. Don’t know how much toxin they were exposed to.