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Sunday 10 July 2016

Is a 'Mystery Virus' Causing Former Tennis Starꞌs Bizarre Symptoms?

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Rachael Rettner
Rachael Rettner, Senior Writer
Rachael has been with Live Science since 2010. She has a masters degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a Bachelor of Science in molecular biology and a Master of Science in biology from the University of California, San Diego.

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Is a 'Mystery Virus' Causing Former Tennis Starꞌs Bizarre Symptoms?
Marion Bartoli in 2015
Credit: Jimmie48 Photography/Shutterstock.com

Former professional tennis player Marion Bartoli says that a mysterious virus is causing her to experience bizarre symptoms, but experts say they donꞌt know of any virus that fits the description of her illness.
Yesterday (July 7), Bartoli addressed rumors that she has an eating disorder by saying that she has been diagnosed with a virus that doctors have not been able to identify. The virus has made her sensitive to electrical devices, including her cellphone, and left her unable to eat anything but organic salad, the former Wimbledon champion said, according to The Guardian.
"Iꞌm reduced to eating organic salad leaves with cucumber without the skin, because my body can't even process the skin," Bartoli was quoted as saying. "I canꞌt be on my phone for more than five minutes as my heart starts to pump ... Every time I do something, Iꞌm scared to see the reaction to my body," she said. Bartoli also said she is sensitive to tap water, and must wash herself with mineral water.
There's not one specific virus that I know of thatꞌs known to cause those types of symptoms," said Dr. Amesh Adalja, an infectious-disease specialist and a senior associate at the University of Pittsburgh Medical Center's Center for Health Security, who is not involved with treating Bartoli. [Here's a Giant List of the Strangest Medical Cases We've Covered]
Some viral illnesses are known to cause people to have odd sensations, such as feelings of pain, tingling or numbness, because the virus damages nerves, Adalja said. But the viral illnesses that cause such symptoms, such as shingles and HIV, are often easy to diagnose, Adalja said.
Neuropathy can also have other causes, including a bacterial infection or exposure to certain toxins. For example, exposure to a chemical called ciguatoxin, which is produced by microorganisms and can be present in the fish that consume them, may cause increased sensitivity to hot and cold, Adalja said. People exposed to ciguatoxin, which also causes gastrointestinal problems, can experience symptoms for weeks or months. They may even get better only to have their symptom recur after they eat certain foods, including fish or nuts, or drink alcoholic beverages, according to the Woods Hole Oceanographic Institution.
For some of Bartoli's reported symptoms — including heart palpitations when on her cellphone and an inability to eat anything other than organic salad — a viral cause doesn't seem biologically plausible, Adalja said.
"I donꞌt think I can think of a pathophysiological mechanism" by which a virus could cause the heart to pump faster when on a cellphone, Adalja said. And it's not clear how a virus would distinguish between organic and non-organic food, he said. "Organic is more of a marketing label than any substantial difference in the food," Adalja said.
When people have chronic symptoms after they recover from an infectious disease, they may sometimes attribute their new symptoms to the illness, even if they aren't related. "It becomes hard to untangle what's actually a residual effect [of the illness], and what is something else thatꞌs going on that may not be related to it," Adalja said.
In other cases, doctors simply can't figure out what is going on with a patient, and may attribute the patientꞌs symptoms to a virus, Adalja said.
If a person was ill but no longer has the virus or infectious agent in their body, it can be very difficult to figure out what they were infected with, Adalja said. A doctor might test for the more common viruses but is "left with really no answer," if the tests don't show a cause, he said.
Bartoli said she thinks she became infected with a virus during a trip to India. She says she will start treatment for her condition next week.


Original article on Live Science.

12,000-Year-Old Shaman's Elaborate Funeral Had 6 Stages

Author Bio
Mindy Weisberger
Mindy Weisberger, Senior Writer
Mindy Weisberger is a senior writer for Live Science covering general science topics, especially those relating to brains, bodies, and behaviors in humans and other animals — living and extinct. Mindy studied filmmaking at Columbia University; her videos about dinosaurs, biodiversity, human origins, evolution, and astrophysics appear in the American Museum of Natural History, on YouTube, and in museums and science centers worldwide. Follow Mindy on Twitter.

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12,000-Year-Old Shaman's Elaborate Funeral Had 6 Stages
Bones of a mysterious woman in a burial site were surrounded by tortoise shells and other objects.
Credit: Naftali Hilger
A diminutive woman buried in a cave in Israel 12,000 years ago was likely a person of importance and was interred with great ceremony, including a feast of 86 tortoises, archaeological evidence suggests.
After years of analysis, experts have reconstructed the stages of a funeral ritual performed as the body was laid to rest, piecing together the chain of events with the help of unusual objects that were found at the burial site.
The researchers described a six-step process that acknowledged the respected position that the woman held in life, and hints at the complexity of burial rituals practiced in the region thousands of years in the past. [The Science of Death: 10 Tales from the Crypt & Beyond]
Study lead author Leore Grosman, a professor at the Institute of Archaeology at the Hebrew University of Jerusalem, discovered the grave in 2005, in a cave called Hilazon Tachtit, located in western Galilee in northern Israel.
The cave served as a burial ground for at least 28 people during the latter part of the Natufian period (15,000 – 11,500 B.C.), according to a study Grosman co-authored in 2008, published in the Proceedings of the National Academy of Sciences.

The entrance to the Hilazon Tachtit cave in northern Israel.
The entrance to the Hilazon Tachtit cave in northern Israel.
Credit: Leore Grosman

And one grave stood out, separated from other graves by a stone divider, and with the body and objects around it arranged with particular care and intent.
The skeleton of a woman about 4 feet 9 inches (1.5 meters) tall and about 45 years old had been carefully placed in a grave pit layered with sediment, seashells, tortoise shells, chalk and bony horn cores from gazelles. Arranged around and upon her body were bones representing a number of animals: marten skulls, a wild cow tail, a boar's forearm, a leopard's pelvis, an eagle's wing and a human foot.
In a statement, Grosman described the occupant of the grave as "probably a shaman," based on the variety of animal bones surrounding her, because shamans of the time were believed to commune with animal spirits.
Grosman and study co-author Natalie Munro, a professor in the anthropology department at the University of Connecticut, analyzed the contents of the grave and determined the ritual sequence — six stages — that likely accompanied the woman's burial.
For the first stage — preparing the grave pit — attendants marked a symmetrical oval shape in the bedrock of the cave floor, then broke up the bedrock in large chunks with a type of drill. Next, they covered the floor and walls of the pit with mud, adding layers of limestone and other sediments.
The second and third stages involved lining the pit with limestone blocks and "unique artifacts," such as shells, gazelle horn cores and tortoise carapaces, and then covering the artifacts with a layer of ash and debris from chipped stone tools.
During stage four, the woman's corpse was placed in the pit in a squatting position, with tortoise shells inserted underneath the head and pelvis where they rested against the grave's walls. Animal bones and more tortoise shells were positioned atop and around the body, topped by several limestone blocks.

One of 86 tortoise shells buried with a body that may have belonged to a female shaman.
One of 86 tortoise shells buried with a body that may have belonged to a female shaman.
Credit: Leore Grosman 

Dozens of tortoise shells included in this layer represent animals that were eaten during a ritual meal, during which the authors estimated that funeral attendants consumed about 55 pounds (25 kilograms) of meat.
For stage five, attendants filled the grave with garbage from the funeral feast, according to the researchers. And finally, for stage six, a large triangular block of limestone was positioned at the top of the grave.
"The significant preplanning implies that there was a defined 'to do' list, and a working plan of ritual actions and their order," Grosman said in a statement.
According to the authors, the Natufian period is recognized as a time when human burials began emerging as an important cultural practicewithin the community. Evidence from this study suggests that rituals were carefully planned and highly organized, hinting at the complexity of ancient roles and societies.
The findings were published online April 26 in the journal Current Anthropology.
Original article on Live Science.

99-Million-Year-Old Spider Mummy Sported Horned Fangs

Author Bio
Laura Geggel
Laura Geggel, Senior Writer
As a senior writer for Live Science, Laura Geggel covers general science, including the environment and amazing animals. She has written for The New York Times, Scholastic, Popular Science and Spectrum, a site covering autism research. Laura grew up in Seattle and studied English literature and psychology at Washington University in St. Louis before completing her graduate degree in science writing at NYU. When not writing, you'll find Laura playing Ultimate Frisbee. Follow Laura on Google+


99-Million-Year-Old Spider Mummy Sported Horned Fangs
The bizarre armored spider (Electroblemma bifida) from Cretaceous Burmese amber. The adult male pictured above measures 0.06 inches (1.58 millimeters) long. 
Credit: Copyright Paul Selden

About 99 million years ago, two bizarre spiders — each sporting hard, armored plates on their bodies and horns on their fangs — became mummified in sticky tree resin that turned into amber.
They remained there until recently, when scientists discovered the chunk of amber and analyzed the spiders locked inside.
These ancient, extinct spiders are part of a spider family called Tetrablemmidae, a group whose males often have horns on their heads and fangs, said study lead author Paul Selden, a professor of invertebrate paleontology at the University of Kansas.
But the newly identified species has rather "complex" horns that have two prongs at their tips, which is peculiar, even for a Tetrablemmid spider, Selden said. [Weird and Wonderful: 9 Bizarre Spiders]
"The new fossil is an adult male and takes these horns to an extreme," Selden told Live Science in an email. "Nevertheless, the new species can be firmly placed within the modern family and is similar to species living in Southeast Asia and China today."
Both of the amber fossils came from a mine in northern Burma (also known as Myanmar). Selden met with a dealer who was selling the polished specimens in China, and the scientist and his colleagues purchased those that were of scientific interest, he said.
Tetrablemmid spiders usually have six or fewer eyes, but the researchers couldn't find any on the Cretaceous-age specimens, likely because those body parts didn't preserve well, he said. However, the mummies look somewhat similar to the modern Tetrablemmid spiders in the genus Sinamma, which live in southwest China. Sinamma species have eyes on the upper part of the head, so the newfound species likely did too, the researchers said.
"What caught my eye about this spider was the enormous projection on its head, most likely bearing eyes, and the bizarre horns on its fangs," Selden said.
Selden and his colleagues named the new species Electroblemma bifida. The genus name refers to the Greek "elektron," or amber, and "blemma" or appearance, a common suffix used for tetrablemmid spiders. The species name refers to the two-pronged tip at the end of the horns on this spider's fangs, the researchers said.
In general, Tetrablemmid spiders have armor-like hard plates covering their bodies that protect them from predators, such as spider-hunting wasps, Selden said. These spiders are usually tiny, only about a quarter inch (0.6 centimeters) long. The mummified specimens are slightly smaller, with one measuring 0.06 inches (1.58 millimeters) long.
Tetrablemmid's ancestors are known from islands in the Indian ocean, and it's unclear how Tetrablemmid spiders spread to Southeast Asia during prehistoric times, but Selden and his colleagues have an idea. Burmese amber occurs on a geological plate called the West Burma block, which was attached to Australia about 400 million years ago, he said. [Photos: Mummified Bird Wings Preserved in Amber]
"That was before there were spiders known on planet Earth," Selden said. "Over the ensuing millennia, this little plate drifted across to join up with the continent we now call Eurasia, and it reached there sometime in the Jurassic period."
During that period, these Tetrablemmids somehow moved onto the newly docked block in southeast Eurasia, and diversified along with other critters, many of which are also mummified in Burmese amber, Selden said.
The study will be published in the November 2016 issue of the journal Cretaceous Research.
Original article on Live Science.

Where Did Earth's Water Come From?

Author Bio
Jesse Emspak
Jesse Emspak, Live Science Contributor
Jesse Emspak is a contributing writer for Live Science, Space.com and Toms Guide. He focuses on physics, human health and general science. Jesse has a Master of Arts from the University of California, Berkeley School of Journalism, and a Bachelor of Arts from the University of Rochester. Jesse spent years covering finance and cut his teeth at local newspapers, working local politics and police beats. Jesse likes to stay active and holds a third degree black belt in Karate, which just means he now knows how much he has to learn.

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Where Did Earth's Water Come From?
Earth is quite a watery place. Here, a stunning view of our blue planet captured by NOAA's GOES-East satellite on April 22, 2014.
Credit: NASA/NOAA/GOES Project

Look at Earth compared to other rocky planets in the neighborhood, and the first thing that would likely jump out is that there's A LOT of water. So how did 70 percent of our planet's surface become covered in this essential life ingredient?
That question is the subject of lively scientific debate, it turns out.
There are two prevailing theories: One is that the Earth held onto some water when it formed, as there would have been ice in the nebula of gas and dust (called the proto-solar nebula) that eventually formed the sun and the planets about 4.5 billion years ago. Some of that water has remained with the Earth, and might be recycled through the planet's mantle layer, according to one theory.
The second theory holds that the Earth, VenusMars and Mercury would have been close enough to that proto-solar nebula that most of their water would have been vaporized by heat; these planets would have formed with little water in their rocks. In Earth's case, even more water would have been vaporized when the collision that formed the moon happened. In this scenario, instead of being home-grown, the oceans would have been delivered by ice-rich asteroids, called carbonaceous chondrites.



More and more research suggests that asteroids delivered at least some of Earth's water.
More and more research suggests that asteroids delivered at least some of Earth's water. 
Credit: ESA/P. Carril 

Scientists can track the origin of Earth's water by looking at the ratio of two isotopes of hydrogen, or versions of hydrogen with a different number of neutrons, that occur in nature. One is ordinary hydrogen, which has just a proton in the nucleus, and the other is deuterium, also known as "heavy" hydrogen, which has a proton and a neutron. 
The ratio of deuterium to hydrogen in Earth's oceans seems to closely match that of asteroids, which are often rich in water and other elements such as carbon and nitrogen, rather than comets. (Whereas asteroids are small rocky bodies that orbit the sun, comets are icy bodies sometimes called dirty snowballs that release gas and dust and are thought to be leftovers from the solar system's formation.)



Meteorite EET 83309 contains tiny fragments of opal, a material that requires water to form. In this backscattered electron image, a narrow opal rim surrounds a bright metallic mineral inclusion.
Meteorite EET 83309 contains tiny fragments of opal, a material that requires water to form. In this backscattered electron image, a narrow opal rim surrounds a bright metallic mineral inclusion.
Credit: H. Downes

Scientists have also discovered opals in meteoritesthat originated among asteroids (they are likely pieces knocked off of asteroids). Since opals need water to form, this finding was another indication of water coming from space rocks. These two pieces of evidence would favor an asteroid origin. In addition, deuterium tends to gather farther out in the solar system than hydrogen does, so water formed in the outer regions of the system would tend to be deuterium-rich.
And on top of that, the rocky inner planets hold relatively little water (relative to their masses) compared with the icy moons of Jupiter, Saturn, Uranus and Neptune, and even the gas giants themselves. That would support the idea that in the inner system, the water evaporated, while in the outer system, it didn't. If water evaporated on Earth it would have to be replaced from somewhere else, and water-rich asteroids are abundant in the outer reaches of the system.
More supporting evidence comes from NASA's DAWN spacecraft, launched in 2007, which found evidence of water on Ceres and Vesta, the two largest objects in the main asteroid belt located between Mars and Jupiter.



This false-color image of Ceres from NASA’s Dawn probe highlights the differences in surface materials across the dwarf planet.
This false-color image of Ceres from NASA’s Dawn probe highlights the differences in surface materials across the dwarf planet.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA 

A slam dunk for asteroids? Not so fast. For this scenario to work, the isotope ratio had to have stayed the same in the oceans over the last few billion years.
But what if it didn't? 
Lydia Hallis, a planetary scientist with the University of Glasgow in the United Kingdom, thinks that the hydrogen present on the early Earth had much less deuterium in it than it does now. The ratio changed because in the early history of the Earth the radiation from the sun heated up both hydrogen and deuterium. Hydrogen, being lighter, was more likely to fly off into outer space, leaving more deuterium behind.
Also, in the last several years, newer models seem to show that the Earth retained a lot of water as it formed, and that the oceans might have been present for much longer than anyone thought.
Hallis and her colleagues looked at hydrogen isotope ratios in ancient Canadian rocks, some of the oldest rocks on Earth. The isotope ratios looked a lot less like asteroids and a lot more like the water one would expect from the early solar nebula in the region — the rocks had more ordinary hydrogen and less deuterium. But the current ocean ratio looks like asteroids. That would seem to indicate something changed in the last few billion years. The research was published in Science in 2015. 
If the Earth's oceans were formed from water on our own planet, rather than asteroids, that would solve a couple of problems for planetary scientists. One is why Earth seems to have so much water in the first place. Another is why life, which as far as anyone knows requires water, seems to have appeared so quickly once the Earth had a solid surface.
Besides the work of Hallis, other scientists have studied ways water could be recycled from Earth's interior. In 2014, Wendy Panero, an associate professor of earth sciences at Ohio State, and doctoral student Jeff Pigott proposed the theory that Earth was formed with entire oceans of water in its interior. Via plate tectonics, that water has been supplying the oceans. They studied garnet, and found it could work with another mineral, called ringwoodite, to deliver water to the Earth's interior – water that would later come up as the mantle material circulated.
Complicating the picture, neither of these hypotheses is mutually exclusive. Asteroids could deliver water while some could come from the Earth's interior. The question is how much each would deliver — and how to find that out.
So this mystery will remain one, at least for a little while longer.
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Why People Consider 'Normal' to Be 'Good'

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By  | 

Why People Consider 'Normal' to Be 'Good'
people often mistake normality as a criterion for morality, scientists say.
Credit: hidesy / Shutterstock.com
The Binewskis are no ordinary family. Arty has flippers instead of limbs; Iphy and Elly are Siamese twins; Chick has telekinetic powers. These traveling circus performers see their differences as talents, but others consider them freaks with “no values or morals.” However, appearances can be misleading: The true villain of the Binewski tale is arguably Miss Lick, a physically “normal” woman with nefarious intentions.
Much like the fictional characters of Katherine Dunn’s “Geek Love,” everyday people often mistake normality as a criterion for morality. Yet, freaks and norms alike may find themselves anywhere along the good/bad continuum. Still, people use what’s typical as a benchmark for what’s good, and are often averse to behavior that goes against the norm. Why?
In a series of studies, psychologist Andrei Cimpian and I investigated why people use the status quo as a moral codebook – a way to decipher right from wrong and good from bad. Our inspiration for the project was philosopher David Hume, who pointed out that people tend to allow the status quo (“what is”) to guide their moral judgments (“what ought to be”). Just because a behavior or practice exists, that doesn’t mean it’s good – but that’s exactly how people often reason. Slavery and child labor, for example, were and still are popular in some parts of the world, but their existence doesn’t make them right or OK. We wanted to understand the psychology behind the reasoning that prevalence is grounds for moral goodness.
To examine the roots of such “is-to-ought inferences,” we turned to a basic element of human cognition: how we explain what we observe in our environments. From a young age, we try to understand what’s going on around us, and we often do so by explaining. Explanations are at the root of many deeply held beliefs. Might people’s explanations also influence their beliefs about right and wrong?
When coming up with explanations to make sense of the world around us, the need for efficiency often trumps the need for accuracy. (People don’t have the time and cognitive resources to strive for perfection with every explanation, decision or judgment.) Under most circumstances, they just need to quickly get the job done, cognitively speaking. When faced with an unknown, an efficient detective takes shortcuts, relying on simple information that comes to mind readily.
More often than not, what comes to mind first tends to involve “inherent” or “intrinsic” characteristics of whatever is being explained.
For example, if I’m explaining why men and women have separate public bathrooms, I might first say it’s because of the anatomical differences between the sexes. The tendency to explain using such inherent features often leads people to ignore other relevant information about the circumstances or the history of the phenomenon being explained. In reality, public bathrooms in the United States became segregated by gender only in the late 19th century – not as an acknowledgment of the different anatomies of men and women, but rather as part of a series of political changes that reinforced the notion that women’s place in society was different from that of men.
We wanted to know if the tendency to explain things based on their inherent qualities also leads people to value what’s typical.
To test whether people’s preference for inherent explanations is related to their is-to-ought inferences, we first asked our participants to rate their agreement with a number of inherent explanations: For example, girls wear pink because it’s a dainty, flower-like color. This served as a measure of participants’ preference for inherent explanations.
In another part of the study, we asked people to read mock press releases that reported statistics about common behaviors. For example, one stated that 90 percent of Americans drink coffee. Participants were then asked whether these behaviors were “good” and “as it should be.” That gave us a measure of participants’ is-to-ought inferences.
These two measures were closely related: People who favored inherent explanations were also more likely to think that typical behaviors are what people should do.
We tend to see the commonplace as good and how things should be. For example, if I think public bathrooms are segregated by gender because of the inherent differences between men and women, I might also think this practice is appropriate and good (a value judgment).
This relationship was present even when we statistically adjusted for a number of other cognitive or ideological tendencies. We wondered, for example, if the link between explanation and moral judgment might be accounted for by participants’ political views. Maybe people who are more politically conservative view the status quo as good, and also lean toward inherence when explaining? This alternative was not supported by the data, however, and neither were any of the others we considered. Rather, our results revealed a unique link between explanation biases and moral judgment.
We also wanted to find out at what age the link between explanation and moral judgment develops. The earlier in life this link is present, the greater its influence may be on the development of children’s ideas about right and wrong.
From prior work, we knew that the bias to explain via inherent information is present even in four-year-old children. Preschoolers are more likely to think that brides wear white at weddings, for example, because of something about the color white itself, and not because of a fashion trend people just decided to follow.
Does this bias also affect children’s moral judgment?
Indeed, as we found with adults, 4- to 7-year-old children who favored inherent explanations were also more likely to see typical behaviors (such as boys wearing pants and girls wearing dresses) as being good and right.
If what we’re claiming is correct, changes in how people explain what’s typical should change how they think about right and wrong. When people have access to more information about how the world works, it might be easier for them to imagine the world being different. In particular, if people are given explanations they may not have considered initially, they may be less likely to assume “what is” equals “what ought to be.”
Consistent with this possibility, we found that by subtly manipulating people’s explanations, we could change their tendency to make is-to-ought inferences. When we put adults in what we call a more “extrinsic” (and less inherent) mindset, they were less likely to think that common behaviors are necessarily what people should do. For instance, even children were less likely to view the status quo (brides wear white) as good and right when they were provided with an external explanation for it (a popular queen long ago wore white at her wedding, and then everyone started copying her).
Our studies reveal some of the psychology behind the human tendency to make the leap from “is” to “ought.” Although there are probably manyfactors that feed into this tendency, one of its sources seems to be a simple quirk of our cognitive systems: the early emerging bias toward inherence that’s present in our everyday explanations.
This quirk may be one reason why people – even very young ones – have such harsh reactions to behaviors that go against the norm. For matters pertaining to social and political reform, it may be useful to consider how such cognitive factors lead people to resist social change.
Christina Tworek, Ph.D. Student in Developmental Psychology, University of Illinois at Urbana-Champaign


This article was originally published on The Conversation. Read the original article.

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Seeing Green: Pot Changes Brain's Response to Money

Author Bio
Agata Blaszczak-Boxe
Agata Blaszczak-Boxe, Contributing Writer
Agata Blaszczak-Boxe is a contributing writer for Live Science. She covers health, psychology and paleontology, as well as other science topics. Agata has a Master of Arts degree from the City University of New York Graduate School of Journalism. When she is not writing, she can be found reading food blogs, lifting weights or playing with her two attention-hungry cats. Follow Agata on Twitter.

Seeing Green: Pot Changes Brain's Response to Money
Credit: agsandrew | Shutterstock.com
Smoking marijuana may change the way people's brains respond to certain rewards, such as the prospect of winning some money, according to a new study.
In the study, participants played a game in which they could win a small amount of money. The researchers found that the brains of people who smoked marijuana did not respond to the idea of winning the money as strongly as did the brains of people who did not use the drug.
The results suggest that for people who smoke pot, "there is not as much pleasure that is being received from something that would naturally give somebody pleasure," study author Mary Heitzeg, an assistant professor of psychiatry at the University of Michigan Medical School, told Live Science. [7 Ways Marijuana May Affect the Brain]
In the study, researchers looked at 108 people in their early 20s. The researchers scanned the participants' brains three times over the course of the four-year study. During the brain scans, the people played a game in which they were asked to click a button whenever they saw a target appear on a screen in front of them. Before each round, the researchers told the people that, depending on how they performed in the game, they might win 20 cents, win $5, lose that same amount of money, or have no reward or loss.
The scientists said they wanted to see what happened in the area of the brain called the nucleus accumbens, which is responsible for responding to rewards, at the moment the participants knew they might win some money. In that moment, when a person is anticipating a reward, the cells of that part of the brain are normally activated, pumping out a "pleasure chemical" called dopamine. The stronger the brain response, the more pleasure a person feels.
The people in the study who more frequently used marijuana showed weaker brain responses over time than those who used the drug less frequently or did not use marijuana at all, according to the findings, published today (July 6) in the journal JAMA Psychiatry. The more marijuana a person smoked, the weaker their brain response, the researchers found.
The new study adds to other research that has suggested that marijuana use is linked to problems with emotional functioning and academic achievement, and even changes in brain structure, the researchers said.
The new research also suggests that the earlier in life a person tries marijuana, the faster that individual may transition to becoming dependent on the drug or other substances, the researchers said.
"Some people may believe that marijuana is not addictive or that it's 'better' than other drugs that can cause dependence," Heitzeg said. But the new study shows that marijuana's effects on the brain may make it more difficult for people to stop using the substance, she said.
"It changes your brain in a way that may change your behavior, and where you get your sense of reward from," Heitzeg added.
The new study shows an association between marijuana use and changes in the brain's reward system, but it does not prove that marijuana use causes the changes, Francesca Filbey, an associate professor of behavioral and brain science at the University of Texas at Dallas, who was not involved in the study, wrote in a related editorial published in the same journal. More research is needed to determine whether the changes are the cause or the consequence of marijuana use, she said.
It also possible that certain underlying genetic factors make people more likely to start using marijuana and that the same factors make them more susceptible to certain brain changes, Filbey wrote.


Originally published on Live Science.

Advantages and Disadvantages of Fasting for Runners

Author BY   ANDREA CESPEDES  Food is fuel, especially for serious runners who need a lot of energy. It may seem counterintuiti...