14 DAY TRIAL // A parasite known to the scientific community as Toxoplasma gondii has the ability to toy with a mouse's brain and make the rodent no longer fear cats. What's more, it sometimes causes it to be attracted to these felines, and actively seek their presence.
Recent investigations indicate that this parasite causes permanent structural changes in the rodent's brain. Specifically, the mouse continues to display said abnormal behavior weeks after the parasite left its body.
“Long after we lose the ability to see it [the parasite] in the brain, we still see its behavioral effect,” geneticist Michael Eisen with the University of California, Berkeley explains, as cited by Nature.
In a paper published in the journal PLOS ONE this past September 18, scientists explain that this parasite needs to make the mouse no longer fear cats in order to be able to reproduce.
Thus, Toxoplasma gondii can only reproduce inside a cat's guts. Otherwise put, unless the mouse gets eaten, the parasite does not get the chance to produce a new generation.
Until recently, it was believed that the parasite alters a mouse's behavior by triggering the growth of microscopic cysts inside the cells that make up the rodent's brain.
However, experiments carried out with the help of genetically engineered strains of Toxoplasma gondii indicate that changes in a mouse's brain and the odd behaviors associated with them occur some time before said cysts form, and persist even when the latter are gone.
This suggests that the parasite alters these rodents' behavior through some mechanism that has either very little or nothing to do with the cysts growing inside their brains. Presently, researchers are unable to say what this mechanism is.
What's interesting is that, according to several previous studies, Toxoplasma gondii infects about one-third of people around the world. Besides, human infections with this parasite have been linked with behavioral changes and even schizophrenia.
Scientists hope that, by better understanding how Toxoplasma gondii affects mice, they will be able to shed new light on how it affects humans.