Scientists Study Natures Ability to Create Zombies & Human Uses
December 9, 2012 in Offbeat
Whether humans are susceptible to this sort of zombie invasion is less clear. It is challenging enough to figure out how parasites manipulate invertebrates, which have a few hundred thousand neurons in their nervous systems. Vertebrates, including humans, have millions or billions of neurons, and so scientists have made fewer advances in studying their zombification.
Most of the research on vertebrate zombies has been carried on a single-celled parasite, Toxoplasma gondii. Like thorny-headed worms, it moves between predators and their prey. Toxoplasma reproduces in the guts of cats, which shed it in their feces.
Mammals and birds can pick up the parasite, which invade their brain cells and form cysts. When cats eat these infected animals, Toxoplasma completes its cycle. Scientists have found that Toxoplasma-infected rats lose their fear of cat odor — potentially making them easier prey to catch.
Glenn McConkey of the University of Leeds and his colleagues have found a possible explanation for how Toxoplasma wreaks this change. It produces an enzyme that speeds the production of the neurotransmitter dopamine, which influences mammals’ motivation and how they value rewards. Adding extra dopamine might make Toxoplasma’s hosts more curious and less fearful.