Category: Science News

{People who drink wine, liquor or beer regularly are less prone to heart failure and heart attacks than those who rarely or never drink. Three to five drinks a week can be good for your heart.}

People who drink wine, liquor or beer regularly are less prone to heart failure and heart attacks than those who rarely or never drink. Three to five drinks a week can be good for your heart.

Drinking a little alcohol every day may be part of a healthy lifestyle, according to Imre Janszky, a professor of social medicine at the Norwegian University of Science and Technology (NTNU). He says alcohol does more good than harm for your heart when consumed in moderation.

And, Janszky says, it doesn’t matter much whether you drink wine, liquor or beer.

“It’s primarily the alcohol that leads to more good cholesterol, among other things. But alcohol can also cause higher blood pressure. So it’s best to drink moderate amounts relatively often,” he says.

Decreased risk with each additional serving

Along with a number of colleagues from NTNU and the Karolinska Institute in Stockholm, Janszky has published two studies regarding the relationship between alcohol and heart health. One, published in the January 15 issue of the International Journal of Cardiology, is about heart failure. The second, from September 2015, is on acute myocardial infarction (AMI), and has been published in the Journal of Internal Medicine.

In both cases, research shows that people who regularly drink alcohol have better cardiovascular health than those who consume little or no alcohol.

The studies showed that those who drank three to five drinks per week were 33 per cent less prone to heart failure than those who abstained or drank infrequently. In the case of heart attacks, the risk appears to be reduced by 28 percent with each additional one-drink increment.

This does not surprise the researchers at all.

A majority of researchers worldwide seem to think three to five drinks a week can be good for your heart.

Different drinking patterns

“The relationship between alcohol and heart health has been studied in many countries, including the USA and southern European nations. The conclusions have been the same, but the drinking patterns in these countries are very different than in Norway. In countries like France and Italy, very few people don’t drink,” says Janszky. “It raises the question as to whether earlier findings can be fully trusted, if other factors related to non-drinkers might have influenced research results. It may be that these are people who previously had alcohol problems, and who have stopped drinking completely,” he says.

For this reason, the researchers wanted to examine the theory with a Norwegian population where a significant population drinks rarely or not at all. In the myocardial infarction study, 41 per cent of participants reported that they did not drink at all or that they consumed less than half of one alcoholic beverage per week.

Both studies are based on the longitudinal HUNT 2 Nord-Trøndelag Health Study conducted between 1995 and 1997.

The greater the drinking frequency, the lower the risk

The study, which looked at the relationship between heart failure and alcohol, followed 60,665 participants who enrolled in the HUNT study between 1995-1997 and who had no incidence of heart failure at that time. Of those, 1588 of them developed heart failure during the period of the study, which ended in 2008. The risk was highest for those who rarely or never drank alcohol, and for those who had an alcohol problem.

The more often participants consumed alcohol within normal amounts, the lower their risk of heart failure turned out to be. Those who drank five or more times a month had a 21 per cent lower risk compared to non-drinkers and those who drank little, while those who drank between one and five times a month had a two per cent lower risk.

Drinking isn’t necessary for a healthy heart

“I’m not encouraging people to drink alcohol all the time. We’ve only been studying the heart, and it’s important to emphasize that a little alcohol every day can be healthy for the heart. But that doesn’t mean it’s necessary to drink alcohol every day to have a healthy heart,” says Janszky.

In the heart attack study, 58,827 participants were categorized by how much and how often they drank. 2966 of the participants experienced an acute myocardial infarction (AMI) between 1995 and the end of 2008. The adjusted analyses showed that each additional one-drink increment decreased the risk of AMI by 28 percent.

Alcohol may increase other problems

The researchers stressed that few participants in the study drank particularly much, so they cannot conclude that high alcohol intake protects against heart attack or heart failure. They also encourage looking at the findings in a larger context, since the risk of a number of other diseases and social problems can increase as a result of higher alcohol consumption.

For example, the researchers observed that the risk of dying from various types of cardiovascular disease increased with about five drinks a week and up, while those who drank more moderate amounts had the lowest risk. High alcohol consumption was also strongly associated with an increased risk of death from liver disease.

Source:Science Daily:[Light-to-moderate drinking good for your heart->https://www.sciencedaily.com/releases/2016/02/160218060941.htm]

{Humans and Neandertals may have hooked up much earlier than previously thought.}

Early ancestors of humans in Africa interbred with Neandertals about 110,000 years ago, an international group of researchers reports online February 17 in Nature. That genetic mixing left its mark on the DNA of a Siberian Neandertal, the researchers have discovered. While many humans today carry bits of Neandertal DNA, this is the first time human DNA has been found embedded in a Neandertal’s genes.

If the finding is correct, it indicates that the relationship between humans and Neandertals goes further back and is more complicated than scientists supposed, says Sarah Tishkoff, an evolutionary geneticist at the University of Pennsylvania who was not involved in the study.

Geneticists knew that early modern humans and Neandertals mated about 47,000 to 65,000 years ago (SN: 6/13/15, p. 11). Evidence of that Stone Age interbreeding was uncovered when researchers found traces of Neandertal DNA slipped into the pages of the human genetic instruction book. Today, about 1.5 percent to 4 percent of the genomes of non-Africans is made up of Neandertal DNA. Some of that DNA may increase the risk of certain diseases (SN Online: 2/11/16).

Scientists had been puzzled about why they hadn’t found signs of the interbreeding in the Neandertal genome, says Graham Coop, an evolutionary geneticist at the University of California, Davis. No one could say whether the lack of human DNA in Neandertals was due to biology or cultural practices — such as shunning hybrid children — preventing human DNA from mixing into the Neandertal gene pool or simply a product of missing data, as DNA from very few Neandertals is available. The new finding indicates that DNA traveled both ways, he says.

About 1 percent to 7.1 percent of a 50,000 year-old Siberian Neandertal woman’s DNA contains traces of human DNA, Adam Siepel, a computational biologist at Cold Spring Harbor Laboratory in New York and colleagues discovered. That woman’s toe bone, found in the same cave in the Altai Mountains as the only known fossils of extinct human cousins call Denisovans, yielded some of the most well-preserved Neandertal DNA ever analyzed (SN: 1/25/14, p. 17).

Siepel and colleagues lined up the Altai Neandertal’s DNA from chromosome 21 and compared it with chromosome 21 DNA from modern humans and from two other Neandertals, one from El Sidrón Cave in Spain and one from Vindija Cave in Croatia. The Altai Neandertal shared more DNA with modern humans than the two European Neandertals did, the team found. That result indicates that there was little, if any, mixing between early human groups and populations that led to the European Neandertals, Siepel says.

Early humans must have left their bookmarking DNA in the Altai genetic instruction manual after the Neandertal woman’s ancestors went their separate ways from the European Neandertals. That split occurred between 68,000 and 167,000 years ago.

Exactly who the humans were who mated with the Altai Neandertal’s ancestors isn’t clear. Those humans appear to be equally related to all present-day Africans. They could be direct ancestors of all Africans. Or they could have belonged to a group that split off from the population that would give rise to today’s Africans, but didn’t leave any modern descendants. “Perhaps we’re getting a glimpse of populations that just didn’t make it,” Tishkoff says.

Also unknown is where the early interbreeding happened, Siepel says. “This is all sort of reading tea leaves.” More Neandertal DNA could help pinpoint where and when humans and Neandertals first mixed.

Siepel says some hypotheses about human migration may now need rethinking in light of the new genetic evidence. “The timeline is hard to reconcile with a dominant model of human evolution with a single major migration out of Africa about 50,000 to 60,000 years ago,” Siepel says. His group’s finding “points fairly strongly to an earlier migration out of Africa.”

{The first direct evidence that humans played a substantial role in the extinction of the huge, wondrous beasts inhabiting Australia some 50,000 years ago — in this case a 500-pound bird — has been discovered research team.}

The first direct evidence that humans played a substantial role in the extinction of the huge, wondrous beasts inhabiting Australia some 50,000 years ago — in this case a 500-pound bird — has been discovered by a University of Colorado Boulder-led team.

The flightless bird, known as Genyornis newtoni, was nearly 7 feet tall and appears to have lived in much of Australia prior to the establishment of humans on the continent 50,000 years ago, said CU-Boulder Professor Gifford Miller. The evidence consists of diagnostic burn patterns on Genyornis eggshell fragments that indicate humans were collecting and cooking its eggs, thereby reducing the birds’ reproductive success.

“We consider this the first and only secure evidence that humans were directly preying on now-extinct Australian megafauna,” said Miller, associate director of CU-Boulder’s Institute of Arctic and Alpine Research. “We have documented these characteristically burned Genyornis eggshells at more than 200 sites across the continent.”

A paper on the subject appears online Jan. 29, in Nature Communications.

In analyzing unburned Genyornis eggshells from more than 2,000 localities across Australia, primarily from sand dunes where the ancient birds nested, several dating methods helped researchers determine that none were younger than about 45,000 years old. Burned eggshell fragments from more than 200 of those sites, some only partially blackened, suggest pieces were exposed to a wide range of temperatures, said Miller, a professor in CU-Boulder’s Department of Geological Sciences.

Optically stimulated luminescence dating, a method used to determine when quartz grains enclosing the eggshells were last exposed to sunlight, limits the time range of burned Genyornis eggshell to between 54,000 and 44,000 years ago. Radiocarbon dating indicated the burnt eggshell was no younger than about 47,000 years old.

The blackened fragments were likely burned in transient, human fires — presumably to cook the eggs — rather than in wildfires, he said.

Amino acids — the building blocks of proteins -decompose in a predictable fashion inside eggshells over time. In eggshell fragments burned at one end but not the other, there is a tell-tale “gradient” from total amino acid decomposition to minimal amino acid decomposition, he said. Such a gradient could only be produced by a localized heat source, likely an ember, and not from the sustained high heat produced regularly by wildfires on the continent both in the distant past and today.

Miller also said the researchers found many of the burnt Genyornis eggshell fragments in tight clusters less than 10 feet in diameter, with no other eggshell fragments nearby. Some individual fragments from the same clusters had heat gradient differences of nearly 1,000 degrees Fahrenheit, conditions virtually impossible to reproduce with natural wildfires there, he said.

“We can’t come up with a scenario that a wildfire could produce those tremendous gradients in heat,” Miller said. “We instead argue that the conditions are consistent with early humans harvesting Genyornis eggs, cooking them over fires, and then randomly discarding the eggshell fragments in and around their cooking fires.”

Another line of evidence for early human predation on Genyornis eggs is the presence of ancient, burned eggshells of emus — flightless birds weighing only about 100 pounds and which still exist in Australia today — in the sand dunes. Emu eggshells exhibiting burn patterns similar to Genyornis eggshells first appear on the landscape about 50,000 years ago, signaling they most likely were scorched after humans arrived in Australia, and are found fairly consistently to modern times, Miller said.

The Genyornis eggs are thought to have been roughly the size of a cantaloupe and weighed about 3.5 pounds, Miller said.

Genyornis roamed the Australian outback with an astonishing menagerie of other now-extinct megafauna that included a 1,000-pound kangaroo, a 2-ton wombat, a 25-foot-long-lizard, a 300-pound marsupial lion and a Volkswagen-sized tortoise. More than 85 percent of Australia’s mammals, birds and reptiles weighing over 100 pounds went extinct shortly after the arrival of the first humans.

The demise of the ancient megafauna in Australia (and on other continents, including North America) has been hotly debated for more than a century, swaying between human predation, climate change and a combination of both, said Miller. While some still hold fast to the climate change scenario — specifically the continental drying in Australia from about 60,000 to 40,000 years ago — neither the rate nor magnitude of that change was as severe as earlier climate shifts in Australia during the Pleistocene epoch, which lacked the punch required to knock off the megafauna, said Miller.

Miller and others suspect Australia’s first inhabitants traveled to the northern coast of the continent on rafts launched from Indonesian islands several hundred miles away. “We will never know the exact time window humans arrived on the continent,” he said. “But there is reliable evidence they were widely dispersed across the continent before 47,000 years ago.”

Evidence of Australia megafauna hunting is very difficult to find, in part because the megafauna there are so much older than New World megafauna and in part because fossil bones are easily destroyed by the chemistry of Australian soils. said Miller.

“In the Americas, early human predation on the giant animals in clear — stone spear heads are found embedded in mammoth bones, for example,” said Miller. “The lack of clear evidence regarding human predation on the Australia megafauna had, until now, been used to suggest no human-megafauna interactions occurred, despite evidence that most of the giant animals still roamed Australia when humans colonized the continent.”

{The moon was formed by a violent, head-on collision between the early Earth and a “planetary embryo” called Theia approximately 100 million years after the Earth formed, UCLA geochemists and colleagues report.}

Scientists had already known about this high-speed crash, which occurred almost 4.5 billion years ago, but many thought the Earth collided with Theia (pronounced THAY-eh) at an angle of 45 degrees or more — a powerful side-swipe (simulated in this 2012 YouTube video). New evidence reported Jan. 29 in the journal Science substantially strengthens the case for a head-on assault.

The researchers analyzed seven rocks brought to the Earth from the moon by the Apollo 12, 15 and 17 missions, as well as six volcanic rocks from the Earth’s mantle — five from Hawaii and one from Arizona.

The key to reconstructing the giant impact was a chemical signature revealed in the rocks’ oxygen atoms. (Oxygen makes up 90 percent of rocks’ volume and 50 percent of their weight.) More than 99.9 percent of Earth’s oxygen is O-16, so called because each atom contains eight protons and eight neutrons. But there also are small quantities of heavier oxygen isotopes: O-17, which have one extra neutron, and O-18, which have two extra neutrons. Earth, Mars and other planetary bodies in our solar system each has a unique ratio of O-17 to O-16 — each one a distinctive “fingerprint.”

In 2014, a team of German scientists reported in Science that the moon also has its own unique ratio of oxygen isotopes, different from Earth’s. The new research finds that is not the case.

“We don’t see any difference between the Earth’s and the moon’s oxygen isotopes; they’re indistinguishable,” said Edward Young, lead author of the new study and a UCLA professor of geochemistry and cosmochemistry.

Young’s research team used state-of-the-art technology and techniques to make extraordinarily precise and careful measurements, and verified them with UCLA’s new mass spectrometer.

The fact that oxygen in rocks on the Earth and our moon share chemical signatures was very telling, Young said. Had Earth and Theia collided in a glancing side blow, the vast majority of the moon would have been made mainly of Theia, and the Earth and moon should have different oxygen isotopes. A head-on collision, however, likely would have resulted in similar chemical composition of both Earth and the moon.

“Theia was thoroughly mixed into both the Earth and the moon, and evenly dispersed between them,” Young said. “This explains why we don’t see a different signature of Theia in the moon versus the Earth.”

Theia, which did not survive the collision (except that it now makes up large parts of Earth and the moon) was growing and probably would have become a planet if the crash had not occurred, Young said. Young and some other scientists believe the planet was approximately the same size as the Earth; others believe it was smaller, perhaps more similar in size to Mars.

Another interesting question is whether the collision with Theia removed any water that the early Earth may have contained. After the collision — perhaps tens of millions of year later — small asteroids likely hit the Earth, including ones that may have been rich in water, Young said. Collisions of growing bodies occurred very frequently back then, he said, although Mars avoided large collisions.

A head-on collision was initially proposed in 2012 by Matija ?uk, now a research scientist with the SETI Institute, and Sarah Stewart, now a professor at UC Davis; and, separately during the same year by Robin Canup of the Southwest Research Institute.

Co-authors of the Science paper are Issaku Kohl, a researcher in Young’s laboratory; Paul Warren, a researcher in the UCLA department of Earth, planetary, and space sciences; David Rubie, a research professor at Germany’s Bayerisches Geoinstitut, University of Bayreuth; and Seth Jacobson and Alessandro Morbidelli, planetary scientists at France’s Laboratoire Lagrange, Université de Nice.

The research was funded by NASA, the Deep Carbon Observatory and a European Research Council advanced grant (ACCRETE).

{Let’s talk about puppy love. Not youthful romance, but the love between a person and his or her pooch. As every dog lover knows, canine companions make for some of the best friends we could wish for. They play with us, cuddle with us, listen to us and make us feel like the most special people on the planet the moment we walk through the front door. We love them, and they love us — or so we assume. Since our furry, floppy-eared friends aren’t able to tell us how they really feel, we’re stuck staring into their puppy-dog eyes, wondering what kinds of thoughts are flying around behind them.}

The more we know as owners, the better we can promote our pets’ emotional wellness. To learn more about the doggy mind and how to nourish it, we partnered with Purina and the Purina Better With Pets Summit in search of answers to dog owners’ most pressing questions about canine psychology. And, thanks to science, we now know a lot more about what Fido and Fifi are really thinking and feeling.

“Does my dog feel guilty after he does something bad?”

We all know what it looks like: the head hanging low, ears drooping and gaze averted. It’s the look our dogs get after they’ve pooped on the living room carpet or swiped half of our breakfast while our backs were turned. But even though man’s best friend is showing all the same signs of guilt that we see in humans, that doesn’t mean he’s actually sorry. Sandra Lyn, Ph.D., a behaviorist at Nestlé Purina, says we assume that dogs feel guilty about misbehaving because we tend to anthropomorphize them, meaning we think about them as if they were human. We assume that they share our cognitive and emotional abilities, which leads us to read their behaviors the same way we would read a human’s. But, as much as we may want to deny it, dogs are not like humans — and they don’t feel guilty like humans do, either.

According to Dr. Gregory Berns, a leading neuroscientist in the field of canine cognition and author of How Dogs Love Us: A Neuroscientist and His Adopted Dog Decode the Canine Brain, the simple explanation for your dog’s guilty-seeming behavior is that he has learned to anticipate you yelling at him, and that’s why he hangs his head. And since nearly 60 percent of dog owners say their dogs’ guilty behavior causes them to scold them less, that bowed head might be your pooch’s way of reducing conflict.

“Guilt is not just an emotion,” explains Berns. “It’s also a complex cognitive process. To experience guilt you have to have reference to yourself, you have to have reference to the past, you have to remember what you did, [and you have to] know that it was something that you weren’t supposed to do. It’s not clear that dogs have all of those capabilities.” So the next time your pup tries to pull the guilt act, remember that he’s probably not sorry that he peed on your bathrobe — but he is sorry to be called out on his faux pas.

“Does my dog get jealous?”

Ah, the green-eyed monster. You’ve probably gotten the feeling that your furry friend experiences envy whenever you’re focusing on someone else because he nuzzles you or barks until he regains your attention. The truth is that while we can’t say definitively that dogs get jealous, research supports the theory. A 2014 study published in PLOS ONE showed that dogs tended to display significantly more jealous behaviors (such as getting between their owner and an object, pushing or touching their owner and snapping) when their owners showed affection for a stuffed toy dog. By contrast, they showed fewer jealous behaviors when the owners were interacting with a plastic jack-o-lantern and a children’s book. They possibly perceived more competition in the toy that they thought could be real. As anyone with more than one canine companion has likely witnessed firsthand, pups don’t take kindly to their owners doling out affection to another dog. According to the authors of the study, the findings support the view that dogs do, indeed, get jealous. Green-eyed monster, thy name is Sparky.

“Does my dog care about me?”

It should come as no surprise to pet lovers that dogs do indeed care about their owners, but what is surprising is how perceptive they are of the little things that impact you and your well-being. Research shows that dogs may be able to tell when their owners are being snubbed by someone else, and they in turn act coldly toward the people doing the dissing. In the experiment, dogs watched as their owners asked for help and either were rudely ignored or received aid. The overwhelming majority of the dogs whose owners didn’t receive help ignored food offered to them by the person who had snubbed their human. Scientists say this is likely a form of social eavesdropping, or the use of information collected by observing interactions between others, and it shows that your dog has your back.

Canine companions are also skilled at sensing our emotions. “Dogs are so good at reading [human] emotions that they will often pick up on subtle changes in voice intonation associated with affective state and respond accordingly,” explains Ragen T.S. McGowan, Ph.D., a senior behavior scientist at Nestlé Purina. “For example, [they offer] comfort when an owner is feeling down or [get] excited when their owner is in a joyous mood.” It’s a lot like the kind of care your best friend might show you during your ups and downs (no surprise, then, that dogs have earned the title of “man’s best friend”). According to a 2015 study published in Current Biology, dogs can also read emotions in our faces, perceiving through our expressions whether we’re happy, sad or angry. That explains why your pup may be more playful with you when you’re in good spirits or cuddle with you when you’re sad; they sense your emotional state and respond accordingly.

Just as dogs can sense how we’re feeling, owners can usually identify their pets’ moods based on their behaviors, too. Berns notes that dogs may actually experience emotions even more purely than humans do. “Humans have language and the capacity to almost cognitively separate themselves from experiences,” he explains, “so [we] can view [ourselves] from different perspectives and evaluate things that cause [us] to feel certain ways. That’s a uniquely human capacity.” This ability to self-analyze can blunt the sharpness of our feelings, Berns suggests, and it’s unlikely that any other animal can do the same. So while your dog undoubtedly has your back when you’re feeling down, you can bet he could use a friend when he’s feeling down, too: he may be experiencing that emotion even more intensely than we can imagine.

“What is my dog thinking when I FaceTime or Skype with her?”

So you’ve missed your dog so much while you’re away that you asked someone to help you video chat with her. (Hey, we’ve all been there, and we don’t blame you.) While getting a glimpse of your pup and saying hello over the airwaves may make you feel better and strengthen your bond, you probably can’t help but ask yourself: “Does she even know that it’s me?”

The short answer is: maybe. While dogs are experts at recognizing people by their scents, smell isn’t a factor in video chatting; dogs would instead need to rely on facial and voice recognition in order to know that it’s you. A recent study in PeerJ conducted by Berns’ team found that, like primates, dogs have a specific part of the brain that processes faces, and it’s active when dogs are viewing images of people. Still, it hasn’t been proven yet whether dogs can recognize their owners by face alone. Whatever the case, it can’t hurt to Skype — especially because it at least makes you feel closer to your canine friend, even if she can’t tell you’re on the other end.

“Does my dog love me?”

And here it is: the million-dollar question every dog owner is dying to have answered (but let’s face it, you already have your suspicions). To those who share special bonds with their pups, it may seem like a no-brainer; of course dogs love us. But others have their doubts about that bond — specifically, they wonder whether dogs have the capacity to feel love as we know it, and whether their affectionate behaviors have more to do with the fact that we provide them with food and shelter rather than with the L word.

Berns suggests that the question of whether dogs truly love their humans depends on the dog and on the person. Just as some human relationships are transactional in nature — for instance, you can love someone because they make you feel a certain way — part of dogs’ affection for humans does stem from the fact that we feed them and take care of them. In some cases, though, he believes that it goes “beyond that” for dogs.

“I’ve seen many dogs who just like being around their person,” Berns says. “They crave the attention, they crave the contact and they will choose that over food. Is that love? I would call it that, yes. We call it that in humans.” It’s also possible that some breeds of dogs may be more likely than others to develop that strong bond with their humans. Researchers, including Berns, are exploring that very question in order to determine if some furry friends may make better service dogs than others.

Studies support the theory that dogs do feel the warm-and-fuzzies for their humans — even more so than for their animal friends. In a study published in ScienceDirect in 2015, Berns and his colleagues presented dogs with the scents of their owner, a human they didn’t know, a familiar dog (usually one that lived in the same home), an unfamiliar dog and the subject dogs’ own scent. They used fMRI technology to monitor the dogs’ brain activity, and they found that of all the scents, only the familiar human scent activated the dogs’ caudate nucleus — the part of the brain that, in humans, becomes activated when we anticipate things we like or enjoy. This suggests that dogs have a positive association with the human scent, and may in fact be experiencing feelings of love as we do.

While we can’t interpret canine behaviors the same way we interpret human ones, we can use physiological clues to guess how pups might be feeling when they’re around their owners. McGowan notes that when people come in close contact with their loved ones, they experience physiological changes, including an increase in circulating oxytocin, a hormone that plays a role in pair bonding. “The same is true for dogs being pet and cuddled by their owners,” says McGowan. “Recent work with fMRI demonstrates that dogs show increases in brain activity when their owners step back into view after having stepped out, highlighting the close connection that they share.”

They say there’s no bond quite like the one between man and his best friend, after all, and while science can’t yet say for sure whether puppy love is real, it certainly looks a lot like love, both in the behavior and in the brain.

Source:Huffington Post:[Here’s How Your Dog Really Feels About You, According To Science->http://www.huffingtonpost.com/2015/12/29/dog-psychology_n_8398778.html]

{Using optogenetics and other technology, researchers have for the first time precisely manipulated the bursting activity of cells in the brain’s thalamus, tying the alerting behavior to the sense of touch.}

As you start across the street, out of the corner of your eye, you spot something moving toward you. Instantly, your brain shifts its focus to assess the potential threat, which you quickly determine to be a slow-moving bicycle — not a car — which will pass behind you as you complete your crossing.

The brain’s ability to quickly focus on life-or-death, yes-or-no decisions, then immediately shift to detailed analytical processing, is believed to be the work of the thalamus, a small section of the midbrain through which most sensory inputs from the body flow. When cells in the thalamus detect something that requires urgent attention from the rest of the brain, they begin “bursting” — many cells firing off simultaneous signals to get the attention of the cortex. Once the threat passes, the cells quickly switch back to quieter activity.

Using optogenetics and other technology, researchers have for the first time precisely manipulated this bursting activity of the thalamus, tying it to the sense of touch. The work, done in animal models, will be reported January 14th in the journal Cell Reports. The research is supported by the National Institutes of Health’s National Institute of Neurological Disorders and Stroke.

“If you clap your hands once, that’s loud,” explained Garrett Stanley, a professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University. “But if you clap your hands several times in a row, that’s louder. And if you and your friends all clap together and at the same time, that’s even stronger. That is what these cells do, and the idea is that this mechanism produces bursts synchronized across many cells to send out a very strong signal about a stimulus in the outside world.”

Neuroscientists have long believed that such coordinated spikes of activity serve to focus the brain’s attention on issues requiring immediate attention. Stanley and graduate student Clarissa Whitmire — working with researchers Cornelius Schwarz and Christian Waiblinger from the University of Tübingen in Germany — used optogenetics techniques to study bursting activity in the thalamus of rats. Their findings could lead to a better understanding of how cells in this walnut-sized portion of the human brain perform a variety of sensory and motor control tasks, switching from one mode to another as needed.

“Clarissa was able to get into the mechanism of synchronized thalamic bursting so we can manipulate it and look at it not only from within individual cells, but also across cells, recording from multiple cells simultaneously,” said Stanley, who has been studying the thalamus for more than a decade. “We can now begin to provide a coherent story about how information gets from the outside world to the brain machinery that’s in the cortex.”

The researchers studied the connection between the rats’ whiskers and cells in their thalamus. By stimulating the whiskers in many different ways, they were able to induce signals — including bursting — in the thalamus. The researchers used light-sensitive proteins introduced into the thalamic cells — a technology known as optogenetics — to establish optical control of the bursting activity.

“We were able to turn the bursting mechanism on or off at will,” Stanley explained. “This is really the first time we have been able to readily control this, turning the knob in one direction to eliminate the bursting activity and then turning it the other way to make the cells produce these bursts in rapid succession.”

The control extended not just to turning the bursting on or off, but also allowed the researchers to create a continuum of cell activity.

“Clarissa could make them act very ‘bursty’ and very synchronized, or she could turn the knob and move them very smoothly to the opposite end of the spectrum,” Stanley said. “There is a range of activity that people had speculated would be there, but nobody had actually done the experiments to show it existed.”

The cellular bursting mechanism likely developed very early in mammalian evolution to help creatures survive threats posed by predators. The brain’s cortex is always busy with higher-level activity, and the thalamic bursting serves to let it know that critical outside activities need its urgent attention.

Other sensory inputs such as vision can initiate bursting, but Stanley’s group chose to study sense of touch in this work. In rats, the whiskers are embedded in follicles that have specialized cells whose function is similar to that of human sensory cells. Thus, these whiskers serve many of the same “touch” functions as human fingers.

“When you reach out with your hand and touch a surface, you are mechanically deforming the skin, stretching the sensors that are in the skin and sending signals to tell the brain about the surface you are touching,” Stanley noted. “In the rats, we moved the whiskers, recorded the activity, and identified the presence of a burst.”

As a next step, Stanley and his research team plan to connect what they’ve learned about bursting activity of the thalamus to behavior in an effort to fully confirm the theory. “The next step is to take this to behavior and work with animals that are trained to detect and discriminate between different kinds of inputs,” he said.

With the optogenetics and other advanced technology, researchers are beginning to see the big picture of how sensory inputs affect brain activity.

“These thalamic cells are somewhere in between the outside world and the cognitive machinery of the brain, and they have a job that changes rapidly,” Stanley said. “In some cases, they are saying ‘yes’ or ‘no’ about something in the outside world, and in some cases they are discriminating between the final details of objects in the outside world.”

{Muscles tighten, the heart pounds and nausea takes hold: In the face of sudden stress, men and women respond alike. But when threats, scares or frustrations continue for days or months, differences between the sexes emerge.}

Scientists have long known that women are more likely than men to suffer depression, post-traumatic stress disorder and other anxiety disorders, all of which have been linked to chronic stress, says Temple University psychologist Debra Bangasser. But until recently, studies of people’s responses to such stress have focused primarily on men.

Now, a growing number of scientists are studying what happens at the cellular and genetic levels in the brains of stressed-out rodents — male and female — to gain insight into the human brain. The studies are beginning to reveal differences between the sexes that may help explain the variability in their reactions and perhaps even provide much-needed insight into why stress-related disorders are more common in women than men.

Recent findings reported at the annual meeting of the Society for Neuroscience, held in Chicago in October, show that a common stress hormone triggers different responses in specific brain cells of male and female animals. The differences make females less able than males to adapt to chronic stress.

Other studies are exploring how exposure to the same hormone influences gene expression in a part of the brain that controls mood and behavior. Still other research suggests that a different hormone, associated with trust, could render females more susceptible than males to depression, anxiety and PTSD.

“Some differences may contribute to disease and some may not,” Bangasser says. “But given that it’s early days in this understudied area, we’re already finding interesting things.”

A heightened stress response may bring an evolutionary advantage. An enhanced response to stress hormones could help females — most often caregivers for the young — remain alert and ready to take action in a stressful environment.

The problems occur, Bangasser adds, “when the system is responding when it shouldn’t be or when it’s responding for a really long time in a way that becomes disruptive.”

While no one has managed to tie findings in animals to a specific behavior in people, the studies are an important first step in understanding how sex and hormones contribute to a person’s response to stress, she says. Insights from the studies also offer hope for finding ways to better detect and treat stress-related disorders in people of both sexes.

Distress signals
Differences in the male and female nervous system are established early in life. In males, sex hormones are released into the brain before and shortly after birth. Later, at puberty, sex hormones — namely, estrogen and progesterone for females and testosterone for males — exert an influence on the brains of both sexes, signaling cells to turn certain genes on or off.

Fluctuations in sex hormones over a lifetime may influence the body’s reaction to stress, for better or worse. To look at that issue, Bangasser’s group studies how estrogen, progesterone and testosterone interact with a neuropeptide called corticotropin-releasing factor, or CRF, to influence cell signaling in the brains of stressed-out rodents.

CRF acts as both a hormone and a neurotransmitter. As a hormone, it orchestrates the body’s stress response. When rodents — or people, for that matter — feel threatened or experience intense emotion, the brain secretes CRF. CRF molecules then alert the body to a potential threat when they lock on to matching receptor molecules on target cells, initiating a message that travels through the nervous system: Time to pay attention and get all hands on deck.

This arousal response is a normal, instinctive reaction designed to help individuals deal with a threat. But if this system stays on for a long time, it can create a state of constant hyper-readiness (SN: 3/7/15, p. 18).

In 2010, while in the laboratory of neurologist Rita Valentino of the University of Pennsylvania, Bangasser and colleagues found sex differences between CRF receptors in the brains of male and female rodents. The study, published in Molecular Psychiatry, showed that after a stressful 15-minute swim, females had more CRF receptors on the surface of target cells, making them very responsive to the stress hormone later on. In male rats exposed to stress, some of the CRF receptors moved from the membrane to the internal part of the nerve cell, or neuron. With fewer CRF receptors on the surface, the male rodents could better cope with similar stress in the future.

Because females don’t pull back on the number of exposed CRF receptors following a stressful event, their brains may be more responsive to high levels of CRF, even after repeated exposures to a stressful event, Bangasser says.

Recently, Bangasser’s group found that when administered in high doses, CRF increased anxiety-related grooming in both male and female rats. But female rats groomed longer and more often. Females with the highest levels of estrogen and progesterone groomed obsessively.

Bangasser’s group is now mapping the brain circuitry involved. CRF works in several brain regions, including parts of the prefrontal cortex, a brain area linked to attention and planning; the amygdala, an area that controls fear and emotional responses; and the hippocampus, which is essential to forming new memories.

Preliminary findings from her lab suggest that CRF activates these brain networks differently in males and females. Where the female is in her hormonal cycle matters as well. Sex differences in how CRF regulates the brain may explain, in part, why women may be more vulnerable than men to stress-related conditions, Bangasser says.

Environmental influences
Chronic exposure to CRF may also influence gene expression in ways that make women succumb to stress more easily.

When the body’s alarm system remains on high alert for long periods, stress hormones can cause modifications to DNA, says neuroscientist Georgia Hodes of the Icahn School of Medicine at Mount Sinai in New York City. These epigenetic modifications can alter gene activity in a way that increases vulnerability to depression and other mood disorders.

Hodes’ group found a way to reverse the damaging effects of epigenetic changes in the brains of female rodents. First, Hodes and colleagues transformed a brain structure in a young female rat, giving it malelike attributes, by injecting a drug that altered gene expression. The process, detailed in Nature Neuroscience last May, involved drugs that inhibit a family of three enzymes known as DNA methyltransferases, or Dnmts. These enzymes can alter the epigenetic marks on DNA, and thus gene activity, without changing the underlying genetic sequence.

Her team is now investigating how repeated stress alters patterns of DNA methylation — and gene activity — in the nucleus accumbens, located deep in the front part of the brain and involved in mood and behavior. Hodes and her colleagues exposed male and female mice to a variety of scares and frustrations over a period of days. The animals received foot shocks, were restrained in their cages or were briefly suspended by their tails. Throughout the experiment, researchers looked for behaviors associated with depression.

On day six, the female mice showed depression-like behaviors, which in mice include decreased grooming and fear of eating in a new environment. The mice also lost their taste for rewards such as sugar water and quickly “gave up” when challenged by new frustrations. It took until day 21 before male mice showed depression-like behaviors. The behavioral changes in females corresponded to changes in activity of a specific DNA methyltransferase called Dnmt3a.

The scientists then repeated the experiment, in a mouse genetically engineered to not produce Dnmt3a in the nucleus accumbens. Similar to resilient male mice, stressed females without Dnmt3a engaged in grooming, showed a preference for sugar water and were willing to eat in a novel environment. Findings from the study, published in the Dec. 16 Journal of Neuroscience, suggest that the removal of Dnmt3a increased the expression of genes that enabled malelike coping behaviors in the females, Hodes says.

Drugs that inhibit Dnmts are used to treat certain cancers in people, and have shown promise as medications for the treatment of mood disorders. Hodes says the findings suggest that, at least for depression and anxiety, it might be better to develop an inhibitor that just targets Dnmt3a.

“Alternatively, we can now start to examine some of the targets of Dnmt3a such as the CRF pathway and try to focus on developing a therapeutic that would act upon targets within that specific pathway,” she says.

A fine line
At the University of California, Davis, psychologist Brian Trainor has found clues to how another hormone contributes to differences in the way males and females handle stress. The results suggest that a hormone  important for social bonding  may have a dark side.

Oxytocin, known as the warm, fuzzy hormone, has been shown to slow heart rate and promote feelings of well-being. Clinical trials are under way to test the effects of a nose spray containing oxytocin on a variety of conditions, including depression, drug dependence, migraines and pain. But studies in Trainor’s lab show that elevated brain levels of oxytocin may stir more anxiety in female mice than in males after stressful experiences.

After being housed with an aggressive mouse for brief periods over three days, male and female mice alike exhibited elevated oxytocin levels in certain brain regions. And for days, both froze in fear when encountering an unfamiliar mouse. Two weeks after clashing with others, males resumed near-normal behavior around unfamiliar mice. But females remained fearful long after the event, avoiding interaction with strangers for 10 weeks. The findings were published online October 19 in Biological Psychiatry.

Examinations of brain tissue 10 weeks out show that getting bullied by a stranger increases the total number of both oxytocin-producing neurons and overall oxytocin production in a brain area in females, but not males. This area, the medioventral bed nucleus of the stria terminalis, is a primitive region located near the hypothalamus. Involved in regulating anxiety-like behaviors, this brain area can induce aversion to places or situations linked to stress, Trainor says.

Studies show women with PTSD have elevated oxytocin levels in their blood, Trainor says. “Some have considered this to be a coping mechanism to help them deal with the stress.” Not so, he says.

“Our results suggest that an increase in oxytocin-producing neurons in this brain area may be actually contributing to certain behavior changes induced by stress.”

In other studies, Trainor’s lab is looking at the kappa-opioid cell receptor, which is also activated during stressful encounters. Activated kappa-opioid receptors dampen the body’s reactions to stress, but can also depress mood. Compounds that block activity of these receptors have shown promise in humans as treatments for depression, anxiety and other psychiatric conditions, Trainor says, but studies in his lab consistently find differences in the way the sexes respond to these drugs. His group is trying to figure out the mechanisms involved.

To Trainor, the findings all point in the same direction. “It’s only a matter of time,” he says, before medications for anxiety and depression are formulated differently for men and women to account for biological differences.

Source:Science News:[His stress is not like her stress->https://www.sciencenews.org/article/his-stress-not-her-stress]