Free will or a parasite controlling your behaviour
There are all sorts of parasites out there that get into some organism, and what they need to do is parasitize the organism and increase the likelihood that they, the parasite, will be fruitful and multiply, and in some cases they can manipulate the behavior of the host.
…here’s this barnacle that rides on the back of some crab and is able to inject estrogenic hormones into the crab if the crab is male, and at that point, the male’s behavior becomes feminized. The male crab digs a hole in the sand for his eggs, except he has no eggs, but the barnacle sure does, and has just gotten this guy to build a nest for him.
The normal life cycle for Toxo is one of these amazing bits of natural history. Toxo can only reproduce sexually in the gut of a cat. It comes out in the cat feces, feces get eaten by rodents. And Toxo’s evolutionary challenge at that point is to figure out how to get rodents inside cats’ stomachs. Now it could have done this in really unsubtle ways, such as cripple the rodent or some such thing. Toxo instead has developed this amazing capacity to alter innate behavior in rodents.
If you take a lab rat who is 5,000 generations into being a lab rat, since the ancestor actually ran around in the real world, and you put some cat urine in one corner of their cage, they’re going to move to the other side. Completely innate, hard-wired reaction to the smell of cats, the cat pheromones. But take a Toxo-infected rodent, and they’re no longer afraid of the smell of cats. In fact they become attracted to it. The most damn amazing thing you can ever see, Toxo knows how to make cat urine smell attractive to rats. And rats go and check it out and that rat is now much more likely to wind up in the cat’s stomach. Toxo’s circle of life completed.
…you might say, okay, well, this is a rodent doing just all sorts of screwy stuff because it’s got this parasite turning its brain into Swiss cheese or something. It’s just non-specific behavioral chaos. But no, these are incredibly normal animals. Their olfaction is normal, their social behavior is normal, their learning and memory is normal. All of that. It’s not just a generically screwy animal.
You say, okay well, it’s not that, but Toxo seems to know how to destroy fear and anxiety circuits. But it’s not that, either. Because these are rats who are still innately afraid of bright lights. They’re nocturnal animals. They’re afraid of big, open spaces. You can condition them to be afraid of novel things. The system works perfectly well there. Somehow Toxo can laser out this one fear pathway, this aversion to predator odors.
…Toxo preferentially knows how to home in on the part of the brain that is all about fear and anxiety, a brain region called the amygdala
…Toxo would take the dendrites, the branch and cables that neurons have to connect to each other, and shriveled them up in the amygdala. It was disconnecting circuits. You wind up with fewer cells there. This is a parasite that is unwiring this stuff in the critical part of the brain for fear and anxiety. That’s really interesting. That doesn’t tell us a thing about why only its predator aversion has been knocked outwhereas fear of bright lights, et cetera, is still in there. It knows how to find that particular circuitry.
So what’s going on from there? What’s it doing? Because it’s not just destroying this fear aversive response, it’s creating something new. It’s creating an attraction to the cat urine.
…there is a well-characterized circuit that has to do with sexual attraction. And as it happens, part of this circuit courses through the amygdala
Now you take Toxo-infected rats, right around the time when they start liking the smell of cat urine, you expose them to cat pheromones, and you don’t see the stress hormone release. What you see is that the fear circuit doesn’t activate normally, and instead the sexual arousal activates some. In other words, Toxo knows how to hijack the sexual reward pathway. And you get males infected with Toxo and expose them to a lot of the cat pheromones, and their testes get bigger. Somehow, this damn parasite knows how to make cat urine smell sexually arousing to rodents, and they go and check it out. Totally amazing.
…And you look in the Toxo genome, and it’s got two versions of the gene called tyrosine hydroxylase. And if you were a neuro-chemistry type, you would be leaping up in shock and excitement at this point.
Tyrosine hydroxylase is the critical enzyme for making dopamine: the neurotransmitter in the brain that’s all about reward and anticipation of reward…Dopamine is about pleasure, attraction and anticipation. And the Toxo genome has the mammalian gene for making the stuff. It’s got a little tail on the gene that targets, specifies, that when this is turned into the actual enzyme, it gets secreted out of the Toxo and into neurons. This parasite doesn’t need to learn how to make neurons act as if they are pleasurably anticipatory; it takes over the brain chemistry of it all on its own.
Look at closely related parasites to Toxo: do they have this gene? Absolutely not…Toxo’s got this one gene which allows it to just plug into the whole world of mammalian reward systems. And at this point, that’s what we know. It is utterly cool.
…people who are Toxo-infected have three to four times the likelihood of being killed in car accidents involving reckless speeding.
On a certain level, this is a protozoan parasite that knows more about the neurobiology of anxiety and fear than 25,000 neuroscientists standing on each other’s shoulders, and this is not a rare pattern. Look at the rabies virus; rabies knows more about aggression than we neuroscientists do. It knows how to make you rabid. It knows how to make you want to bite someone, and that saliva of yours contains rabies virus particles, passed on to another person.
I sat down with a couple of the Toxo docs over in our hospital…one of them jumps up, flooded with 40-year-old memories, and says, “I just remembered back when I was a resident, I was doing a surgical transplant rotation. And there was an older surgeon, who said, if you ever get organs from a motorcycle accident death, check the organs for Toxo. I don’t know why, but you find a lot of Toxo.”
What is the bottom line on this? Well, it depends; if you want to overcome some of your inhibitions, Toxo might be a very good thing to have in your system
Here’s something terrifying and not surprising. Folks who know about Toxo and its affect on behavior are in the U.S. military. They’re interested in Toxo. They’re officially intrigued.
Schizophrenics have higher than expected rates of having been infected with Toxo, and not particularly the case for other related parasites. Links between schizophrenia and mothers who had house cats during pregnancy
Back to dopamine and the tyrosine hydroxylase gene that Toxo somehow ripped off from mammals, which allows it to make more dopamine. Dopamine levels are too high in schizophrenia. That’s the leading suggestion of what schizophrenia is about neurochemically. You take Toxo-infected rodents and their brains have elevated levels of dopamine. Final deal is, and this came from Webster’s group, you take a rat who’s been Toxo-infected and is now at the state where it would find cat urine to be attractive, and you give it drugs that block dopamine receptors, the drugs that are used to treat schizophrenics, and it stops being attracted to the cat urine. There is some schizophrenia connection here with this
- Robert Sapolsky
Related
Are parasites driving your behaviour!
Attacks of the Brain-Controlling Parasites
How Your Cat Is Making You Crazy
What you can learn about the behaviour of dopamine from porn addicts, or any addiction for that matter (see the last bit)
(Source: edge.org)
