New research shows that acne increases risk of depression by more than 60%

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ndividuals with acne have a significantly increased risk for depression within the first 5 years after receiving an acne diagnosis, according to a recent study.

For their study, Dr Isabelle Vallerand, of the University of Calgary in Canada, and colleagues obtained and evaluated patient data from the 1986-2012 Health Improvement Network (THIN) in the United Kingdom.

Results of the analysis revealed that individuals with acne had a 63% higher risk for depression within 1 year after diagnosis compared with individuals without acne, thus indicating the importance of evaluating patients with acne for symptoms of depression.

“This study highlights an important link between skin disease and mental illness,” Dr Vallerand said in a press release.

“Given the risk of depression was highest in the period right after the first time a patient presented to a physician for acne concerns, it shows just how impactful our skin can be towards our overall mental health.”

—Christina Vogt

Reference:

Vallerand IA, Lewinson RT, Parsons LM, et al. Risk of depression among patients with acne in the U.K.: a population-based cohort study [published online February 7, 2018]. Brit J Dermatol. doi:10.1111/bjd.16099.

https://www.consultant360.com/exclusives/acne-inflates-depression-risk-63

Self-cloning crayfish may be unstoppable

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by NOEL KIRKPATRICK

nvasions are usually difficult to miss, whether it’s a military invasion conducted by countries or political factions, or the fictional invasion of alien lifeforms and their very big ships.

However, one invasion began so quietly that we’re not even sure where, or how, it started. All we do know for sure is that the invaders are all over Europe and Madagascar, and that they have toeholds in other continents, including North America. Or maybe “clawholds” is a better phrase since the invaders are mutant crayfish that can clone themselves.

Yes, that’s right. Self-cloning crayfish called marbled crayfish (Procambarus virginalis) have invaded the planet, and it may be not be possible to stop them.

Marbled crayfish didn’t even exist until at least 1995. The story goes that it scientists only became aware of it because of a German aquarium owner who had gotten a bag of “Texan crayfish” from an American pet trader. Not long after the crayfish reached adulthood, the owner suddenly had a tank full of the creatures. Indeed, a single marbled crayfish can produce hundreds of eggs at a time, and all without needing to mate.

Scientists officially described the crayfish in 2003, confirming the reports of a crayfish capable of unisexual reproduction (all marbled crayfish are female), or parthenogenesis. These researchers did try to warn us about the havoc the crayfish could cause, writing that the species poses a “potential ecological threat” that could “outcompete native forms should even a single specimen be released into European lakes and rivers.”

Now, thanks to unwitting pet owners who dumped them into nearby lakes, feral populations of the marbled crayfish have been found in in a number of countries, including Croatia, the Czech Republic, Hungary, Japan, Sweden and Ukraine. In Madagascar, the marbled crayfish is threatening the existence of seven other crayfish species because its population grows so quickly and it will eat just about anything. In the European Union, the species, which is also called marmorkrebs, is banned; it’s illegal to own, distribute, sell or release the marbled crayfish into the wild.

A team of researchers decided to get to the bottom of the marbled crayfish’s origins and began work on sequencing its genome in 2013. This was no easy task since no one had sequenced the genome of a crayfish before, or even a relative of the crayfish. Once they sequenced it, however, they sequenced another 15 specimens’ genomes to suss out how this invasive clone army got started.

The study of the marbled crayfish’s genome was published in Nature Ecology and Evolution.

Marbled crayfish likely got their start when two slough crayfish, a species found in Florida, mated. One of those slough crayfish had a mutation in a sex cell — researchers couldn’t determine if it was an egg or sperm cell — that carried two sets of chromosomes instead of just one. Despite this mutation, the sex cells fused and the result was a female crayfish with three sets of chromosomes instead of the usual two. Also unexpectedly, the female offspring didn’t have any deformities as a result of those extra chromosomes.

That female was able to induce her own eggs and essentially clone herself, creating hundreds of offspring. The genetic similarities were constant across specimens, regardless of where they were collected. Only a few letters in crayfish’s DNA sequence were different.

As to how the crayfish is able to survive in such different waters, its extra chromosome may provide enough genetic material for it to adapt. And it may need that chromosome for other aspects of survival, too. Sexual reproduction creates different combinations of genes that in turn can increase the odds of developing a defense to pathogens. Should one pathogen develop a way to kill a single clone, the crayfish’s lack of genetic diversity could be its downfall.

Until then, scientists are intrigued to observe how well the crayfish can thrive, and for how long.

“Maybe they just survive for 100,000 years,” Frank Lyko, and lead author on the gene study suggested to The New York Times. “That would be a long time for me personally, but in evolution it would just be a blip on the radar.”

https://www.mnn.com/earth-matters/animals/stories/marbled-crayfish-self-cloning-invasion

Thanks to Kebmodee for bringing this to the It’s Interesting community.

How Cheetahs Keep Their Heads Still While Sprinting

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By Elaina Zachos

Cheetahs are synonymous with speed. But past the big cat’s slender build and lean muscles, there’s something inside that aids this animal’s need for speed.

A new report, published February 2 in Scientific Reports, shows that certain parts of the cheetah’s inner ear help to make it a better hunter. The study marks the first time researchers have analyzed the big cats’ inner ear.

ALL EARS
If you watch a cheetah sprinting in slow motion, you can see that they tend to keep their heads stable and their eyes fixed on prey even while in motion. To learn how the animal’s bone structure helps with this, lead author Camille Grohé turned to the animals’ inner ear.

The inner ear is crucial for maintaining balance and a steady head posture. It consists of three semicircular canals containing fluid and sensory hair cells that pick up motion in the head. Since each canal is angled differently, they’re each sensitive to different movements: one targets up-and-down motion, one side-to-side, and one tilts from one side to the other.

Using high-resolution imaging, Grohé and the team scanned 21 felid skulls. While some skulls were of other big cats, seven belonged to modern cheetahs. The researchers also imaged the skull of an extinct giant cheetah to see how the inner ear might have evolved.

The inner ears of cheetahs are like that of no other modern felids, the study found. Large vestibular systems—which help with balance—took up more of the inner ear of the cheetah than of any other big cat. Cheetahs also had longer semicircular ear canals, which help with head movement and eye direction.

“This distinctive inner ear anatomy reflects enhanced sensitivity and more rapid response to head motions,” co-author John Flynn says in a press release.

These highly-tuned traits were not seen in the extinct cheetah species, which shows these developments in the cheetah’s inner ear happened relatively recently.

“The living cheetah’s ancestors have evolved slender bones that would allow them to run very fast and then an inner ear ultra-sensitive to head movements to hold their head still, enabling them to run even faster,” Grohé adds.

BUILT FOR SPEED
As the fastest land animal, lightweight cheetahs are built for sprinting. Their spines are long and flexible, which allows them to launch from 0 to 60 miles per hour in just three seconds. While their strong, lean muscles help propel them forward, their large nasal cavities help them gulp in air to recover after a chase.

https://news.nationalgeographic.com/2018/02/cheetah-inner-ear-speed-hunting-spd/

Remains of lost Viking army that made England discovered

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A lost Viking army which was a “key part” of the creation of England may have been identified by archaeologists.

More than 250 skeletons found at St Wystan’s church, Repton, Derbyshire, have been dated to the 9th Century.

Chronicles state a “large heathen army” began to hack its way across England in AD866, toppling Anglo-Saxon kings until being halted by Alfred the Great.

Cat Jarman from the University of Bristol said: “This army had left almost no trace, but maybe here it is.”

In AD866 the Vikings went from ferocious raiders to an invading force – the Viking Great Army had arrived.

Ms Jarman, from the department of Anthropology and Archaeology, said: “This was a key part in the story of how England was made.

“The defeat of Anglo-Saxon kingdoms, the creation of a Viking state and Alfred’s reaction to it were all major parts of this. Its echoes are still felt today.

“But because of the lack of physical evidence it has not been given the attention it deserves.”

The Viking army was believed to have wintered at Repton in AD873 but the evidence did not add up.

A mysterious mound in St Wystan’s church yard excavated in the 1970s and 80s contained the remains of at least 264 people.

But nearly 20% were women and there were few signs of battle injuries.

Carbon dating showed bones dating from the 200 years previous to the Viking invasion.

Ms Jarman said: “We found the carbon dating had been thrown out by those individuals having a diet high in seafood.

“Once adjusted, the dates matched the records.

“And a new analysis of the bones… showed traumatic injury, while the role of women in Viking armies is better understood.”

Other graves with probable Viking links were investigated, and one may contain sacrificial victims.

Four children, aged eight to 18, were buried near the mass grave and at least two have signs of traumatic injury.

Ms Jarman said it “parallels accounts of sacrificial killings to accompany Viking dead”.

http://www.bbc.com/news/uk-england-42918121

Laser Scans Reveal Maya Vast Interconnected “Megalopolis” Below Guatemalan Jungle that was Home to Millions of People

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Laser technology known as LiDAR digitally removes the forest canopy to reveal ancient ruins below, showing that Maya cities such as Tikal were much larger than ground-based research had suggested.

By Tom Clynes

In what’s being hailed as a “major breakthrough” in Maya archaeology, researchers have identified the ruins of more than 60,000 houses, palaces, elevated highways, and other human-made features that have been hidden for centuries under the jungles of northern Guatemala.


Laser scans revealed more than 60,000 previously unknown Maya structures that were part of a vast network of cities, fortifications, farms, and highways.

Using a revolutionary technology known as LiDAR (short for “Light Detection And Ranging”), scholars digitally removed the tree canopy from aerial images of the now-unpopulated landscape, revealing the ruins of a sprawling pre-Columbian civilization that was far more complex and interconnected than most Maya specialists had supposed.

“The LiDAR images make it clear that this entire region was a settlement system whose scale and population density had been grossly underestimated,” said Thomas Garrison, an Ithaca College archaeologist and National Geographic Explorer who specializes in using digital technology for archaeological research.

Garrison is part of a consortium of researchers who are participating in the project, which was spearheaded by the PACUNAM Foundation, a Guatemalan nonprofit that fosters scientific research, sustainable development, and cultural heritage preservation.

The project mapped more than 800 square miles (2,100 square kilometers) of the Maya Biosphere Reserve in the Petén region of Guatemala, producing the largest LiDAR data set ever obtained for archaeological research.

The results suggest that Central America supported an advanced civilization that was, at its peak some 1,200 years ago, more comparable to sophisticated cultures such as ancient Greece or China than to the scattered and sparsely populated city states that ground-based research had long suggested.

In addition to hundreds of previously unknown structures, the LiDAR images show raised highways connecting urban centers and quarries. Complex irrigation and terracing systems supported intensive agriculture capable of feeding masses of workers who dramatically reshaped the landscape.

The ancient Maya never used the wheel or beasts of burden, yet “this was a civilization that was literally moving mountains,” said Marcello Canuto, a Tulane University archaeologist and National Geographic Explorer who participated in the project.

“We’ve had this western conceit that complex civilizations can’t flourish in the tropics, that the tropics are where civilizations go to die,” said Canuto, who conducts archaeological research at a Guatemalan site known as La Corona. “But with the new LiDAR-based evidence from Central America and [Cambodia’s] Angkor Wat, we now have to consider that complex societies may have formed in the tropics and made their way outward from there.”

“LiDAR is revolutionizing archaeology the way the Hubble Space Telescope revolutionized astronomy,” said Francisco Estrada-Belli, a Tulane University archaeologist and National Geographic Explorer. “We’ll need 100 years to go through all [the data] and really understand what we’re seeing.”

The unaided eye sees only jungle and an overgrown mound, but LiDAR and augmented reality software reveal an ancient Maya pyramid.

Already, though, the survey has yielded surprising insights into settlement patterns, inter-urban connectivity, and militarization in the Maya Lowlands. At its peak in the Maya classic period (approximately A.D. 250–900), the civilization covered an area about twice the size of medieval England, but it was far more densely populated.

“Most people had been comfortable with population estimates of around 5 million,” said Estrada-Belli, who directs a multi-disciplinary archaeological project at Holmul, Guatemala. “With this new data it’s no longer unreasonable to think that there were 10 to 15 million people there—including many living in low-lying, swampy areas that many of us had thought uninhabitable.”


Hidden deep in the jungle, the newly-discovered pyramid rises some seven stories high but is nearly invisible to the naked eye.

Virtually all the Mayan cities were connected by causeways wide enough to suggest that they were heavily trafficked and used for trade and other forms of regional interaction. These highways were elevated to allow easy passage even during rainy seasons. In a part of the world where there is usually too much or too little precipitation, the flow of water was meticulously planned and controlled via canals, dikes, and reservoirs.

Among the most surprising findings was the ubiquity of defensive walls, ramparts, terraces, and fortresses. “Warfare wasn’t only happening toward the end of the civilization,” said Garrison. “It was large-scale and systematic, and it endured over many years.”

The survey also revealed thousands of pits dug by modern-day looters. “Many of these new sites are only new to us; they are not new to looters,” said Marianne Hernandez, president of the PACUNAM Foundation. (Read “Losing Maya Heritage to Looters.”)

Environmental degradation is another concern. Guatemala is losing more than 10 percent of its forests annually, and habitat loss has accelerated along its border with Mexico as trespassers burn and clear land for agriculture and human settlement.

“By identifying these sites and helping to understand who these ancient people were, we hope to raise awareness of the value of protecting these places,” Hernandez said.

The survey is the first phase of the PACUNAM LiDAR Initiative, a three-year project that will eventually map more than 5,000 square miles (14,000 square kilometers) of Guatemala’s lowlands, part of a pre-Columbian settlement system that extended north to the Gulf of Mexico.

“The ambition and the impact of this project is just incredible,” said Kathryn Reese-Taylor, a University of Calgary archaeologist and Maya specialist who was not associated with the PACUNAM survey. “After decades of combing through the forests, no archaeologists had stumbled across these sites. More importantly, we never had the big picture that this data set gives us. It really pulls back the veil and helps us see the civilization as the ancient Maya saw it.”

https://news.nationalgeographic.com/2018/02/maya-laser-lidar-guatemala-pacunam/

Thanks to Kebmodee for bringing this to the It’s Interesting community.

The Voynich Manuscript

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The pages of the Voynich Manuscript, estimated to have been written between 1404-1438, have puzzled researchers for over a century.

by Michael d’Estries

The 600-year-old book no one can read has been fascinating us for decades, but we’re only recently starting to learn more about it.

Named after the Polish-American bookseller Wilfrid M. Voynich, who acquired it in 1912, the Voynich Manuscript is a detailed 240-page book written in a language or script that is completely unknown.

Some folks have labelled the Voynich Manuscript as nothing more than an ancient hoax, including Gordon Rugg of Keele University in the U.K., who has spent more than a decade studying the manuscript. Rugg writes in a 2016 paper that the text would be easy to fake if the author was familiar with simple coding techniques. “We have known for years that the syllables are not random. There are ways of producing gibberish which are not random in a statistical sense,” he told New Scientist. “It’s a bit like rolling loaded dice. If you roll dice that are subtly loaded, they would come up with a six more often than you would expect, but not every time.”

But other researchers don’t necessarily agree. In a 2013 study published in the journal PLoS One, Dr. Diego Amancio, a professor at University of São Paulo’s Institute of Mathematical and Computer Sciences, explained how the book’s beautiful gibberish is likely an actual language.

“We show that it is mostly compatible with natural languages and incompatible with random texts,” he writes. “We also obtain candidates for keywords of the Voynich Manuscript, which could be helpful in the effort of deciphering it.”


Deciphering it with artificial intelligence

More recently, Greg Kondrak, an expert in natural language processing at the University of Alberta, used artificial intelligence to try to crack the code. With the help of his grad student, Bradley Hauer, Kondrak used samples from “Universal Declaration of Human Rights,” which was written in nearly 400 languages, running algorithms to identify the language of the text. Although they hypothesized it was written in Arabic, it turned out the most likely language was Hebrew.

The researchers hypothesized the manuscript was created using alphagrams, where the letters of a word are replaced in alphabetical order. With that assumption, they tried to create an algorithm to read the text.

“It turned out that over 80 percent of the words were in a Hebrew dictionary, but we didn’t know if they made sense together,” said Kondrak, in a statement.

After being unable to find Hebrew scholars to confirm their findings, the researchers turned to Google Translate. “It came up with a sentence that is grammatical, and you can interpret it,” said Kondrak, “she made recommendations to the priest, man of the house and me and people. It’s a kind of strange sentence to start a manuscript but it definitely makes sense.”

Without historians of ancient Hebrew, Kondrak said that the full meaning of the Voynich manuscript will remain a mystery.


The beautifully illustrated plants that fill up the pages of the Voynich Manuscript have never been accurately identified.


Bringing the puzzle to the people

It may seem far-fetched, but this famous manuscript could become a bestseller.

Siloe, a small publishing house in Spain specializing in handcrafted replicas of ancient manuscripts, in 2016 was granted the exclusive rights to create 898 facsimiles of the Voynich.

“It’s a book that has such an aura of mystery that when you see it for the first time, it fills you with an emotion that is very hard to describe,” Juan Jose Garcia, the editor of Siloe, told AFP.

No ordinary scan-and-print project, the Voynich replicas will be meticulously crafted to match every “stain, hole, and sewn-up tear in the parchment,” according to the news agency. The publishing house has even created a secret paste and aging process to make the more than 200 pages of the book appear and feel indistinguishable from the real thing. The process is expected to take a full 18 months to complete.

Siloe had reportedly been petitioning the Beinecke Rare Book & Manuscript Library at Yale, which took possession of the Voynich in 1969, to publish a replica for the last 10 years. The library finally acquiesced after both an increase in scholarly interest in the Voynich and quality assurances from experts associated with previous rare manuscript copies completed by Siloe.

“We thought that the facsimile would provide the look and feel of the original for those who were interested,” Raymond Clemens, curator at the Beinecke library, told the AFP. “It also enables libraries and museums to have a copy for instructional purposes and we will use the facsimile ourselves to show the manuscript outside of the library to students or others who might be interested.”


A work of curious art

Besides its indecipherable characters, the manuscript is also crammed with illustrations of astronomical charts, human figures, and plants, the latter of which have never been positively identified as anything found on Earth. These puzzles have led to the manuscript being classified as everything from the work of aliens to the musings of an inter-dimensional Medieval sorcerer.

Whatever the true answer, you don’t have to shell out the expected $8,000 to $9,000 cost for an exact replica. In addition to offering high-res digital scans of the Voynich pages online, Yale is selling hardcover copies for $50 that include accompanying research on the manuscript.

You can also view a digital overview of the 250 pages of the Voynich Manuscript in the video below.

https://www.mnn.com/green-tech/research-innovations/blogs/publisher-replicate-600-year-old-Voynich-manuscript

Ancient Swedish ritual of the ‘year walk’: Årsgång

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by Starre Vartan

This Swedish ritual reportedly helps people see the future. Start by spending your daylight hours shut in a dark room. No eating, speaking, sleeping or engaging with technology or the outside world for a whole day. By cutting yourself off in this manner, you’re preparing your mind and spirit for the Swedish pseudo-pagan ritual of Årsgång, or the “year walk.”

Next, leave your home when the clock strikes 12. Alone in the dark, walk to the local church or house of worship. This ritual can only be done at midnight, preferably on the winter solstice or Christmas, but another winter’s eve of your choosing will work. When you arrive, walk around the building three times counterclockwise, then blow in the keyhole of the front door. (This is to temporarily renounce any attachments you may have to religion.)

Once you’ve completed these steps, you will have opened yourself up to enter the spirit world — and you may even be able to see the future.

When pagan beliefs and rituals were at their height in Scandinavia, some people were known to disappear during these walks, while others were rewarded with seeing what was ahead personally or for those in their community.

“The walker might gain information about marriage, the harvest, the possibility of war, or if there will be fires, but the most common information was about who was going to die in the upcoming year,” explains Atlas Obscura.

A year-walker might also see visions, like the brook horse, which gathers children on its back and then plunges into the water with them, drowning them all. Or the huldra, “a deceptively beautiful female entity, who often had bark and treelike features growing on her back instead of skin. Said to be the forest guardians, they would lure people to their homes to either marry them or kill them. Either way, the victim would be lost forever,” according to this page on folklore from the University of Southern California.

When the walker was ready for the experience to be over, he would return to the church and reclaim his faith.

A team at Swedish video game maker Simogo developed a game for smartphones based on the year walk. You can see a trailer for the immersive game set in a snowy landscape in the video below:

“We based [the game] off folklore in a very unscientific way,” the writer of the game, Jonas Tarestad, told Atlas Obscura. “In a way we recreated the word-of-mouth process of the past and added our own details. In the end we had sort of lost the grasp of what parts we made up to fit the game and what parts were original folklore.”

Following an outdoor lesson in nature, children were more engaged with their schoolwork, and their teachers could teach uninterrupted for almost twice as long.

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By Conn Hastings

A study recently published in open-access journal Frontiers in Psychology finds that 9-10 year-old children are significantly more attentive and engaged with their schoolwork following an outdoor lesson in nature. This “nature effect” allowed teachers to teach uninterrupted for almost twice as long during a subsequent indoor lesson. The results suggest that outdoor lessons may be an inexpensive and convenient way to improve student engagement in education — a major factor in academic achievement.

Scientists have known for a while that natural outdoor environments can have a variety of beneficial effects on people. People exposed to parks, trees or wildlife can experience benefits such as physical activity, stress reduction, rejuvenated attention and increased motivation. In children, studies have shown that even a view of greenery through a classroom window could have positive effects on students’ attention.

However, many teachers may be reluctant to hold a lesson outdoors, as they might worry that it could overexcite the children, making it difficult for them to concentrate on their schoolwork back in the classroom. Ming Kuo, a scientist at the University of Illinois at Urbana-Champaign, and her colleagues set out to investigate this, and hypothesized that an outdoor lesson in nature would result in increased classroom engagement in indoor lessons held immediately afterwards.

“We wanted to see if we could put the nature effect to work in a school setting,” says Kuo. “If you took a bunch of squirmy third-graders outdoors for lessons, would they show a benefit of having a lesson in nature, or would they just be bouncing off the walls afterward?”

The researchers tested their hypothesis in third graders (9-10 years old) in a school in the Midwestern United States. Over a 10-week period, an experienced teacher held one lesson a week outdoors and a similar lesson in her regular classroom, and another, more skeptical teacher did the same. Their outdoor “classroom” was a grassy spot just outside the school, in view of a wooded area.

After each outdoor or indoor lesson, the researchers measured how engaged the students were. They counted the number of times the teacher needed to redirect the attention of distracted students back to their schoolwork during the observation, using phrases such as “sit down” and “you need to be working”. The research team also asked an outside observer to look at photos taken of the class during the observation period and score the level of class engagement, without knowing whether the photos were taken after an indoor or outdoor lesson. The teachers also scored class engagement.

The team’s results show that children were more engaged after the outdoor lessons in nature. Far from being overexcited and inattentive immediately after an outdoor lesson, students were significantly more attentive and engaged with their schoolwork. The number of times the teacher had to redirect a student’s attention to their work was roughly halved immediately after an outdoor lesson.

“Our teachers were able to teach uninterrupted for almost twice as long at a time after the outdoor lesson,” says Kuo, “and we saw the nature effect with our skeptical teacher as well.”

The researchers plan to do further work to see if the technique can work in other schools and for less experienced teachers. If so, regular outdoor lessons could be an inexpensive and convenient way for schools to enhance student engagement and performance. “We’re excited to discover a way to teach students and refresh their minds for the next lesson at the same time,” says Kuo. “Teachers can have their cake and eat it too.”

Children more engaged and attentive following outdoor lesson in nature

Uncovering the early origins of Huntington’s disease

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Huntington’s neurons show multiple nuclei (blue) within the same cell, and other signs of trouble, long before symptoms emerge.

With new findings, scientists may be poised to break a long impasse in research on Huntington’s disease, a fatal hereditary disorder for which there is currently no treatment.

One in 10,000 Americans suffer from the disease, and most begin to show symptoms in middle age as they develop jerky movements—and as these patients increasingly lose brain neurons, they slide into dementia. But the new research suggests that these symptoms may be a late manifestation of a disease that originates much earlier, in the first steps of embryonic development.

A team at Rockefeller led by Ali Brivanlou, the Robert and Harriet Heilbrunn Professor, developed a system to model Huntington’s in human embryonic stem cells for the first time. In a report published in Development, they describe early abnormalities in the way Huntington’s neurons look, and how these cells form larger structures that had not previously been associated with the disease.

“Our research supports the idea that the first domino is pushed soon after fertilization,” Brivanlou says, “and that has consequences down the line. The final domino falls decades after birth, when the symptoms are observable.”

The findings have implications for how to best approach treating the disorder, and could ultimately lead to effective therapies.

A new tool

Huntington’s is one of the few diseases with a straightforward genetic culprit: One hundred percent of people with a mutated form of the Huntingtin (HTT) gene develop the disease. The mutation takes the form of extra DNA, and causes the gene to produce a longer-than-normal protein. The DNA itself appears in the form of a repeating sequence, and the more repeats there are, the earlier the disease sets in.

Research on Huntington’s has thus far relied heavily on animal models of the disease, and has left many key questions unanswered. For example, scientists have not been able to resolve what function the HTT gene serves normally, or how its mutation creates problems in the brain.

Suspecting that the disease works differently in humans, whose brains are much bigger and more complex than those of lab animals, Brivanlou, along with research associates Albert Ruzo and Gist Croft, developed a cell-based human system for their research. They used the gene editing technology CRISPR to engineer a series of human embryonic stem cell lines, which were identical apart from the number of DNA repeats that occurred at the ends of their HTT genes.

“We started seeing things that were completely unexpected,” says Brivanlou. “In cell lines with mutated HTT, we saw giant cells. It looked like a jungle of disorganization.”

When cells divide, they typically each retain one nuclei. However, some of these enlarged, mutated cells flaunted up to 12 nuclei—suggesting that neurogenesis, or the generation of new neurons, was affected. The disruption was directly proportional to how many repeats were present in the mutation: The more repeats there were, the more multinucleated neurons appeared.

“Our work adds to the evidence that there is an unrecognized developmental aspect to the pathology,” Brivanlou says. “Huntington’s may not be just a neurodegenerative disease, but also a neurodevelopmental disease.”

Toxic or essential?

Treatments for Huntington’s have typically focused on blocking the activity of the mutant HTT protein, the assumption being that the altered form of the protein was more active than normal, and therefore toxic to neurons. However, Brivanlou’s work shows that the brain disruption may actually be due to a lack of HTT protein activity.

To test its function, the researchers created cell lines that completely lacked the HTT protein. These cells turned out to be very similar to those with Huntington’s pathology, corroborating the idea that a lack of the protein—not an excess of it—is driving the disease.

The findings are significant, Brivanlou notes, since they indicate that existing treatments that were designed to block HTT activity may actually do more harm than good.

“We should rethink our approach to treating Huntington’s,” he says. “Both the role of the HTT protein and the timing of treatment need to be reconsidered; by the time a patient is displaying symptoms, it may be too late to medicate. We need to go back to the earliest events that trigger the chain reaction that ultimately results in disease so we can focus new therapies on the cause, not the consequences.”

The researchers hope their new cell lines will be a useful resource for studying the cellular and molecular intricacies of Huntington’s further, and suggest they may provide a model for examining other diseases of the brain that are specific to humans.

https://www.rockefeller.edu/news/21212-uncovering-early-origins-huntingtons-disease/

Neuroscience can tell who are friends are by looking at the response of our brains to video clips

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You may perceive the world the way your friends do, according to a Dartmouth study finding that friends have similar neural responses to real-world stimuli and these similarities can be used to predict who your friends are.

The researchers found that you can predict who people are friends with just by looking at how their brains respond to video clips. Friends had the most similar neural activity patterns, followed by friends-of-friends who, in turn, had more similar neural activity than people three degrees removed (friends-of-friends-of-friends).

Published in Nature Communications, the study is the first of its kind to examine the connections between the neural activity of people within a real-world social network, as they responded to real-world stimuli, which in this case was watching the same set of videos.

“Neural responses to dynamic, naturalistic stimuli, like videos, can give us a window into people’s unconstrained, spontaneous thought processes as they unfold. Our results suggest that friends process the world around them in exceptionally similar ways,” says lead author Carolyn Parkinson, who was a postdoctoral fellow in psychological and brain sciences at Dartmouth at the time of the study and is currently an assistant professor of psychology and director of the Computational Social Neuroscience Lab at the University of California, Los Angeles.

The study analyzed the friendships or social ties within a cohort of nearly 280 graduate students. The researchers estimated the social distance between pairs of individuals based on mutually reported social ties. Forty-two of the students were asked to watch a range of videos while their neural activity was recorded in a functional magnetic resonance imaging (fMRI) scanner. The videos spanned a range of topics and genres, including politics, science, comedy and music videos, for which a range of responses was expected. Each participant watched the same videos in the same order, with the same instructions. The researchers then compared the neural responses pairwise across the set of students to determine if pairs of students who were friends had more similar brain activity than pairs further removed from each other in their social network.

Figure 1 from paper: Social network. The social network of an entire cohort of first-year graduate students was reconstructed based on a survey completed by all students in the cohort (N = 279; 100% response rate). Nodes indicate students; lines indicate mutually reported social ties between them. A subset of students (orange circles; N = 42) participated in the fMRI study. Image by Carolyn Parkinson.

The findings revealed that neural response similarity was strongest among friends, and this pattern appeared to manifest across brain regions involved in emotional responding, directing one’s attention and high-level reasoning. Even when the researchers controlled for variables, including left-handed- or righthandedness, age, gender, ethnicity, and nationality, the similarity in neural activity among friends was still evident. The team also found that fMRI response similarities could be used to predict not only if a pair were friends but also the social distance between the two.

“We are a social species and live our lives connected to everybody else. If we want to understand how the human brain works, then we need to understand how brains work in combination— how minds shape each other,” explains senior author Thalia Wheatley, an associate professor of psychological and brain sciences at Dartmouth, and principal investigator of the Dartmouth Social Systems Laboratory.

For the study, the researchers were building on their earlier work, which found that as soon as you see someone you know, your brain immediately tells you how important or influential they are and the position they hold in your social network.

The research team plans to explore if we naturally gravitate toward people who see the world the same way we do, if we become more similar once we share experiences or if both dynamics reinforce each other.

http://www.nature.com/articles/s41467-017-02722-7

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