02450nas a2200193   4500008004100000022004300041245011200084210006900196260010700265300001600372490000800388520161600396100001502012700002102027700002402048700002302072700002402095856013702119       2007                        eng d  a0027-8424 (Print); 0027-8424 (Linking)00aBehavioral changes induced by Toxoplasma infection of rodents are highly specific to aversion of cat odors.0 aBehavioral changes induced by Toxoplasma infection of rodents ar  aDepartment of Biological Sciences, Stanford University, Stanford, CA 94305, USA. ajaivyas@stanford.edu  a6442–64470 v1043 aThe protozoan parasite Toxoplasma gondii blocks the innate aversion of rats for cat urine, instead producing an attraction to the pheromone; this may increase the likelihood of a cat predating a rat. This is thought to reflect adaptive, behavioral manipulation by Toxoplasma in that the parasite, although capable of infecting rats, reproduces sexually only in the gut of the cat. The "behavioral manipulation" hypothesis postulates that a parasite will specifically manipulate host behaviors essential for enhancing its own transmission. However, the neural circuits implicated in innate fear, anxiety, and learned fear all overlap considerably, raising the possibility that Toxoplasma may disrupt all of these nonspecifically. We investigated these conflicting predictions. In mice and rats, latent Toxoplasma infection converted the aversion to feline odors into attraction. Such loss of fear is remarkably specific, because infection did not diminish learned fear, anxiety-like behavior, olfaction, or nonaversive learning. These effects are associated with a tendency for parasite cysts to be more abundant in amygdalar structures than those found in other regions of the brain. By closely examining other types of behavioral patterns that were predicted to be altered we show that the behavioral effect of chronic Toxoplasma infection is highly specific. Overall, this study provides a strong argument in support of the behavioral manipulation hypothesis. Proximate mechanisms of such behavioral manipulations remain unknown, although a subtle tropism on part of the parasite remains a potent possibility.1 aVyas, Ajai1 aKim, Seon-Kyeong1 aGiacomini, Nicholas1 aBoothroyd, John, C1 aSapolsky, Robert, M  uhttps://nematoda.myspecies.info/content/behavioral-changes-induced-toxoplasma-infection-rodents-are-highly-specific-aversion-cat-odo