Parasites might be controlling your brain

[Nate]

http://www.scientificamerican.com/article.cfm?id=fatal-attraction

Some protozoa infect the brain of their host, shaping its behavior in ways most suited to the pathogen, even if it leads to the suicide of the host

The article is talking about a specific type of parasite, Toxoplasma gondii, which reproduces inside cats, but can be carried by any warm-blooded animal (yep, including humans). Rodents are especially good for the protozoa, because they will take over the rodent's brain and cause it to become "suicidal." Rodents are normally frightened of cats, but this protozoa makes it so it likes cats, even actively seeks them out so that the cat can capture the rodent and eat it, allowing the protozoa to reproduce.

So what is its effect on humans? Well, they're not sure. Research has shown that schizophrenic patients are two to three times as likely as other humans to carry this protozoa...however, correlation does not imply causation, and it's impossible to tell if the protozoa causes schizophrenia, or if people with schizophrenia just have a more hospitable environment and are thus more likely to pick it up. In addition, a prospective study tracking the road safety in Czech recruits during their 18 months of compulsory military draft found a rate of accidents six times higher in affected drivers.

The issue of free will is always a sticky one, and things like this make it even more unclear. What if we're subconsciously being manipulated by brain parasites? It sounds stupid, like fiction, but there are protozoa that can manipulate their hosts into doing things they wouldn't normally do. What if I'm not really making my own decisions? It's disturbing, really.

I hope this doesn't get into free will vs. predestination (that wasn't my intent, if it was I would've posted it in the TD forum), and this isn't dealing with predestination anyway, but rather the concept of free will itself. Oh and brain parasites that control your thoughts. That too. That usually isn't theological.

[ShiroiHikari]

Isn't there a fungus that controls ants or something?

[Nate]

Yep, Cordyceps. It controls ants and causes them to climb a plant and attach themselves to it before they die. The parasite dicrocoelium also has a similar effect on ants, causing them to leave their nest and climb blades of grass and hang off the end with their mandibles so that cows will eat them, where the parasite can reproduce.

Snails are also victims of parasitic mind control, too.

[Sapphire225]

I have heard about Cordyceps, but I'm not too surprised as brain parasites, as one of my friends did let me know how mice can be affected. Also, schizophrenia, are usually caused by the lack of dopamine. I wonder if the parasite serves as a "substitute" in a way, and takes advantage of that. Also, I wouldn't say it has full control over your thoughts, moreso than the perceptions and how it influences your thoughts, like providing the voice in the head of schizophrenia patients, which doesn't make them do the actions but has a strong influence on them. A simple bacteria isn't that smart.

[bobmonkeys]

This sounds like real-life Hinamizawa syndrome.

[shooraijin]

I think it's far more likely that the bug, if even proven to cause clinically relevant disease in immunocompetent hosts, would simply cause disordered behaviour like any other neurodegenerative disorder.

It's easy to burn off some brain tissue and make people act weird, but it's hard to say this is "against their will" in the way most people fear. That requires extremely complex manipulation and I'm unaware of anything in nature that can do that at the scale of the mammalian neocortex. Even the example of the rodent you cite is better explained by their normal fight-flight reflexes being screwed up, which occurs at a much more primal level than intention.

Invertebrate brains are much simpler and very unlike vertebrate brains, making manipulation such as Cordyceps much more feasible.

[ChristianKitsune]

I just can't see a protozoa being intelligent enough to "Control" my brain. So I think I'm with Shooby more here, and this particular parasite probably just messes with the brain tissue enough to make a person act differently.

[Nate]

Even the example of the rodent you cite is better explained by their normal fight-flight reflexes being screwed up, which occurs at a much more primal level than intention.

Well, the article says that the rodents that are infected will still avoid predators that are NOT cats. They'll still flee from humans, for example. That implies something more complex than just screwing up fight-flight reflexes, since otherwise they'd be fine around people too.

The article says the theory seems to be that the protozoa somehow manipulates the regulation of dopamine in the brain, so that when the rodent smells the odor of cat urine or other cat leavings, it releases a pleasurable feeling, so that the rodent wants to be around the area (which is likely to contain a cat, since cats use urine to mark territory). Since other predators don't produce the same scent, the rodent won't stick around since that won't produce a pleasurable response.

Which could still affect humans. If the protozoa manipulates dopamine regulation (again, still theoretical from what the article seems to state) then it's still influencing our thoughts. Not controlling them, obviously, but they're making it more pleasurable to be in dangerous situations perhaps, or maybe they make us feel worse when we do something that could threaten their survivability. It's still pretty disturbing to me, though obviously it's not on the level of turning us into controlled zombies (that part was pretty much just exaggeration).

[ShiroiHikari]

So basically you're saying that "thrillseekers" have brain protozoa telling them that jumping out of planes, bungee jumping, etc. are awesome things to do.

[Rewin]

The only problem with the theory of the parasite causing us to do reckless things is that the parasite has nothing to gain from it. With the rodents it gives itself the greatest opportunity to get to where it can reproduce. A human jumping out of a plane does nothing for the parasite unless the dumb thing thinks there is a horde of cats waiting for it at the bottom of the drop. However, if that part of our brain functions differently than a rodents (which it very likely does, but I don't know) then it could be messing with the wrong part of our brain without knowing it, thus causing these reactions.
But if it's true about the schizophrenia, wouldn't killing the parasite cause relief from the hallucinations and what-not? Seems like that part would be pretty easy to test if that were true.

[Nate]

With all fairness, I don't the protozoa would have the cognizant thought processes necessary to know what kind of animal it was in. If inciting the host to do dangerous things is a key factor in its ability to reproduce, that's what it'll do no matter what kind of animal it's in, since again, it doesn't have a brain capable of going "Wait, this is a human, it won't do any good to put this thing in danger!"

So no, it isn't a problem with the theory, unless you're advocating that the protozoa has a thought process as complex as a human. :p

[Winry]

I didn't read the article, but is the whole idea that protozoa some how alter dopamine levels thus inducing schizophrenia? Just being lazy and not wanting to read the article =P

[Nate]

No, not really, it's just talking about how the protozoa can affect a rodent's behavior so it's more likely to be eaten by a cat, thus furthering its life cycle. It says that people who are schizophrenic are more likely than other humans to have the protozoa in their bodies, but it's unsure what the connection is...at any rate, they're certainly not suggesting that it's the cause of schizophrenia or even necessarily a contributing factor, just that there is a correlation.

[TopazRaven]

Reading this whole thread has certainly set my paranoia level on fire.

[Winry]

Hm, I see. Correlations are tricky things.

[Xeno]

It's "some alien force from outer-space that seeps into the human body and takes over."

[Solid Ronin]

Must kill humans.

[shooraijin]

Well, the article says that the rodents that are infected will still avoid predators that are NOT cats. They'll still flee from humans, for example. That implies something more complex than just screwing up fight-flight reflexes, since otherwise they'd be fine around people too.

The article says the theory seems to be that the protozoa somehow manipulates the regulation of dopamine in the brain, so that when the rodent smells the odor of cat urine or other cat leavings, it releases a pleasurable feeling, so that the rodent wants to be around the area (which is likely to contain a cat, since cats use urine to mark territory). Since other predators don't produce the same scent, the rodent won't stick around since that won't produce a pleasurable response.

Which could still affect humans. If the protozoa manipulates dopamine regulation (again, still theoretical from what the article seems to state) then it's still influencing our thoughts. Not controlling them, obviously, but they're making it more pleasurable to be in dangerous situations perhaps, or maybe they make us feel worse when we do something that could threaten their survivability. It's still pretty disturbing to me, though obviously it's not on the level of turning us into controlled zombies (that part was pretty much just exaggeration).

Oops, I missed that part. But we do already know, and the article makes plain, that rodents react differently to cats in general:

Both species have a deep-seated, innate fear of cats for obvious reasons. Spray a bit of cat urine into a corner, and the rodent will avoid this location, well, like the plague. In contrast, an infected animal loses its innate fear of cats.

This is almost certainly instinctual, not a higher order process (even though rodents do possess a neocortex). Simply playing on that specific pathway is enough; there's no subversion of will -- of whatever sort a rat possesses -- involved.

[TheMewster]

Sorry to distract you from your argument, but can this parasite cause you to think badly (cussing) at things you love? And how does it get transmitted to humans? I'm actually interested in this thread. Thanks and God bless!

[shooraijin]

It's not an argument. *rimshot

Wikipedia has a very nice article on toxoplasmosis: http://en.wikipedia.org/wiki/Toxoplasmosis

Pretty much any brain injury, infectious, traumatic or otherwise, can cause shifts in behaviour. There are many celebrated studies about people taking penetrating or impact injuries to their frontal lobe and losing inhibitions or suffering moderate to extreme changes in personality. Many organic dementias can also make people's behaviour labile. Your specific mention of the sudden use of profanity can be sometimes seen in advancing Alzheimer's, for example.

[MrKrillz0r]

I like how I just read a horror manga about parasites that infects humans and change them. D: *shrugs*

[Atria35]

@ Mewster- What Shooby said. Sudden thoughts of cussing or bad behaviour are not just caused by this parasite. Many of my relatives who have/had Alzheimers started becoming violent and swearing as the disease progressed. My father, who has had a stroke, now has more bad language for the simple reason that the language centers of his brain were highly damaged- he no longer has the vocabulary or self-control to express himself otherwise.

[firestorm]

Okay weird moment here. I'm reading this thread at work when a student asks for me to help them with an assignment. What's the assignment? Their review of a book about an unseen enemy that invades people's bodies and takes over their minds.... creepy. XD

[Dr.Faust]

Oh and let the conspiracy theories roll

[Yamamaya]

Hmmm, I see an excellent way to make use of this parasite.

Complete Global Saturation.

[Sapphire225]

Hmmm, I see an excellent way to make use of this parasite.

Complete Global Saturation.

And soon, we'll all be subordinates of Wesker...which is alright with me!

[ClosetOtaku]

I always thought Kuru was kinda cool.

[Darth_Kirby]

I've been studying the mind abit in a book called Anatomy of the Soul. It's a Christian book written by a psycologist and it takes very seriously the physical asspect of the mind. I think that if such a parasite does infest your brain you will be affected, but the thing that makes humans unique is that they are able to defy their instincts. Any instinct caused by this parasite can be countered by the human mind if you're not just running on emotional auto pilot. In practice it's not always so simple to control your emotions and instincts, but it is something that can be done.

[Atria35]

I've been studying the mind abit in a book called Anatomy of the Soul. It's a Christian book written by a psycologist and it takes very seriously the physical asspect of the mind. I think that if such a parasite does infest your brain you will be affected, but the thing that makes humans unique is that they are able to defy their instincts. Any instinct caused by this parasite can be countered by the human mind if your not just running on emotional auto pilot. In practice it's not always so simple to control your emotions and instincts, but it is something that can be done.

I don't know. That sounds like saying that someone with Alzheimers can stop the mental decline by willpower- I don't believe it can be done.

[Darth_Kirby]

I don't know. That sounds like saying that someone with Alzheimers can stop the mental decline by willpower- I don't believe it can be done.

well... Alzheimers is different. Alzheimers is the slow loss of ones memory over time until you don't even remember how to breath. That is not instinct. That's just flat out mental decay of our physical brain. I was talking about instincts and emotions.