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Neuron Path Discovery May Change Our Conception of Itching

timothy posted more than 5 years ago | from the just-please-don't-find-the-tickling-paths dept.

Medicine 161

Hugh Pickens writes "Historically, many scientists have regarded itching as just a less intense version of pain, though decades spent searching for itch-specific nerve cells have been unfruitful. Now, Nature reports that neuroscientist Zhou-Feng Chen and his colleagues at Washington University in St. Louis, Missouri have found the first behavioral evidence that there are separate circuits of nerve cells to convey itchiness and pain, and their studies suggest that itch and pain signals are transmitted along different pathways in the spinal cord. 'Most people accept that there are specific, highly specialized neurons for sensations like taste,' says Chen. 'But for pain and itch this is much more controversial.'" (Continues below.)"Two years ago, Chen's group discovered that a cell-surface protein called the gastrin-releasing peptide receptor (GRPR) is important for sensing itchiness but not pain in mice. When Chen and his colleagues destroyed GRPR-bearing neurons by means of a cell toxin, the mice reacted to painful stimuli just like normal mice, licking themselves and flinching or jumping in response to heat, highly irritant chemicals and mechanical pressure. But when the researchers injected the animals with chemicals that normally cause scratching, such as histamine, they barely responded, and the greater the number of GRPR-expressing neurons destroyed, the more subdued was the scratching response."

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Pondering the luck of others (5, Funny)

grub (11606) | more than 5 years ago | (#28982787)


[...] the first behavioral evidence that there are separate circuits of nerve cells to convey itchiness and pain, and their studies suggest that itch and pain signals are transmitted along different pathways in the spinal cord.

This got me thinking...

You know how it is when you're stuck in a conversation at work with Bob the Office Drone and you get a terrible itch building up in waves across your scrotum? The kind that makes you force a smile on your face while you're thinking "Man oh man, I wish Bob would fuck off so I could scratch myself!"

Well... quadriplegics don't get that! Lucky bastards.

Guess I'm a "the glass is 3% full" kind-of-guy.

.

Re:Pondering the luck of others (0, Offtopic)

Anonymous Coward | more than 5 years ago | (#28982831)

Got karma to burn grub? Personally my itch spot is in the rare little fold of skin just at the tip of the coccyx (an inch above the anus). It escalates into burning pain if I sit still on it long enough.

AC obviously

Re:Pondering the fuck of others (-1)

Anonymous Coward | more than 5 years ago | (#28982839)

yo mama almost choked on this dong
when she sucked my dick while singing songs
i have a giant fucking schlong
yo mama rode it all night long

Re:Pondering the luck of others (0, Offtopic)

Fluffeh (1273756) | more than 5 years ago | (#28982923)

Well... quadriplegics don't get that! Lucky bastards.

What if they do get that feeling... but no amount of scratching relieves it? Good god, that would be like... like... being stuck in a wheelchair for the rest of your life! Arghhh!!!

Re:Pondering the luck of others (4, Insightful)

DMUTPeregrine (612791) | more than 5 years ago | (#28983039)

Some do, actually. Phantom Limb syndrome does weird things. The worst bit is it's totally impossible to scratch it.

Re:Pondering the luck of others (1)

nacturation (646836) | more than 5 years ago | (#28983211)

Phantom Scrotum Syndrome?

Re:Pondering the luck of others (1)

ArsenneLupin (766289) | more than 5 years ago | (#28983527)

Phantom Scrotum Syndrome?

Well, just ask any nice lady whether she got it...

Re:Pondering the luck of others (1)

ajseidl (1613911) | more than 5 years ago | (#28983373)

That's Slashdot for you--always breaking new ground. How long before Pfizer has a drug to treat Phantom Testicular Itch? Upside, I suppose they won't have to test for birth defects in test subjects progeny.

Re:Pondering the luck of others (1)

CODiNE (27417) | more than 5 years ago | (#28984227)

If they're only missing one limb then scratching the other side usually makes it stop. Now if you've lost BOTH limbs to that terrible accident then... errrr... well there's always transcendental meditation.

Re:Pondering the luck of others (2, Funny)

dov_0 (1438253) | more than 5 years ago | (#28984589)

you're stuck in a conversation at work with Bob the Office Drone and you get a terrible itch building up in waves across your scrotum? The kind that makes you force a smile on your face while you're thinking "Man oh man, I wish Bob would fuck off so I could scratch myself!"

You wait til people are gone before you scratch?

Re:Pondering the luck of others (1)

budgenator (254554) | more than 5 years ago | (#28984993)

Well... quadriplegics don't get that! Lucky bastards.

Are you sure, quads get phantom limb pain, so I assume phantom limb itching is also likely; imagine an itch that can't be scratched. I burned my hand a few years ago, at the burn clinic they, in a teaching hospital, aways ask about pain, never about itching. Finally one Dr. from another hospital casually mentioned that benedryl would stop the itching. Imagine the gritty itch from a bad sunburn lasting for 3 months, God bless that Dr.

Ouch. Torturous. (3, Insightful)

BobSixtyFour (967533) | more than 5 years ago | (#28982791)

"Mice that had lost the GRPR-producing neurons reacted to painful stimuli just like normal mice, licking themselves and flinching or jumping in response to heat, highly irritant chemicals and mechanical pressure."

Poor mice :(

Re:Ouch. Torturous. (4, Insightful)

DNS-and-BIND (461968) | more than 5 years ago | (#28982929)

If hooking a car battery up to a monkey's brain will help find the cure for AIDS and save somebody's life, I have two things to say... the red is positive and the black is negative.
--Nick Dipaolo

Re:Ouch. Torturous. (4, Insightful)

Rakshasa Taisab (244699) | more than 5 years ago | (#28983005)

Hey, I'd be all ok even if it was your brain being wired up for some car battery shocks.

Re:Ouch. Torturous. (0, Flamebait)

DNS-and-BIND (461968) | more than 5 years ago | (#28983295)

It's even better when you realize that AIDS is a lifestyle disease, like obesity.

Re:Ouch. Torturous. (1)

Nathrael (1251426) | more than 5 years ago | (#28983515)

So if you get raped and get AIDS, it's because of your lifestyle? Damn these girls in their miniskirts. They were asking for it!

Re:Ouch. Torturous. (1)

ArsenneLupin (766289) | more than 5 years ago | (#28983545)

You shouldn't be joking about other peoples' misery.

Re:Ouch. Torturous. (1)

superwiz (655733) | more than 5 years ago | (#28983763)

You shouldn't be joking about other peoples' misery.

"If a bus hits you, it's comedy. If I get a splinter, it's tragedy" -- Mel Brooks

Having said that, the gp was not "joking". He was using a hyperbole to demonstrate a point. While some jokes are hyperbole, not all hyperbole are jokes -- some simply demonstrate a point.

Re:Ouch. Torturous. (1)

ArsenneLupin (766289) | more than 5 years ago | (#28983841)

And his point was?

Millions of people die of AIDS in Africa without doing anything in particular to go looking for it. Thousands got AIDS in France simply by receiving tainted blood transfusions. Millions of babies get it from their mom while still in the womb. Now, please explain, how is that "lifestyle"?

Re:Ouch. Torturous. (1)

shentino (1139071) | more than 5 years ago | (#28984175)

Come to think of it I could say the same thing about how the food industry, particularly fast food, deliberately taints their product to make you fat, hungry, and addicted to the food.

Besides Kevin Trudeau, you should also take a look at Super Size Me, as well as Fast Food Nation, two other authors who have nothing at ALL to do with KT.

Re:Ouch. Torturous. (1)

superwiz (655733) | more than 5 years ago | (#28984177)

Now, please explain, how is that "lifestyle"?

I don't believe I have the burden of proof of that statement. You attacked the style of the statement (hyperbole) by mis-characterizing it as a joke. I explained your mis-characterization. That doesn't mean that I agreed with the content of the statement. Nor does this very comment mean that I disagree with the content of that statement. So far I made no judgment on the content of that statement. And I don't have a burden of proof of a statement on which I made no judgment.

Re:Ouch. Torturous. (1)

Vovk (1350125) | more than 5 years ago | (#28984491)

I don't believe I have the burden of proof of that statement. You attacked the style of the statement (hyperbole) by mis-characterizing it as a joke. I explained your mis-characterization. That doesn't mean that I agreed with the content of the statement. Nor does this very comment mean that I disagree with the content of that statement. So far I made no judgment on the content of that statement. And I don't have a burden of proof of a statement on which I made no judgment.

Aaaaaaah!!! Stop it! You obviously disagreed with

It's even better when you realize that AIDS is a lifestyle disease, like obesity.

But you missed the entire point that it was sarcasm. Then OTHER PEOPLE missed your sarcastic/hyperbolic statement about girls in miniskirts and now there's an entire thread which should be labeled offtopic or troll and it's making my brain hurt :(

hell... the entire thread started off with "poor mice", let's get back to that.

I am 100% for testing on animals if it means we can make advances in medical science. Now, the science of itchiness... I'm quite positive that there is some better project on which these researchers can work.

Re:Ouch. Torturous. (1)

superwiz (655733) | more than 5 years ago | (#28984583)

Aaaaaaah!!! Stop it! You obviously disagreed with

You probably think that because you think that this comment:

So if you get raped and get AIDS, it's because of your lifestyle? Damn these girls in their miniskirts. They were asking for it!

was mine. It wasn't.

hell... the entire thread started off with "poor mice", let's get back to that.

Please!!!

I am 100% for testing on animals if it means we can make advances in medical science.

hear, hear

Now, the science of itchiness... I'm quite positive that there is some better project on which these researchers can work.

That's a common misconception about academic research. It does basic science. So it doesn't try to be "useful". Its aim is (a) to be interesting to the researchers (b) to provide description of natural phenomena without concern for its use. The fact that some of the basic research ends up being useful is purely coincidental.

In this particular case, it's actually not a bad idea to do a a completely exhaustive basic research. Since it's not yet understood how every little detail of a human body works, it's not a bad idea to find out and document all of it. Doing something "useful" with that information is the next stage. But given the interconnected nature of the all the systems in the body, it's a really, really, really good idea to research and document it all.

It's almost guaranteed that someday someone will make a pill for some nasty condition and that pill might accidentally also effect the GRPR-bearing neurons. Because of this research, they'll be able to understand why during clinical trials some patients were found to experience itchiness. It's practically a guarantee that this will happen sooner or later. When it comes to documenting human body, encyclopedic understanding is never a bad idea.

Re:Ouch. Torturous. (4, Insightful)

dcollins (135727) | more than 5 years ago | (#28983109)

"If hooking a car battery up to a monkey's brain will help find the cure for AIDS and save somebody's life, I have two things to say... the red is positive and the black is negative.
--Nick Dipaolo"

What if it's a hundred monkeys? A million monkeys? A billion? What if there's a 5% chance it might help? What if it's a researcher who thinks it might help, but hasn't been right to date?

Re:Ouch. Torturous. (5, Funny)

The_mad_linguist (1019680) | more than 5 years ago | (#28983125)

They're just monkeys.

Lazy bastards haven't finished my copy of Hamlet.

Work harder, you ingrates!

Re:Ouch. Torturous. (1)

overcaffein8d (1101951) | more than 5 years ago | (#28983429)

yes, i had it covered on the infinite amount of monkeys and infinite amount of typewriters, but i must have neglected to get the infinite amount of ink. at least they're not using computers with windows, because then they'd have an infinite number of BSOD

Re:Ouch. Torturous. (1)

z0idberg (888892) | more than 5 years ago | (#28983209)

What if you had AIDS and it might cure you?

Re:Ouch. Torturous. (4, Funny)

TheLink (130905) | more than 5 years ago | (#28983267)

I'm pretty sure that hooking up a car battery to your brain can cure you of AIDS.

The problems are the resulting side effects and reduced longevity.

Re:Ouch. Torturous. (2, Funny)

nacturation (646836) | more than 5 years ago | (#28983221)

What if it's a hundred monkeys? A million monkeys? A billion? What if there's a 5% chance it might help? What if it's a researcher who thinks it might help, but hasn't been right to date?

As long as it's not an infinite number of monkeys brains being bashed in with an infinite number of typewriters because then we'd not only destroy the complete works of Shakespeare, but also the cure for every problem there is.

Re:Ouch. Torturous. (0)

Anonymous Coward | more than 5 years ago | (#28983353)

You need more batteries.

Allow me to connect the memes (1)

bdwoolman (561635) | more than 5 years ago | (#28984197)

The car battery is hooked to the monkey's itchy phantom scrotum.

Now. I want to know.

Who screwed the monkey in the first place and got the first case of AIDS?

Re:Ouch. Torturous. (1)

Krneki (1192201) | more than 5 years ago | (#28984501)

I'm positive this will work, HIV positive.

Re:Ouch. Torturous. (1)

Fluffeh (1273756) | more than 5 years ago | (#28982935)

You should see what they do to test the products we all use everyday. Double ouchies.

Re:Ouch. Torturous. (1)

superwiz (655733) | more than 5 years ago | (#28983773)

Better test them on monkey than on animal rights activists. I would actually be against any animal-rights activists that would volunteer to take a monkey's place in an experiment. Peoples' well-being comes before animals'.

Re:Ouch. Torturous. (1)

dcollins117 (1267462) | more than 5 years ago | (#28984483)

Peoples' well-being comes before animals'.

I wonder if you would still have that opinion if you were reincarnated as a lab monkey.

Re:Ouch. Torturous. (1)

superwiz (655733) | more than 5 years ago | (#28984591)

I wonder if you would still have that opinion if you were reincarnated as a lab monkey.

I don't wonder that. I am also going to continue not wondering that. I'll take my chances. But I do appreciate the concern. Really... I really do.

Re:Ouch. Torturous. (0)

Anonymous Coward | more than 5 years ago | (#28984801)

I wonder what your opinion would be if you were reincarnated as an anti-monkey! (Suffering pain when it experiences pleasure, and vice versa)

STD detection neuron pathway (2, Funny)

syousef (465911) | more than 5 years ago | (#28982795)

I propose the name "STD detection neuron pathway". Now hand me that cream and leave me alone.

Re:STD detection neuron pathway (0)

Anonymous Coward | more than 5 years ago | (#28983159)

You are itching for that cream aren't you ? ;)

Itch (5, Insightful)

Tofof (199751) | more than 5 years ago | (#28982809)

Great. After reading that, now I'm keenly aware of itching sensations all over my body - not unlike watching someone yawn.

Re:Itch (4, Funny)

masshuu (1260516) | more than 5 years ago | (#28982901)

i was gona mod you Informative, but i decided that telling people to not read his comment is more important, otherwise it will drive you insane.

OMG THE ICHING

Re:Itch (-1, Offtopic)

Anonymous Coward | more than 5 years ago | (#28983033)

ha ha you conformist

Re:Itch (3, Insightful)

6Yankee (597075) | more than 5 years ago | (#28983009)

I was already itching - stupid eczema.

Now hopefully these people will hurry up and find a way to turn this off. I can't wait.

Re:Itch (0)

Anonymous Coward | more than 5 years ago | (#28983175)

This is a documented effect. In fact, I've heard storied about how it's hilarious to go to a medical or scientific conference about itching—perhaps one concerning the subject of this very thread—and watch the audience fidget and scratch through the whole thing.

I had to scratch about six times just while typing this post.

Re:Itch (0)

Anonymous Coward | more than 5 years ago | (#28983591)

you are now breathing manually

Interesting from an evolution POV (3, Interesting)

WindBourne (631190) | more than 5 years ago | (#28982813)

I have always thought that Evolution prefers the minimal amounts needed for life (greater complexity is difficult to maintain UNLESS for a reason). As such, it would be easier on life if the same neuron conveys pain and itch. Yet, Evolution chose to do something different.

I wonder what was the stimuli for that?

Re:Interesting from an evolution POV (3, Insightful)

ZackSchil (560462) | more than 5 years ago | (#28982843)

Removal of parasites, probably.

Re:Interesting from an evolution POV (2, Interesting)

wizardforce (1005805) | more than 5 years ago | (#28982865)

the two sensations could have evolved at differing times. pain would be most useful to prevent damage and the abiltiy to sense an itch is useful for correcting problems such as dry skin, certain chemical exposure etc. pain is associated with injury perhaps cells that sense an itch don't work the same way [no one has lopped off an arm and felt an itch for it after all...]

Re:Interesting from an evolution POV (4, Interesting)

ZackSchil (560462) | more than 5 years ago | (#28982909)

[no one has lopped off an arm and felt an itch for it after all...]

Clearly you've never lost a limb. Phantom limb sensations cover pressure, pain, temperature, and irritation. You definitely can feel an itch on an arm or leg that has been lopped off.

Re:Interesting from an evolution POV (1)

wizardforce (1005805) | more than 5 years ago | (#28982969)

if someone hacks off an arm they are not going to experience anything other than pain first.

Re:Interesting from an evolution POV (4, Informative)

WindBourne (631190) | more than 5 years ago | (#28983279)

Actually, I used to be an EMT back in the 80's. I can tell you that it was easier to deal with ppl that lost fingers or limbs because they RARELY felt it. Likewise, the guy who had been in a gasoline explosion (but his pain was to come; horrible injury to have). The reason is that their body regularly shut down in terms of pain. OTH, a compound fracture of the femur was wicked painful. The gal was screaming, but did not notice the bit that we drilled into her knee. The reason is that all the various muscles around the femur had contracted and the muscles were cramping. Severe pain, but not enough for her body to shut it down. Likewise, a nail had been pulled off and in another case, a piece of wood had gone under a nail (accident), etc. In each case, the pain was enormous, but not enough to shut them down.

Re:Interesting from an evolution POV (1)

eric-x (1348097) | more than 5 years ago | (#28984071)

awesome stories
more please!!

Re:Interesting from an evolution POV (1)

budgenator (254554) | more than 5 years ago | (#28985113)

When the thought "Wow I'm not screaming like a school girl" runs through your mind, you know your really fucked up.

Re:Interesting from an evolution POV (1)

masshuu (1260516) | more than 5 years ago | (#28983071)

Let me word the orignal quote better: "If i stab you in the face with a scalpel, your first sensation and thought is not going to be "Hmm this itches", its going to be more along the lines of "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA HHHHHHHHHHHHHHHHHHHHHHHHHHHH FUUUUUUUUUUUUUCKKKKKKKKKKKKKKKKKKKKKKKKKKKAHHHHHHHHHHHHHHHHHHH"

Re:Interesting from an evolution POV (1)

mcgrew (92797) | more than 5 years ago | (#28985077)

It doesn't even have to be lopped off. A friend of mine lost all use of one of his arms in a motorcycle wreck, and even though the limb is still there but the nerves were severed, he still feels pain. The doctors can't do anything about it.

Re:Interesting from an evolution POV (0)

Anonymous Coward | more than 5 years ago | (#28983003)

Evolution prefers nothing, whatever puts the survival chances up is more likely to survive and more likely to reproduce. There are many reasons I can think of for itching to be separate. For one, it means something completely different.

Re:Interesting from an evolution POV (1)

JSBiff (87824) | more than 5 years ago | (#28983105)

It has often occurred to me that, from an evolutionary standpoint, a great many things that aren't distinctly *negative* (that is, they don't particularly *negatively* impact survival/reproduction) could, once introduced into the genepool through random mutation, could continue to survive for a *very long time* before they *eventually* get removed from the genepool.

Why does *everything* necessarily have to be particularly useful? Mutations are random, so the chances are good that there are random things which are sort of 'neutral' to our survival, which might not get 'selected' out of the population for thousands (millions?) of years. . .

Re:Interesting from an evolution POV (0)

Anonymous Coward | more than 5 years ago | (#28983143)

the chances are good that there are random things which are sort of 'neutral' to our survival, which might not get 'selected' out of the population for thousands (millions?) of years. . .

Like earlobes, the appendix, or nipples on men.

Re:Interesting from an evolution POV (1)

Nathrael (1251426) | more than 5 years ago | (#28983543)

The appendix actually has it's use - it's a "reservoir" for various bacteria. And earlobes exist to warm the ear and maintain balance, I think.

Re:Interesting from an evolution POV (1)

armareum (925270) | more than 5 years ago | (#28983897)

And earlobes exist to ... maintain balance

lol

Re:Interesting from an evolution POV (2, Interesting)

caerwyn (38056) | more than 5 years ago | (#28983241)

You're completely right.

Evolution doesn't really incentivize anything. It provides disincentives for exactly one thing: structures and behaviors that result in a higher likelihood of death before reproduction.

Evolution doesn't give a shit what your quality of life is like- unless it prevents you from reproducing. It doesn't give a shit what you do- after you've produce offspring. This is why male and female end-of-fertility times are correlated, and why that's also highly correlated with degradation of health. We haven't evolved to be immortal- we've evolved to a), create offspring and b) survive long enough to teach them. The same holds true for other species.

There are quite a number of mutations that do not affect our reproductive ability. The fact that evolution doesn't prefer one over the other is not only a good thing- it's an essential thing; that genetic variability is what improves our odds of responding effectively to new and dangerous conditions. Neutral mutations are *very* common- and not only that, they're *essential*.

Re:Interesting from an evolution POV (1)

Mr2001 (90979) | more than 5 years ago | (#28983565)

Evolution doesn't really incentivize anything. It provides disincentives for exactly one thing: structures and behaviors that result in a higher likelihood of death before reproduction.

Don't forget number of offspring. A mutation that limited each parent to producing only one child in their lifetime would wipe itself out pretty quickly.

Re:Interesting from an evolution POV (0)

Anonymous Coward | more than 5 years ago | (#28984957)

>> It has often occurred to me that, from an evolutionary standpoint, a great many things that aren't distinctly *negative* (that is, they don't particularly *negatively* impact survival/reproduction) could, once introduced into the genepool through random mutation, could continue to survive for a *very long time* before they *eventually* get removed from the genepool.

one might call this "scaffolding"

Re:Interesting from an evolution POV (1)

WindBourne (631190) | more than 5 years ago | (#28983359)

Evolution prefers nothing, whatever puts the survival chances up is more likely to survive and more likely to reproduce.
Evolution prefers simplicity for EXACTLY that reason. In general, a simpler system will have a better chance of survival and reproduction. Otherwise, more energy going into survival means that it takes the creature longer periods of time before reproduction, which increases the odds of death. OTH, some amount of systems will move towards complexities.

BTW, if you think that complex systems are preferred, then humans and other creatures such as Great Apes, Whales, elephants, pigs, etc should occupy the majority of living space. All of animals do not even come close to that. The fact that prokaryotes (as simple as it gets WRT to living life) are the largest mass of all should speak volumes about evolution. SO, yes, it does strike me that Evolution DOES prefer.

Re:Interesting from an evolution POV (3, Insightful)

Renraku (518261) | more than 5 years ago | (#28983083)

The reason for pain is to make you escape something.

Such as burning yourself on a stove, getting stabbed, bitten, stung, etc. You don't want these things to happen. Pain is strongly connected with negative in most minds. At least, most pain..

The reason for itching is to call your attention to something.

It's kind of the difference between a critical error and an error. One's a dire warning, and the other one is just an exclamation. It would be very fucking useful to distinguish between the two. One, so that you don't freak out every time you walk through some grasses that tickle your legs. Two, so you don't beat your bed-mate to death when they rub up against you. Three, so you don't let bugs chew on you or flip out every time one does.

I'll bet the 'itching' pathways have other uses as well. Perhaps the tickling response is there?

Re:Interesting from an evolution POV (3, Interesting)

ShakaUVM (157947) | more than 5 years ago | (#28983327)

>>I'll bet the 'itching' pathways have other uses as well. Perhaps the tickling response is there?

Tickling, I believe, is linked with touch. Your brain suppresses/mutes touches done to yourself, which is why most people can't tickle themselves. How does the brain tell? If your motion and the sensation come within a threshold of each other, it mutes the sensation. I think there's something like a 45ms threshold involved - when people moved a machine that then moved a tickling finger, if they added a delay of more than 45ms to it, suddenly people could tickle themselves.

There's a lot of interesting hacks inside the human brain.

Re:Interesting from an evolution POV (0)

Anonymous Coward | more than 5 years ago | (#28983147)

I'm itching to find out too.

Oh crap..

Re:Interesting from an evolution POV (1)

bronney (638318) | more than 5 years ago | (#28983375)

You don't touch yourself much do you?? Sexual stimuli is very close to itching. Try it, you might like it.

Re:Interesting from an evolution POV (2, Insightful)

reverseengineer (580922) | more than 5 years ago | (#28983397)

Actually, this is possibly an excellent example of evolution minimizing complexity through the tactic of re-purposing the same system to be used in different ways in different parts of an organism. As the article notes, the neurons that may be specific to itchiness have a cell surface protein called gastrin-releasing peptide receptor. Gastrin, as the name might suggest, also plays a role in the gastrointestinal system, where it is involved in signaling the release of hydrochloric acid. What do your digestive juices have to do with itchy skin? Notably, gastrin does not work directly to release stomach acid, but rather it binds to what are called ECL cells, which secrete histamine, which then stimulate the parietal cells of the stomach to release acid. Histamine is a versatile molecule that is particularly useful for organizing inflammatory responses, though these responses aren't always welcome. That's why you might take diphenhydramine for allergies and ranitidine for heartburn- both are antihistamines, though for different histamine receptors.

Thus, strangely enough, skin itches share many of the same signaling pathways as digestion. The cell types involved (epithelial tissue) are similar though, so during the evolutionary development of skin, cells would already have inherited a sensitive network of cell surface receptors and signal transduction pathways. Why not find a way to put them to good use?

Re:Interesting from an evolution POV (1)

Dahamma (304068) | more than 5 years ago | (#28983605)

I think you are anthropomorphizing a very broad theory/process waaay too much...

Evolution is basically a series of random changes that results in a higher overall rate of survival. There is really nothing logical or simplifying about it - for example, the vast majority of a human brain, or even the human DNA sequence, is unused. Could be "obsolete" structures, or just random changes/development that never served a purpose but also never had any negative consequences.

If someone were able to design a human brain from scratch, I'm sure it could be 10x as efficient as the one we have.

Re:Interesting from an evolution POV (1)

WindBourne (631190) | more than 5 years ago | (#28983731)

Back in 79/80, when I was in my Genetics class, I had the weird idea as applied to cells. In particular, prof said that DNA was mostly empty space and did absolutely nothing. In addition, it was well known at that time that DNA and RNA only served as mapping and they had absolutely no other function. I told the prof that that kind of logic made zero sense. My rational was that cells will go towards the minimal energy usage and maintaining millions and even billions of base pairs is VERY expensive. I suggested in class that these HAD to do more than just sit around and be this way through "random mutation". Prof got mad at me and I lost a grade for that. 2 years later, a prof at CU happened on RNA cleaving itself. He got a Nobel for that.

Now, I say that evolution will prefer simpler and yet, you and others say that it is not the case; that we have loads of left over material in our body. Well, when growing up, an appendix and spleen were taught as being vestigial organs, with little to no use. Things have changed even just a few days ago. Just because WE do not know of a function for cells, tissues, or an organ, does not mean that it is not being used. I am guessing that nearly all tissues/organs have important uses, or they would slowly disappear. Life that has lower energy requirements is far more likely to survive than one that requires loads of them (think of large dinos vs. the small mammals).

Re:Interesting from an evolution POV (1)

mirkob (660121) | more than 5 years ago | (#28983725)

the major problem in your sentences is the word "chose",

evolution is a result of a lot of different events and none of them is sentient nor is the total of them,

so "choosing" an non redundant path isn't something that a "sentient" evolution logically do, it's simply a frequent occurrence because more simple solution to a problem tend to have easier time survive and reproduce.

Re:Interesting from an evolution POV (0)

Anonymous Coward | more than 5 years ago | (#28983863)

According to dict.org

Chose:
To make choice of; to select; to take by way of preference
from two or more objects offered; to elect; as, to choose
the least of two evils.
....

And what is another term for Evolution? Natural something?

The problem is that you are trying to apply a singular definition to a word that has multiple means. NATURE SELECTS (since it is natural selection), which is the same as saying that NATURE CHOOSES. That word does not mean that there was an intelligence behind it (note though, that it also does not preclude it either). In fact, natural SELECTION (or choice) is the very CORE of evolution. It is not random. There are pressures brought to bear on populations that naturally chooses.

But, if you feel better with changing the word to selection, please feel free to do so. It will not matter in this case.

Uh (1, Interesting)

LeadLine (1278328) | more than 5 years ago | (#28982823)

So we know how we could (possibly) get rid of itches, but is there any research showing what purpose itching has?

Re:Uh (4, Informative)

im_thatoneguy (819432) | more than 5 years ago | (#28982833)

I always thought it was obvious: remove epidermal defects.

Dead skin, parasites etc.

Re:Uh (-1, Offtopic)

DNS-and-BIND (461968) | more than 5 years ago | (#28982963)

Well, you'd think these things are obvious. But, lately with the bailout of AIG, the elevation of Goldman-Sachs and the election of Obama, the only thing that's obvious is the people at the top have little or no idea what's going on. Moreover, they just don't care. Thinking like "well, itching obviously helps primates remove skin defects" is right out, along with any other critical thinking...the people at the bottom have all the power, and they just don't realize it...

Best fucking troll ever (0)

Anonymous Coward | more than 5 years ago | (#28983017)

Man, I wish I had your ability to tie the obviousness of itching to fucking Obama being evil. Think they'll name the new Godwin award after your ability here.

Healing wounds? (0)

Anonymous Coward | more than 5 years ago | (#28983401)

ok, so why do healing skin wounds itch?

Re:Healing wounds? (1)

Thiez (1281866) | more than 5 years ago | (#28984395)

To convince you to lick them? Or maybe it doesn't have a purpose and it's merely something that isn't harmful. Interesting question.

Re:Uh (1)

causality (777677) | more than 5 years ago | (#28982847)

So we know how we could (possibly) get rid of itches, but is there any research showing what purpose itching has?

Making you scratch?

Re:Uh (1)

ILuvRamen (1026668) | more than 5 years ago | (#28982867)

evolutionary anti-bug protection, duh. If we feel certain small nerve firings it's usually because of a bug landing on your skin and touching a hair or two so we scratch and the bug flies away. It doesn't come up much indoors these days of course.

Itchy (0)

parallel_prankster (1455313) | more than 5 years ago | (#28982889)

So how many of you starting getting an itch after reading this article?

Re:Itchy (1)

zmollusc (763634) | more than 5 years ago | (#28982973)

Me.
Also during the article. Right buttock.

Re:Itchy (1)

Sulphur (1548251) | more than 5 years ago | (#28983569)

No child left behind program.

Re:Itchy (1)

pryoplasm (809342) | more than 5 years ago | (#28982981)

A minor itch. But it doesn't seem to be nearly as itch inducing as playind drums on Rock Band. For several test subjects and different testing times (my friends and I just messing around),there has yet to be a test where there was no itching involved. I know correlation =/= causation, but the statistics speak for themself....

Important and relevant research (3, Insightful)

rrohbeck (944847) | more than 5 years ago | (#28983099)

Remember, every successful FOSS project started with a developer who had an itch to scratch. Clearly we need more itching.

Obviously... (1)

Moraelin (679338) | more than 5 years ago | (#28984913)

Obviously so did porn. Not sure if "scratch" is the right word there, though ;)

Reason (1)

sonicmerlin (1505111) | more than 5 years ago | (#28983141)

So what would be the evolutionary reason for itchiness? My theory is that it provided a more acute sensation when something small (like a poisonous insect) was moving across one's skin. Or also perhaps an indicator of infection or disease?

Torture (3, Interesting)

mr100percent (57156) | more than 5 years ago | (#28983447)

I hope they don't use this to build the Agony Booth found in Star Trek.

Re:Torture (0)

Anonymous Coward | more than 5 years ago | (#28983743)

I hope they do...

Does this actually change our conception? (0, Troll)

Trepidity (597) | more than 5 years ago | (#28983461)

This may certainly be interesting from a neuroscience point of view, but I would be troubled if anyone's conception of itching really changed because of a discovery about which neural pathways carry the signal. People who believe in a purely physical world governed by physical laws presumably already accept that everything that happens mentally is in some way or another implemented on our wetware. Is this really drawing some veil back: previously we thought itching was a magical sensation that came directly from fairies, but now we know it's "just neurons"? I would also be cautious about any particularly simplistic reductionist view: most of what goes on in the brain is much more complex than pop-science neuroscience discussions like to make out.

I could have told them that after my dentist visit (5, Interesting)

mrjb (547783) | more than 5 years ago | (#28983561)

After a dentist visit with local anesthesia, I got bitten by a mosquito which caused a terrible itch on my cheek- but I couldn't feel my scratching to relief it. NOT FUN.

Re:I could have told them that after my dentist vi (0)

Anonymous Coward | more than 5 years ago | (#28983845)

After a dentist visit with local anesthesia, I got bitten by a mosquito which caused a terrible itch on my cheek- but I couldn't feel my scratching to relief it. NOT FUN.

very interesting, I would mod you up if I could.
I assume that is because pressure sensitive neurons have been knocked out by the anaesthetic.

Stroking vs touch (1)

TeknoHog (164938) | more than 5 years ago | (#28983793)

I recall a documentary where a woman had lost her sense of touch, but she still responded to stroking. The explanation was two different systems of nerves. A particularly interesting bit was that the sense of stroking was much slower, as if the signals only travelled around one meter per second. Given the fine line between stroking and tickling, this seems like the same phenomenon as in the article.

Two Channel Interpretations (2, Interesting)

DynaSoar (714234) | more than 5 years ago | (#28983991)

A nice article and summary. Not entirely new nor inclusive of present theory unfortunately.

Pain is handled by two channels: nocioception, the sensation itself, and the perceptual distress component. This can easily be seen in the actions of the agents affecting each. Sensation is blocked by anesthesia. Interpretation of the pain signal is altered by analgseia -- you may still feel a sensation but you don't care, or at lest you're not so bothered by it. There are different neural pathways and processes to handle these.

It is likely that itching relates to pain in this fashion. The sensation of pressure or stretching of the skin in certain places would be common to all as their are receptors in the skin for these. A parallel pathway governing perceptual interpretation of that sensation, possibly the same one as for pain, would also exist. The resulting interpretation based on personal experience and/or genetically determined wiring would cause different interpretations of the same experience on different individuals, the same individual under different conditions, or (as is common) different locations on the same individual.

a curse you should never wish on your worst enemy: (3, Interesting)

circletimessquare (444983) | more than 5 years ago | (#28984817)

the phantom itch

http://www.newyorker.com/reporting/2008/06/30/080630fa_fact_gawande?currentPage=all [newyorker.com]

same neurological basis as a phantom limb, but far more rare (blessedly so)

it is probably one of the greatest definitions of hell on earth. the itch that never, ever goes away:

M. was willing to consider such possibilities. Her life had been a mess, after all. But the antidepressant medications often prescribed for O.C.D. made no difference. And she didn't actually feel a compulsion to pull out her hair. She simply felt itchy, on the area of her scalp that was left numb from the shingles. Although she could sometimes distract herself from it--by watching television or talking with a friend--the itch did not fluctuate with her mood or level of stress. The only thing that came close to offering relief was to scratch.
"Scratching is one of the sweetest gratifications of nature, and as ready at hand as any," Montaigne wrote. "But repentance follows too annoyingly close at its heels." For M., certainly, it did: the itching was so torturous, and the area so numb, that her scratching began to go through the skin. At a later office visit, her doctor found a silver-dollar-size patch of scalp where skin had been replaced by scab. M. tried bandaging her head, wearing caps to bed. But her fingernails would always find a way to her flesh, especially while she slept.
One morning, after she was awakened by her bedside alarm, she sat up and, she recalled, "this fluid came down my face, this greenish liquid." She pressed a square of gauze to her head and went to see her doctor again. M. showed the doctor the fluid on the dressing. The doctor looked closely at the wound. She shined a light on it and in M.'s eyes. Then she walked out of the room and called an ambulance. Only in the Emergency Department at Massachusetts General Hospital, after the doctors started swarming, and one told her she needed surgery now, did M. learn what had happened. She had scratched through her skull during the night--and all the way into her brain.

...

The second theory seemed less likely. If the nerves to her scalp were dead, how would you explain the relief she got from scratching, or from the local anesthetic? Indeed, how could you explain the itch in the first place? An itch without nerve endings didn't make sense. The neurosurgeons stuck with the first theory; they offered to cut the main sensory nerve to the front of M.'s scalp and abolish the itching permanently. Oaklander, however, thought that the second theory was the right one--that this was a brain problem, not a nerve problem--and that cutting the nerve would do more harm than good. She argued with the neurosurgeons, and she advised M. not to let them do any cutting.
"But I was desperate," M. told me. She let them operate on her, slicing the supraorbital nerve above the right eye. When she woke up, a whole section of her forehead was numb--and the itching was gone. A few weeks later, however, it came back, in an even wider expanse than before. The doctors tried pain medications, more psychiatric medications, more local anesthetic. But the only thing that kept M. from tearing her skin and skull open again, the doctors found, was to put a foam football helmet on her head and bind her wrists to the bedrails at night.
She spent the next two years committed to a locked medical ward in a rehabilitation hospital--because, although she was not mentally ill, she was considered a danger to herself. Eventually, the staff worked out a solution that did not require binding her to the bedrails. Along with the football helmet, she had to wear white mitts that were secured around her wrists by surgical tape. "Every bedtime, it looked like they were dressing me up for Halloween--me and the guy next to me," she told me.
"The guy next to you?" I asked. He had had shingles on his neck, she explained, and also developed a persistent itch. "Every night, they would wrap up his hands and wrap up mine." She spoke more softly now. "But I heard he ended up dying from it, because he scratched into his carotid artery."

Psoriasis (0)

Anonymous Coward | more than 5 years ago | (#28984905)

As someone who's dealt with psoriasis since the age of five I can only hope that they can use this knowledge to find a way to turn the fucking itching OFF. :(

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