Tag Archives: rats

Empathetic rats avoid hurting other rats

Credit: Pixabay.

Most humans actively try to do all they can do to avoid harming other people. Psychologists refer to this behavioral trait as ‘harm aversion’ and it is considered a fundamental cornerstone of healthy moral development. Case in point, studies point to the fact that people with violent antisocial tendencies score low on this trait. That being said, not much has been known about how harm aversion works in the brain — until now, after researchers showed that rats also actively avoid harming their own kind.

Rodent empathy

Neuroscientists at the Netherlands Institute for Neuroscience (NIN) performed experiments with caged rats where they had the choice of pressing two levers, one of which delivered a tasty treat (sucrose pellets).

After this conditioning round, the entire setup was changed such that pressing the lever that offered candy also delivered an unpleasant electric shock to the floor of an adjacent cage where another rat was stationed. Pressing the lever caused the neighboring rat to squeak in protest.

Time after time, the rats stopped pressing the lever after they figured out that this would cause pain to the adjacent rat. This was true whether or not the neighbor had previously shared a cage with the lever-pressing rat or was a total stranger.

“Much like humans, rats thus actually find it aversive to cause harm to others” explains Dr. Julen Hernandez-Lallement, first author of the study and researcher at the NIN.

Schematic of the experiment. Credit: Christian Keysers.

Previously, brain scans showed that a brain region nestled between the two hemispheres, called the anterior cingulate cortex, lights up with activity when people empathize with the pain of a fellow human.

This same region also becomes more active in rats that witness the pain of fellow rats. According to the researchers, the rats have emotional mirror neurons that trigger the animal’s own pain neurons when another rat is harmed.

When brain activity in the rats’ anterior cingulate cortex was reduced after a local anesthetic was administered, the affected rats stopped avoiding pressing the lever that harmed the neighboring rat.

“That humans and rats use the same brain region to prevent harm to others is striking. It shows that the moral motivation that keeps us from harming our fellow humans is evolutionary old, deeply engrained in the biology of our brain and shared with other animals”, commented Dr. Valeria Gazzola, one of the senior authors of the study and group leader at the NIN.

This doesn’t necessarily mean that the study proves that rats have empathy and care about the welfare of other rats. Perhaps the rat stops pressing the lever because he simply can’t stand the squeaking noise, for instance. We can’t know for sure unless you ask the rodent and, unfortunately, that is not an option. But the same reasoning can be applied to humans also. How can we know for sure when a person acts out of altruism or selfishness?

The findings, which were published in the journal Current Biology, are extremely valuable nevertheless. More practically, they suggest that the anterior cingulate cortex can be targetted by pharmacological means to perhaps treat individuals who might engage in violent or psychopathic crimes.

“Whatever the motive, that we share a mechanism that prevents antisocial behavior with rats is extremely exciting to me. We can now use all the powerful tools of brain science to explore how to increase harm aversion in antisocial patients,” added Prof. Christian Keysers, group leader at the NIN.

This wasn’t the first time that researchers showed that rats have empathy traits. A study published all the way back in 1959 found rats refused to press a lever to obtain food when that lever also delivered a shock to a fellow rat (yes, just like this new study). Their protest was so strong that the rodents would rather starve than witness a rat suffering. Subsequent studies showed that rats refuse to follow a certain path in a maze if it resulted in a shock delivered to another rat or that rats who had been shocked themselves were less likely to allow other rats to be shocked.

In other words, rats seem to care about their fellow rat. The kind of care that seems to be in low supply among some humans.

Rats trained to drive makeshift cars seem to find it relaxing

Unlike most of us, rats seem to find driving relaxing.

The impromptu vehicle.
Image credits University of Richmond.

A team of U.S. scientists reports training a group of rats to drive tiny vehicles around in exchange for treats (Froot Loops cereal). The team found hormonal cues suggesting that the animals found driving around to be relaxing, maybe even fun and enjoyable.

The findings help showcase how even simpler brains can handle sophisticated behavior and may help inspire new treatment options for certain mental illnesses.

Rat racers

The team wanted to explore the process of neuroplasticity — the property of the brain to change in response to experience — and was particularly interested in understanding how rats housed in more natural settings perform against lab rats.

Led by senior author Kelly Lambert (University of Richmond), the team took a robot car kit, added a clear plastic food container as the driver’s compartment, and fixed an aluminum plate under that. To complete the car, a copper wire was threaded horizontally across the cab to form a left, center, and right bar.

Image credits: University of Richmond.

When a rat moved onto the aluminum floor and touched one of the wires, it would close the circuit and drive the car in the selected direction. With repetition, they learned how to drive forward and steer in more complex patterns. Seventeen rats were trained over several months to drive around an arena 150 centimeters by 60 centimeters.

All in all, the team reports that rats kept in more natural (‘enriched’) environments performed better than their lab-kept counterparts. However, Lambert herself says it “it was actually quite shocking to me that they were so much better”. In order to get a better idea of what the rats were experiencing, the team collected feces samples after the trials and tested them for corticosterone and dehydroepiandrosterone content (hormones that cause or counter stress).

All of the rats in the trial had higher levels of dehydroepiandrosterone, indicating a more relaxed state. The team says this is likely the same satisfaction we feel when we master a skill or task, known as “self-efficacy” or “agency” in humans. Furthermore, the rats that did drive showed even higher levels of dehydroepiandrosterone than those who were just passengers in a human-controlled vehicle.

While definitely cute, the study does help us better understand how rats, who are a key animal model, handle tasks and how their brains change following them. Better understanding their brains will help us better understand our own, Lambert says, and could point the way towards better treatments for mental health conditions.

“There’s no cure for schizophrenia or depression,” she said. “And we need to catch up, and I think we need to look at different animal models and different types of tasks and really respect that behavior can change our neurochemistry.”

Rat pups.

Exposure to cannabis leads to cognitive changes in the offspring of rats

Pregnancy and weed probably shouldn’t go together, new research shows.

Rat pups.

Baby rats! Awww!
Image credits Karsten Paulick.

Researchers from the Washington State University (WSU) found that heavy cannabis exposure during pregnancy can lead to cognitive changes in the offspring of rats. Cannabis is the most commonly used illicit substance among pregnant women and may have similar effects when used by human mothers.

Pass on the puff, puff

“Prenatal exposure to cannabis may cause meaningful changes in brain development that can negatively impact cognitive functioning into adulthood,” the authors wrote in a summary of the work presented yesterday at the Society for Neuroscience’s annual meeting in San Diego.

For the study, McLaughlin — an assistant professor of Integrative Physiology and Neuroscience at the WSU — and his team exposed pregnant rats (dams) to various concentrations of cannabis vapor. This method was selected as it better recreates how people most often use the drug. The team then documented how these rats’ offspring performed in a lab test that required learning, and later adjusting, a strategy to get sugar rewards.

The vapor was administered in atmospherically controlled cages during two hour-long sessions each day. The treatment started from before pregnancy and carried until they gave birth. Rats in the control group received cannabis-free vapor, while other groups received vapor with low to high levels of cannabis. The treatment was designed to raise the rats’ blood THC levels to that of a person who has had a few puffs of the drug, the team notes.

Roughly 60 offspring of these rats were then submitted to a task similar to the Wisconsin Card Sorting Test (WCST). The WCST is a method used to test a person’s flexibility when the stimulus for positive reinforcement changes. The rats were trained to press one of two levers. These levers were tied to lights, and the rats learned that they’d receive a treat when pressing the lever close to the shining light. After this, however, the team shook things up: the reward was assigned to one of the levers permanently, regardless of which light was shining.

Cognitive changes

The rats who were exposed to cannabis in utero (in the womb) had no difficulties learning the first rule, the team reports. However, those who were exposed to higher concentrations “showed marked deficits in their ability to shift strategies when the new rule was implemented,” the researchers add.

This doesn’t mean they were unable to learn the new strategy, mind you — these rats (from dams exposed to high levels of cannabis) appeared to understand the change, as they pressed the correct lever several times in a row. But they simply wouldn’t hold to it. They would give up before striking the right lever ten times — which is what the offspring of dams exposed to less or no cannabis did.

“The general take-home message is that we see deficits, particularly in the domain of cognitive flexibility, in rats prenatally exposed to high doses of cannabis vapor,” McLaughlin said. “The impairment is not a general learning deficit, as they can learn the initial rule just fine.”

“The deficit only emerges when the learned strategy is no longer resulting in reward delivery. They cannot seem to adapt properly and tend to commit more regressive errors as a result, which suggests impairment in maintaining the new optimal strategy.”

McLaughlin cautions against jumping to conclusions, however. He says that high-exposure rats aren’t necessarily less intelligent, just less motivated. They might not be very interested in the task itself, the sugar reward, or they’d simply rather explore other activities during the test.

“They don’t have these opinions about how they need to perform because they don’t want to be perceived as ‘the stupid rat,'” he said. “Clearly that’s not what’s motivating their behavior. They’re just going to try to get as many sugar pellets as they can.”

“But at some point, do sugar pellets continue to motivate your behavior after you’ve eaten 100? Do you still care as much about them?”

The findings are still preliminary, and the team has a lot of work ahead of them. Among others, they plan to look for differences in gene expression and protein levels in the brain to determine why the rats’ behavior changed.

The findings have been presented at the Society for Neuroscience’s annual meeting Neuroscience 2018 in San Diego.

Think cats are good at keeping rats away? Think again

A new innovative study shows that cats really aren’t really very good predators of rats, and employing this strategy often backfires.

While adorable, these small felines aren’t really good at controlling rat populations — and they might end up killing other animals instead.

While cats may be the undisputed kings and queens of the internet, they weren’t always this popular — and in many parts of the world, they still aren’t. Historically, the reason why cats and humans go so well together was a very practical one: cats keep mice (and other related species away). But in the case of rats, things might not be as clear.

Despite what you may read in some media, it’s not because the rats can fight the cats off — as anyone who’s witnessed a meeting between a cat and a rat can attest, rats are woefully unprepared for the fight, while cats are supreme killing machines. They say that a desperate rat is capable of anything, and that may be true — but even when the two are comparable in size, if the cat wants to kill the rat, it can almost always do so.

The reason doesn’t have anything to do with fighting at all — but rather, with avoidance.

“Like any prey, rats overestimate the risks of predation. In the presence of cats, they adjust their behavior to make themselves less apparent and spend more time in burrows,” says the study’s lead researcher Dr. Michael H. Parsons, a visiting scholar at Fordham University. “This raises questions about whether releasing cats in the city to control rats is worth the risks cats pose to wildlife.”

“New Yorkers often boast their rats ‘aren’t afraid of anything’ and are the ‘size of a cat’,” Parsons adds. “Yet cats are commonly released to control this relatively large, defensive and potentially dangerous prey.”

He and his colleagues took advantage of a favorable situation — when feral cats invaded a New York City waste recycling center, which also hosted a hefty population of rats. They monitored the behavior and movement of microchipped rats in the presence of cats, and they also set up motion-capture video cameras to quantify the effect of the cats on the rats.

It’s the first time this has been studied in such a natural setting.

“We wanted to know whether the number of cats present would influence the number of rats observed, and vice versa,” says Parsons. “We were also interested whether the presence of cats had any effect on eight common rat behaviors or their direction of movement.”

Overall, researchers analyzed 306 videos taken over 79 days, and results were quite surprising: although a few cats were always active around the rat colony, just 20 stalking events, three kill attempts and two successful kills were recorded in this time. The two kills were when cats found rats in hiding and took them by surprise. The unsuccessful attempt was when during a chase, a cat lost interest in the rat.

Even more interesting was that the mere presence of the cats dramatically shifted the behavior of the rats. Rats spent much less time in the open, and much more time hiding.

“The presence of cats resulted in fewer rat sightings on the same or following day, while the presence of humans did not affect rat sightings,” says Parsons. In contrast, the number of rats seen on a given day did not predict the number of cats seen on the following day.

“We already knew the average weight of the rats was 330 g, much more than a typical 15 g bird or 30 g mouse,” says Parsons. “As such, we expected a low predation rate on the rats — and our study confirmed this.”

Ultimately, researchers say, it’s not that cats can’t kill rats, and even that they won’t — they absolutely can, and sometimes, will — but the conditions need to be right, and the right conditions don’t seem to happen that often. Furthermore, as Parsons underlined, using cats to keep rat populations under control seems like a flawed strategy which can easily backfire.

The reason is that while cats may not enjoy killing rats that much, they sure do enjoy killing all sorts of other wildlife, and the risks severely outweigh the advantages.

Journal Reference: Michael H. Parsons, Peter B. Banks, Michael A. Deutsch, Jason Munshi-South. Temporal and Space-Use Changes by Rats in Response to Predation by Feral Cats in an Urban Ecosystem. Frontiers in Ecology and Evolution, 2018; 6 DOI: 10.3389/fevo.2018.00146

Naked mole-rats live extremely long lives and do not age, study finds

Biology’s ‘ugly duckling’ cannot cease to amaze us. Researchers have analyzed a large trove of data on historical naked mole-rat lifespan and discovered something truly amazing. Not only do the naked mole-rats live 5 times longer than a similar-sized mammal, but they also do not show any signs of aging whatsoever.

Credits: Flickr/Tim Evanson

Naked mole-rats’ superpowers

Mole-rats are astonishing creatures. What they lack in aesthetics they make up in superpowers: they’re immune to cancer, don’t feel pain, can switch from being cold-blooded to warm-blooded, can run backward as fast as forward, and can live in extremely low oxygen conditions, their brains being capable of surviving without oxygen for up to five hours. Also, their front teeth grow out in front of their mouths.

Their behavior is even weirder. The African mole-rat, scientifically known as Heterocephalus galber, exhibits eusociality. This means that mole-rats social life is more like an ant’s than that of a typical mammal. Only the queen and one to three chosen males are fertile and are in charge of reproduction. The other members of the colony (usually consisting of almost 300 mole-rats) are in charge of food gathering, burrow security, digging tunnels, tunnel maintenance, some of them even being nannies.

If the queen dies, any other unfertile female can be crowned. The regular working mole-rat is unfertile but can turn on the reproduction function if needed. Some biologists suggest that this could be one of the reasons mole-rats live such long lives, they believe that the tiny creatures are just waiting patiently to have offsprings.

Forever young

Lead researcher Rochelle Buffenstein has studied naked mole-rats for over 30 years and has collected a huge amount data on them, including lifespan. The comparative biologist, who works for Google’s anti-aging company Calico, was completely amazed by the results. She gathered data from over 3,000 specimens from her lab and discovered that the Gompertz-Makeham law, a mathematical equation that relates aging to mortality, doesn’t apply to mole-rats.

Basically, the law says that the risk of dying rises exponentially with age; in humans, for example, it doubles roughly every 8 years after the age of 30. This theory successfully applies to most animals, especially to mammals, but apparently not to our rodent super-heroes. A naked mole-rat’s daily risk of dying is a little more than one in 10,000, even after reaching sexual maturity at 6 months, and stays the same throughout their lives, sometimes even going down a little bit more. If this isn’t unfathomable, I truly don’t know what is.

“To me this is the most exciting data I’ve ever gotten,” says Buffenstein. “It goes against everything we know in terms of mammalian biology.”

Different studies have shown that the rodent possesses certain aging-protective qualities like very active DNA repair and high levels of chaperones, which are helper proteins that support other molecules in folding correctly. Buffenstein thinks that the almost-cute animal focusses more on keeping what it already has, rather than accumulate damage.

Adding the small number of predators, high resistance to cancer and friendly behavior to the equation, we might understand why these animals have such a small risk of dying prematurely.The oldest mole-rat in captivity is 35 years old. A mouse its size lives no longer than 4 years.

But anti-aging is something else, completely. For a change, the mole-rats’ blood vessels retain their elasticity, and the queens do not enter menopause and are still able to breed even at the age of thirty.

“Our research demonstrates that naked mole rats do not age in the same manner as other mammals, and in fact show little to no signs of ageing, and their risk of death does not increase even at 25 times past their time to reproductive maturity,” Buffenstein said.

“These findings reinforce our belief that naked mole rats are exceptional animals to study to further our understanding of the biological mechanisms of longevity.”

The paper was published Jan 24, 2018, in the journal eLIFE.

Rats (Rattus Rattus) may have been wrongly acused of commiting one of the biggest mass murders in history. Credit: Pixabay.

Fleas and lice from humans, rather than rats, were likely responsible for spreading the Black Plague

It’s wasn’t rodents, but human endoparasites like fleas and lice that seem to be like the most likely carriers of the ‘Black Plague’, the horrible disease that decimated Europe throughout history.

Rats (Rattus Rattus) may have been wrongly acused of commiting one of the biggest mass murders in history. Credit: Pixabay.

Rats (Rattus Rattus) may have been wrongly accused of committing one of the biggest mass murders in history. Credit: Pixabay.

In October 1347, 12 Genovese trading ships docked at the Sicilian port of Messina after a long journey across the Black Sea. Those who greeted the ship weren’t expecting what happened next: most of the sailors aboard the ship were dead, and the few who could muster the strength to sail to safety were gravely ill.

Land lovers naturally came to their rescue, trying to treat the fever which made the sailors gravely delirious but also covered their bodies with black boils that oozed blood. They would soon regret their decision.

Within a week, the sailors were dead, and not long after most of the Messina townsfolk would come to learn first-hand what bearing this fever felt like. They wouldn’t be alone.This highly infectious disease quickly spread from Messina throughout Europe killing over 20 million people in Europe over the next five years. This was the Black Plague, and for centuries the disease would outbreak, recede, then strike again keeping Europe and Asia in a state of constant terror until the late 19th century.

The Dance of Death or Danse Macabre is an allegory on the universality of death. It’s a common painting motif in the late medieval period, heavily influenced by the collective trauma the Black Plague inflicted.

[panel style=”panel-info” title=”What is the plague? ” footer=”Credit: The WHO. “]Plague is an infectious disease caused by the bacterium Y. pestis, usually found in small mammals and their fleas.

People infected through flea bites usually develop flu-like symptoms after an incubation period of 3-7 days. Typical symptoms are the sudden onset of fever, chills, head- and body-aches and weakness, vomiting and nausea. Common antibiotics are efficient to cure plague, if they are delivered very early, because the course of the disease is usually rapid.[/panel]

The Black Plague is an infectious disease caused by the bacterium Yersinia pestis. For years, the consensus was that stowaway rats on merchant ships acted as carriers for the disease. However, recent evidence suggests that we may have been pointing the finger at the wrong guys.

Vindicating rats

Researchers at the Universities of Oslo and Ferrara compared various transmission vectors (rats, airborne, and humans) inside a contagion dissemination computer model. To everyone’s surprise, the rats-based rate of spreading was nowhere near consistent with the historical records. The airborne model also returned about the same results as the rodent-based one. Instead, in the case of human transmission, the modeled rate of spreading plague matched the facts.

So rather than fleas carried by rats, it seems more likely that fleas and lice carried by humans — all in ample amount given Middle Age hygiene — were the ones spreading Black Plague.

“While it is commonly assumed that rats and their fleas spread plague during the Second Pandemic there is little historical and archaeological support for such a claim,” the authors wrote in the Proceedings of National Academy of Science.

“Our results support that human ectoparasites were primary vectors for plague during the Second Pandemic, including the Black Death (1346–1353), ultimately challenging the assumption that plague in Europe was predominantly spread by rats.

Previously, a similar study performed by researchers in London reached the same conclusion, finding the disease spread too fast for carriers to be rats, leaving only one possible explanation – the carriers were humans.

“The evidence just isn’t there to support it,” said Barney Sloane, author of The Black Death in London. “We ought to be finding great heaps of dead rats in all the waterfront sites but they just aren’t there. And all the evidence I’ve looked at suggests the plague spread too fast for the traditional explanation of transmission by rats and fleas. It has to be person to person – there just isn’t time for the rats to be spreading it.”

Modern sanitation and public-health practices have greatly mitigated the impact of the plague but have not eliminated it. You might be surprised to hear, for instance, that 15 cases of bubonic plague were reported in the United States last year. The plague can be successfully treated with antibiotics, but only with a prompt diagnosis and treatment. Last year, the island state of Madagascar — one of the richest biodiversity hotspots on Earth –was hit by a new, devastating Bubonic plague outbreak which claimed the lives of 209 people. The death rate is 16% among patients who have been treated and between 66% and 93% among those who are not treated, according to the CDC.

Brown Rat (Rattus norvegicus). Credit: Pete Beard, Flickr.

NYC’s uptown and downtown rats don’t mix, new study found

Like all big cities around the world, New York City has a serious rat problem. But for what it’s worth, in some respects, rats can be a lot like people. According to a graduate student at Fordham University, most rats live very close to where they were born all their lives. What’s more, the researcher found significant genetic differences between uptown and downtown rats.

Brown Rat (Rattus norvegicus). Credit: Pete Beard, Flickr.

Brown Rat (Rattus norvegicus). Credit: Pete Beard, Flickr.

For the past two years, Matthew Combs has been trapping and studying brown rats (Rattus norvegicus) throughout New York City. One of his most important findings was that rats living uptown, north of 59th Street, are distinct from those living in downtown, south of 14th Street. The Midtown area is sparsely populated and mostly filled with non-residential buildings, presenting a barrier to rat genetic mixing.

“Despite the fact that rats live right in our cities and under our feet, under our noses, there’s actually quite little knowledge about how they behave in the cities, how they move around,” Combs told NPR.

“They are a serious public health threat,” he says. “They carry several zoonotic diseases that we are worried about. So the more we know about how they move, how these colonies interact, the better we can create management strategies to stop them.”

Remarkably, Combs learned that rats living in the same colony don’t venture farther than 200 to 400 meters outside their turfs. Only about one in 20 rats do venture outside the breeding grounds. These adventurous rodents may travel up to 2,000 meters away from their colony venturing into different blocks, parks or even farther. It’s these mammals — the dispersing rats — that are the most problematic. They’re the ones largely spreading diseases and genetic information.

Matt Combs (pictured) studied the DNA of 262 rats. Credit: Matt Combs.

Matt Combs (pictured) studied the DNA of 262 rats. Credit: Matt Combs.

Combs’ research took him across all parts of the city. With the help of a nifty crowd-sourced “rat map” but also old-fashioned poop tracking and garbage trailing, the young scientist ultimately studied 262 rats collected from virtually every major corner of NYC.  As he wrote in his paper published in Molecular EcologyCombs learned that Manhattan rats were similar to rats originally from Great Britain and are likely their descendant

In New York, if a person has rats, he’s solely responsible to get rid of them. But as Combs’ research suggests, it’s no one’s fault their property is infested with the pests and, secondly, if a neighbor has rats, you can bet your home has some too. So Combs hopes that his findings will change the way rats are being dealt with in NYC.

Next, Combs plans on studying genetic data on rats from Vancouver, New Orleans, and Salvador, Brazil.


Memories for opposing behaviors are stored in the same parts of the brain, study finds

The same brain region can both motivate us to undertake a learned behavior or suppress it altogether, a new study found. The results will help us better understand how our brain stores memories and how they’re called upon when needed.


Image credits Gerd Altmann / Pixabay.

While there is a general consensus that different memories are stored in different areas of the brain, there has been a lot of debate if each area can hold contradicting memories — those that control opposing behavior. For example, are the behaviors for a red or green traffic light encoded in the same area of the brain?

Pushing both ways

Questions like this one may seem a bit like nit-picking, but they’re actually really important in understanding us and our minds. Memories make us who we are. They’re also what the brain relies on to decide when and whether to take an action. So scientists are obviously keen on understanding how they work.

A new study from The Scripps Research Institute comes to answer this question. It is the first to offer proof that the same brain region can both motivate and suppress the same learned behavior.

“We behave the way we do in a specific situation because we have learned an association — a memory — tying an environmental cue to a behavior,” said Nobuyoshi Suto, TSRI Assistant Professor of Molecular and Cellular Neuroscience and co-author of the study.

“This study provides causal evidence that one brain region can store different memories.”

Suto’s work focuses on the brain structures that control motivation. For the study, he and the team trained rats to press a lever to get a reward of sugar water. After they got this down (the rats caught on pretty fast) the researchers further trained the animals to recognize two colored lights: green if the reward was available when pressing the lever, red if they would receive none. The rats quickly started adjusting their behavior after training in response to the colors. They pressed the lever more often when the green light was on, and didn’t bother with it when the red one was shining.

Based on previous electrophysiology studies, the team suspected that the mice’s brains stored both sessions of training they received in a region of the brain called the infralimbic cortex.

“We’ve seen correlational evidence, where we see brain activity together with a behavior, and we connect the dots to say it must be this brain activity causing this behavior,” said Suto.

“But such correlational evidence alone cannot establish the causality — proof that the specific brain activity is directly controlling the specific behavior.”

A weapon against addiction

The scientists then started systematically switching off specific groups of brain cells, or ‘neural ensembles’. These ensembles react to ques signaling if the reward is available or not. With the neurons inactivated, the rats didn’t perform any of the behavior encoded in the memories of those ensembles.

This proves that distinct neural ensembles in the same region of the brain directly control reward-seeking behavior or its suppression. Suto called the findings a step towards understanding how different memories are stored in the brain. He says the findings could help battle addiction by discovering which neurons are activated to motivate or prevent drug relapse.

In the future, he’d like to look at what other brain regions these infralimbic cortex neurons may be communicating with. In addition, he also would like to determine the brain chemicals mediating the promotion or suppression of reward seeking.

The full paper “Distinct memory engrams in the infralimbic cortex of rats control opposing environmental actions on a learned behavior” has been published in the journal eLife.

Rats tickled past squeaking point to identify the brain’s “tickle center”

The more ticklish among us are not alone, researchers have found. A new study on rats honed in on the mammalian brain’s “tickle center” and the effect tickling has, depending on our mood. The team also showed, for the first time, that stimulating neurons in this region results in an explosion of ultrasonic squeaks, the rat version of laughter.

Ticklish! Image credits S. Ishiyama, M. Brech (2016).

The tickling response is formed by a wide range of brain areas working in concert. One of these areas, the somatosensory cortex, was believed to be responsible for creating only the sensation of being tickled — the associated laughter was supplied, so to speak, by other parts of the brain. A new paper from the Humboldt University, Berlin (HUB) shows that electrical stimulation in this area can elicit laughter, bypassing parts of the brain traditionally considered as part of the “emotional circuitry”.

Laughing out (ultrasonically) loud

Love it or hate it, I think we all at some point reflected upon tickling. What is it, and why (the more ticklish among us cry out in anguish), why is it a thing? Even Aristotle, the famous ancient Greek philosopher and scientist, once asked why people can’t tickle themselves. But there are important reasons to understand tickling beyond satisfying our personal curiosity. One important symptom of schizophrenia, for example, is that patients can tickle themselves. Tickling is also connected to laughter, play, and the ability to feel good, notes Shimpei Ishiyama, a neuroscientist at Humboldt and lead author of a rat-tickling study looking into how our brains react to the sensation.

“Neuroscientists are so obsessed with deficits such as depression and anxiety, it’s rare to find papers about positive emotions,” he says.

Rats are good people. We’re finding more and more similarities between us and the little rodents lately. The study found that while we don’t tend to think of rats as ticklish, they not only feel, but enjoy being tickled. Previously, research has shown that the critters create ultrasonic squeaks as expressions of pleasure, squeaks which Ishiyama picked up on in his research. The rats that participated in the study returned over and over again to the designated tickling spot, and the team reports that spikes in the neurotransmitter dopamine were identified in key reward circuits of the rodents’ brains after tickling. And, just to make sure we get the message, the rats’ “joy jumped” (leaping into the air with both legs together) before or following their tickle sessions, Ishiyama explains. This behavior is a well-documented expression of positive emotions in many species, including foxes, dogs, guinea pigs, even human children.

“Although it was a very bold idea in the beginning, experiments show that rats are enjoying it,” Ishiyama says.

Ishuyama and co-author Michael Brecht, Animal Physiology/Systems Neurobiology and Neural Computation Professor at the Bernstein Center for Computational Neuroscience, HUB spent a week or two with juvenile male rats, which usually are the most playful bunch of the species, to get them used to being tickled on the back and belly. They say it’s “pretty much like” tickling cats or dogs — over time, the animals learn it’s fun to play with the human hand, recognize it as a playmate, and even start to chase it around. If that sounds adorable, it’s because it totally is. Check it out:

Once accustomed to interacting with the researchers, the team inserted electrodes into the rats’ somatosensory cortex and read their neural activity during tickling. They report increased brain activity in the cortex during the actual tickling, which isn’t very surprising, as this area responds to touches on the skin. But the activity persisted after the physical stimulus was removed, with the rodents usually chasing the hand and “giggling” even though the researchers didn’t touch the rats at this time.

The findings would go against traditionally held beliefs that this area processes only the physical sensation of tickling, by proving it also has a part to play in triggering response behaviors, Ishiyama says. To check on their conclusion, the duo then applied a small amount of current through the electrodes to stimulate the cells they’ve recorded increased activity in. This caused the rats to emit the same playful vocalizations as they had while being tickled and when chasing the researchers’ hands.

“This is very important, clear evidence that the activity of those cells is responsible for ticklishness,” Ishiyama says.

The team also determined how mood influences relationship. The team placed the rats on an elevated platform and shone bright lights on them, which would cause the nocturnal creatures to feel a lot more anxious, then tried tickling again. The rats were notably less ticklish, and the brain cells where powerful activity was recorded before remained suppressed even when stimulated with the electrodes, Ishiyama says. This suggests that there’s a really fine line between enjoying, and suffering, tickling.

“Even Darwin observed that children tickled by a stranger would rather scream than laugh,” he adds.

It’s likely that connections between neurons in the somatosensory cortex and those in other brain areas that process aspects of tickling, such as motor or socially-specialized neurons, are formed early and remain hard-wired throughout life. This interplay allows the brain to identify whether the tickler is a friend or stranger and tailor its response accordingly, the team concluded. This explanation would also explain why rats and people are more likely to enjoy tickling as adults if they experienced it during youth.

The full paper “Neural correlates of ticklishness in the rat somatosensory cortex” has been published in the journal Science.



When mice ‘sing’ they produce ultrasounds we’ve only seen in jet engines


Credit: Wikimedia Commons

To attract mates or fend off competitors, rodents such as mice and rats utter ultrasound vibrations that are inaudible to the human ear. These curious high-frequency sounds are produced using a resonance mechanism only previously seen in jet engines.

Now that’s a purr

In 2005, scientists showed that male mice ‘sing’, employing a rich repertoire. Being so small, their songs are too high for humans to hear but you can still get a glimpse if you transform the pressure waves in a lower frequency range.

A mouse song can be described in terms of syllables (a unit of sound separated from other sounds by silence) and varying pitch. A phrase may contain a sequence of syllables while a phrase type is a sequence that is repeatedly reproduced. This discovery has proven useful as a model to study human vocalization disabilities like stuttering. Unfortunately for mice, knowing this, humans have also made all sorts of gadgets that produce ultrasounds that repel the rodents.

“The mouse brain and behavior for vocal communication is not as primitive and as innate as myself and many other scientists have considered it to be,” Erich Jarvis, a neurobiologist at Duke University, explained. “Mice have more similarities in their vocal communication with humans than other species like our closest relatives,” Jarvis added, referring to chimpanzees.

Until recently, it wasn’t clear how mice are able to produce their high-pitched vocalizations. One previously proposed mechanism is similar to how a tea kettle makes whistling sounds when the water boils. Another deals with vibrations of the vocal cord. Neither of the two turned out to be correct after researchers from University of Cambridge and Washington State University studied ultra-high-speed videos of 100,000 frames per second.

The analysis suggests when mice make their love songs, the vocal folds remain completely still. Instead, a small air jet was seen coming out from the windpipe and hitting the inner wall of the larynx. This caused a characteristic resonance and ultimately produced the ultrasonic whistle, as reported in Current Biology.

“This mechanism is known only to produce sound in supersonic flow applications, such as vertical takeoff and landing with jet engines, or high-speed subsonic flows, such as jets for rapid cooling of electrical components and turbines,” said Dr Anurag Agarwal, study co-author and head of the Aero-acoustics laboratories at Cambridge’s Department of Engineering. “Mice seem to be doing something very complicated and clever to make ultrasound.”

Mice are the most common animal model used in science but despite thousands of hours of studying, the rodent still has many tricks up its sleeve. Very little is still known about how mice and rats use ultrasounds to communicate, and bats might even use this sort of mechanism as well.

For some really wicked animal tunes, check out the pied butcherbird.


Rats dream of getting to a brighter future

It’s not just us humans that dream of a better future – rats do too. When rats rest, their brains imagine a favorable future such as a tasty treat, a new study by UCL researchers found.

Image via Like Cool.

Researchers wanted to see what happens in the rats’ brain as they sleep, so they first monitored them as they looked at some delicious but inaccessible food. They then monitored them as they rested, and ultimately, as they finally received the desired food. They then did the same thing as the rats were sleeping, and found that their brains were mimicking walking to and from the desired food.

“During exploration, mammals rapidly form a map of the environment in their hippocampus,” says senior author Dr Hugo Spiers (UCL Experimental Psychology). “During sleep or rest, the hippocampus replays journeys through this map which may help strengthen the memory. It has been speculated that such replay might form the content of dreams. Whether or not rats experience this brain activity as dreams is still unclear, as we would need to ask them to be sure! Our new results show that during rest the hippocampus also constructs fragments of a future yet to happen. Because the rat and human hippocampus are similar, this may explain why patients with damage to their hippocampus struggle to imagine future events.”

The study not only revealed an amazing fact about rats, but could also help humans with damage to the hippocampus who can’t imagine the future. The hippocampus is a major component of the brains of humans and other vertebrates which plays a major role in memory and spatial navigation. But there might be more to the hippocampus than what we currently believe.

“What’s really interesting is that the hippocampus is normally thought of as being important for memory, with place cells storing details about locations you’ve visited,” explains co-lead author Dr Freyja Ólafsdóttir (UCL Biosciences). “What’s surprising here is that we see the hippocampus planning for the future, actually rehearsing totally novel journeys that the animals need to take in order to reach the food.”

Their results indicate that the hippocampus may plan routes that have not yet happened – a dream route that would lead them to the food. This is also an indication that thinking about the future is not restricted to humans – something which biologists thought for a long time.

“What we don’t know at the moment is what these neural simulations are actually for,” says co-lead author Dr Caswell Barry (UCL Biosciences). “It seems possible this process is a way of evaluating the available options to determine which is the most likely to end in reward, thinking it through if you like. We don’t know that for sure though and something we’d like to do in the future is try to establish a link between this apparent planning and what the animals do next.”


"Don't worry, buddy! I'll fix this." Image: SATO, N. ET AL., ANIMAL COGNITION (2015)

Rats rescue their friends from drowning out of empathy (and kindness)

We use the word “humane” to describe kind behavior and sympathy towards others, but the term might falsely lend some to believe that this is an exclusive human quality. Far from it. Rats too are kind, sympathetic and as “humane” as any human. For instance, when their peers are in danger of drowning, rats will come to their aid to save them. Even when a tasty treat, like chocolate, is offered instead the rat will most often than not choose to help his dying friend. To hell with chocolate!

"Don't worry, buddy! I'll fix this." Image: SATO, N. ET AL., ANIMAL COGNITION (2015)

“Don’t worry, buddy! I’ll fix this.” Image: SATO, N. ET AL., ANIMAL COGNITION (2015)

In 2011, a study led by Peggy Mason at the University of Chicago, found that when rats were trapped inside a plastic narrow tube, friends would work their way until the cage was destroyed and the trapped rat freed. The findings served as a prime example of empathy among rats, but other researchers quickly pointed out that this is not necessarily the case. The rats were merely craving companionship, they argued.

A new study, this time performed at the Kwansei Gakuin University in Japan, debunks these concerns. The researchers build an experimental compartment divided into to boxes, with a transparent wall in between. One side was flooded with water, while the other was completely dried. In each box, a rat was placed. Rats can swim, but they sure as heck don’t like water. On dry land, the rat had a lever at his disposal which he could pull to open a small, previously blocked enclosure through which the drowning rat could escape.

The researchers report in the journal Animal Cognition that the rats would regularly come to the aid of their soaked peers, and those rats who had previously experienced “the other side” (rats would swap places) were much more quick and apt at opening the enclosure. “Not only does the rat recognize distress, but he is even more moved to act because he remembers being in that situation,” the researchers note.

In the second part of the experiment, the dry rats were offered two alternatives this time: they could open the hatch for their friends or open another door that led to another small enclosure filled with chocolate. Rats love chocolate as much as they hate water. The rodents chose to help their companions instead of going for the chocolate 50% to 80% of the time. This suggests that rats often resist the urge to fill their own belies to help their friends in need. Sometimes, though. Some rats were just jerks and went for the chocolate, but so do humans. Invert chocolate with money and soaked rats with bankrupt friends. Ok, maybe not the best analogy but you get the picture.

Though we’re very much different, rats and humans have a lot in common – in terms of emotions at least. Maybe because we’re both mammals. Most importantly, the findings suggest that empathy is biologically innate, and has less to do with religion, upbringing or schooling.

“Humans are not helping purely because mom taught us to help,” Mason says for Science. “In part—and to what degree remains to be seen—we help because it’s in our biology.”


Mad snake disease makes snakes tie themselves in knots they can’t get out of


One of the oddest behavior biologists have witnessed is Inclusion Body Disease (IBD) – a fatal disease that affects captive pythons and boas causing them to tie themselves in knots they can’t untangle out of. The source of this extremely erratic and suicidal behavior was unknown until recently when researchers have found it is caused by a viral infection. Specifically, it’s a type of arenavirus that can’t be categorized in any of the two known categories of New World and Old World arenaviruses. More importantly, this is the first time scientists have found that an arenavirus can infect non-mammalian organisms.

‘This is one of the most exciting things that has happened to us in virology in a very long time,’ said snake expert Professor Michael Buchmeier, from the University of California at Irvine.

‘The fact that we have apparently identified a whole new lineage of arenaviruses that may predate the New and Old World is very exciting.’

The bizarre condition apparently has only been observed in captive snakes. It causes boas and pythons to move erratic, often as if they’re in a drunken state, and sometimes to get in a tangle they can’t escape after. Also, IBD also causes the snake to become stargazed – looking upward for long periods of time. Yup, these are some crazy snakes!

[ALSO READ] Scientists find snake no one believed existed

The researchers investigated an outbreak of IBD at the Steinhart Aquarium in San Francisco, California. After analyzing DNA samples, the researchers uncovered unusual signs that tell of the presence of a virus. Further testing revealed the virus belong to a family called arenaviruses, which typically infect rodents. It’s most likely that the snakes become infected by diseased rats on which they fed. This is the very first time  an arenavirus has been found to infect non-mammalians.

IBD was documented in a paper published in the journal mBio.




Brain to Brain interface

Rats’ brains connect to form an organic computer

In an incredible feat of neuroscience and communications, researchers at Duke University School of Medicine formed a link between pairs of rats by electronically linking their brains. As such, the rats could exchange motor and tactile information between each other. In one particular case, the experiment showed that a pair of linked rats – one rat on a continent, the other in another continent – could still effectively communicate even though they were spaced by thousands of miles from another.

Brain to Brain interface

(c) Katie Zhuang, Nicolelis Labs, Duke University

The findings offer hints to the solid possibility of developing what the researchers call “organic computers“, consisting in sharing information, either motor or tactile, between animals to solve a problem. Just recently, we reported about another breakthrough in the field, from the same Duke University scientists, after a rat was granted a sixth sense. The rat in question had its brain adapted to accept input from devices outside the body and even learn how to process invisible infrared light generated by an artificial sensor. Naturally, a puzzling question overwhelmed the researchers: if the brain can be trained to recognize information from an external sensory input, could it also be able to process information from a foreign body?

Yes it can, according to their findings. The researchers first trained pairs of rats to solve a simple problem, in which they were tasked with pressing the right lever when an indicator light above the lever switched on. If the correct action was taken the rats would be rewarded with a sip of water. With this basic info inserted, the researchers then connected the two rats’ brains  via arrays of microelectrodes inserted into the area of the cortex that processes motor information.

Here’s where the nifty part starts. One of the rats was designated as the encoder, tasked with pressing the right lever when the visual cue was on, just like in the first experiment. However, this time an electrical signal that encoded the brain activity registered during this behavior was sent directly into the brain of the second rat, the decoder. In its chamber, the decoder rat had the same levers, only with no visual cues, so therefore it would have to rely on the cues sent by the encoder rat. The decoder rat had a a maximum success rate of about 70 percent, only slightly below the possible maximum success rate of 78 percent theorized by the researchers.

It’s worth noting – to get a finer picture of just how solid the brain-to-brain interface between the two rates is – that neither of rats would receive a reward if one of them failed to press the correct lever, proving the the communication is two-way.

“We saw that when the decoder rat committed an error, the encoder basically changed both its brain function and behavior to make it easier for its partner to get it right,” said Miguel Nicolelis, M.D., PhD, lead author of the publication and professor of neurobiology at Duke University School of Medicine.

“The encoder improved the signal-to-noise ratio of its brain activity that represented the decision, so the signal became cleaner and easier to detect. And it made a quicker, cleaner decision to choose the correct lever to press. Invariably, when the encoder made those adaptations, the decoder got the right decision more often, so they both got a better reward.”

In a second set of experiments, again pair of rats were trained to distinguish between a narrow or wide opening using their whiskers and signal this by nose-pocking water ports corresponding to each opening. In this test, the  decoder had a success rate of about 65 percent, significantly above expectations.

The two rats don’t even need to be near each other – far from it. To test just how far the transmission limit of the brain-to-brain interface can stretch, the researchers  placed an encoder rat in Brazil, at the Edmond and Lily Safra International Institute of Neuroscience of Natal (ELS-IINN), and transmitted its brain signals over the Internet to a decoder rat in Durham, N.C. The two rats could still communicate between each other, even though they were on different continents.

“So, even though the animals were on different continents, with the resulting noisy transmission and signal delays, they could still communicate,” said Miguel Pais-Vieira, PhD, a postdoctoral fellow and first author of the study. “This tells us that it could be possible to create a workable, network of animal brains distributed in many different locations.”

Nicolelis added, “These experiments demonstrated the ability to establish a sophisticated, direct communication linkage between rat brains, and that the decoder brain is working as a pattern-recognition device. So basically, we are creating an organic computer that solves a puzzle.”

“But in this case, we are not inputting instructions, but rather only a signal that represents a decision made by the encoder, which is transmitted to the decoder’s brain which has to figure out how to solve the puzzle. So, we are creating a single central nervous system made up of two rat brains,” said Nicolelis. He pointed out that, in theory, such a system is not limited to a pair of brains, but instead could include a network of brains, or “brain-net.” Researchers at Duke and at the ELS-IINN are now working on experiments to link multiple animals cooperatively to solve more complex behavioral tasks.

“We cannot predict what kinds of emergent properties would appear when animals begin interacting as part of a brain-net. In theory, you could imagine that a combination of brains could provide solutions that individual brains cannot achieve by themselves,” continued Nicolelis. Such a connection might even mean that one animal would incorporate another’s sense of “self,” he said.

“In fact, our studies of the sensory cortex of the decoder rats in these experiments showed that the decoder’s brain began to represent in its tactile cortex not only its own whiskers, but the encoder rat’s whiskers, too. We detected cortical neurons that responded to both sets of whiskers, which means that the rat created a second representation of a second body on top of its own.” Basic studies of such adaptations could lead to a new field that Nicolelis calls the “neurophysiology of social interaction.”

Findings were published in the journal Scientific Reports.


Rats given ‘sixth sense’ after they recognize infrared light

infraredMost brain-machine prosthetic research today is focused on supplementing a missing sense, like medical devices that restore hearing or sight. In a novel research, however, scientists at  Duke University Medical Center have literally granted rodents a sixth sense after they implanted them with an experimental prototype that allows rats to “touch” invisible infrared light.

At first, six rats were trained to stick their snouts in one of the three holes in the side of a chamber from which light was emitted. Whenever the rat went to the correct  hole from which the light was emitted, it was rewarded with a sip of water.

Then  the researchers fitted the rats with an infrared detector connected to microscopic electrodes that were implanted in the part of their brains that processes tactile information. Then the same experiment was repeated, only this time light was replaced by infrared, which rats, like humans, can not sense inherently. It’s worth noting that this doesn’t necessary work with infrared only. According to the researchers a new degree of sensing could be achieved with other signals as well.

“We could create devices sensitive to any physical energy,” said Prof Nicolelis, from the Duke University Medical Center in Durham, North Carolina. “It could be magnetic fields, radio waves, or ultrasound. We chose infrared initially because it didn’t interfere with our electrophysiological recordings.”

In the first tries, the rats would seemingly hit holes at random, failing to sense the correct hole, since he part of their brains that normally process touch was interpreting the electrical signals for visual cues. This theory is backed by the fact that the rats scratched their faces when infrared was switched on, indicating the animals were interpreting the lights as touch.

However, after a while the rats’ behavior gradually changed, until all rants would sense the correct hole every time – remember, the sequence was always random.

“This is a very nice paper that clearly demonstrates the great potential of even the primary sensory cortex, even in a rat, to use completely new information when delivered to the cortex in electrical pulses,” says Jon Kaas, a professor of cell and developmental biology at Vanderbilt University and an expert on sensory and motor system organization. “The authors correctly see that this method of delivery can be used to replace lost sensory inputs and to provide new sensory abilities.”

If the same effects could be transferable to humans with a similar set-up, the possible prospects would be extremely interesting. Imagine being able to sense some forms of energy just as well as you fell temperature for instance, how would you interpret this new feeling?

Check out the video below that shows the rats sensing infrared.

The findings were reported in the journal Nature Communications. 

You were expecting a caption with a terminator-like rat. We couldn't find any, instead have some Jean Luc Picborg.

Cyborg-rats with artificial cerebellums – first step ahead the age of borg

Remarkably enough, scientists from Tel Aviv University in Israel, have manged to implant an artificial cerebellum in a rat’s brain, which successfully restored lost brain function. This research could provide the foundations for implementing cyborg-like functions in the human brain sometime in the distant future.

You were expecting a caption with a terminator-like rat. We couldn't find any, instead have some Jean Luc Picborg.

You were expecting a caption with a terminator-like rat. We couldn't find any, instead have some Jean Luc Picborg.

Such an advancement, could possibly one day offer the prospect of a normal life to stroke victims or other patients with other brain-related injuries or traumas. It could also maybe improve learning and memory capabilities in the old. These are all still in the realm of science fiction, though, but not for too much longer, neuroscientists hope.

Modern, high-end prosthetic limbs or ear implants communicated directly to the brain, functioning based on brain impulses. They’re truly marvelous technologies, however such devices involve only one-way communication, either from the device to the brain or vice versa.

Matti Mintz of Tel Aviv University in Israel and his colleagues have created a device that is capable of much more – a synthetic cerebellum which can receive sensory inputs from the brainstem directly. The brainstem is the posterior part of the brain, adjoining and structurally continuous with the spinal cord, that provides the main motor and sensory innervation to the face and neck via the cranial nerves.

The device developed by the Israeli scientists can interpret sensory inputs from the brainstem, and send a signal to a different region of the brainstem that prompts motor neurons to execute the appropriate movement.

“It’s proof of concept that we can record information from the brain, analyse it in a way similar to the biological network, and return it to the brain,” says Mintz, who presented the work this month at the Strategies for Engineered Negligible Senescence meeting in Cambridge, UK.

Synthesizing the brain

The team analyzed brainstem signals feeding into a real rat’s cerebellum and the output it generated in response. This information, coupled with their already complete knowledge regarding the neural architecture of the cerebellum, was used to create a digital version of the cerebellum, inside a chip which was wired to a rat’s brain using electrodes.

The chip was tested and performed remarkably. An anesthetized rat had its cerebellum disabled, before the chip was attached. While still anesthetized, scientists tried to induce a conditional motor reflex – a blink. They would spray the rat’s eye with a powder while playing a tune at the same time. This was repeated until the rat would blink only at hearing the tune alone. The scientists first tried this without the chip connected, and found the rat was unable to learn the motor reflex.

“This demonstrates how far we have come towards creating circuitry that could one day replace damaged brain areas and even enhance the power of the healthy brain,” says Francesco Sepulveda of the University of Essex in Colchester, UK, who was not involved in the research. “The circuitry mimics functionality that is very basic. Nonetheless, this is an exciting step towards enormous possibilities.”

A great challenge in face of the development of genuine cyborg-brain implants someday, however, lies in modeling larger areas of the cerebellum that can learn a sequence of movements and test the chip in a conscious animal.

“It will likely take us several decades to get there, but my bet is that specific, well-organised brain parts such as the hippocampus or the visual cortex will have synthetic correlates before the end of the century,” sais Sepulveda.

An interesting fact: Male fertility is in the bones

The researchers of the Columbia University Medical Center discovered a nice revealed a nice little nugget of information that will probably astonish most of our male (and probably female) readers. The male fertility is determined partially by the bones.

How exactly does this work and how does this effect us? Well, they’ve discovered that the skeleton in male mice acts as a regulator through a hormone released by bone, known as osteocalcin.

Until recently, the only interactions that we were aware of between the bone and the reproductive system was focused in a huge part on the influence of gonads on the build-up of bone mass.

What’s stunning however, is that although this exchange between the bone and the rate of fertility was mainly based on estrogen, researchers did not find any effect on females. When asked why, they did not elaborate on this.

“We do not know why the skeleton regulates male fertility, and not female. However, if you want to propagate the species, it’s probably easier to do this by facilitating the reproductive ability of males,”

“This is the only rationale I can think of to explain why osteocalcin regulates reproduction in male and not in female mice.” said Dr. Karsenty.

In simpler words, the researchers at the Columbia University Medical Center have no idea why this doesn’t effect females, but I suddenly feel the urge to keep my bones healthy. After all, the DNA in rats is surprisingly similar to ours.