Parasite Can Control Rodents' Fear of Cats

Rats and mice can be “brainwashed” into liking cat urine, according to a study.

Posted: April 05, 2007, 5 a.m. EST

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(Stock photo)
Rodents can be "brainwashed" to not fear cats, according to a recent study. (Stock photo)
A parasite can control the part of the brain that makes rodents naturally fear cats, according to a new study.

Rats and mice normally flee if they smell cat urine, but the rodents will not run away if they are infected by the protozoan parasite Toxoplasma gondii, according to a study published April 2 by the journal “Proceedings of the National Academy of Sciences.”

The parasite can complete its life cycle only if its rodent host is eaten by a cat. It “hijacks” the rodent’s mind and “brainwashes” the rodent into liking the scent of cat urine, the study concludes.

The parasite seems to reverse the rodent’s innate fear by interfering with conditioned responses in the brain.

The parasite did not affect any other rodent phobias. The parasite is very precise and leaves all other neurological mechanisms for learning to avoid danger intact, according to the study’s leader, Ajai Vyas of Stanford University. Therefore, the rodents learn to survive all hazards except being eaten by cats, which is the only form of death that benefits the parasite.

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Reader Comments

Regina    Germantown, MD

8/19/2008 12:11:35 PM

This is a rather interesting to read. I had a beautiful rat named Humphrey who loved my cat Morris. The two were best friends till one sad day Morris decided to eat the little guy. But still, its a very informative article

Angel    Kalamazoo, MI

4/5/2007 4:16:08 PM

I think anything is possible. I know in humans parasites affect a person's personality. so why not rodents. I had a beautiful rat and he did not have parasites. But he loved my cat Toby. They used to sleep together all the time

Sheryl    Casa Grande, AZ

4/5/2007 10:12:28 AM

Interesting, quirky article.

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