Can rats read minds? Perhaps not usually, but researchers at Duke University have developed what they call a brain-to-brain interface, which transfers information directly from one rat’s brain to another. The interface allows the decisions of a rat on one continent to control the behaviors of a rat on another.
To accomplish this, researchers in North Carolina implanted tiny electrodes into the brain of a rat to record its activity, and then trained the rat to distinguish between a wide chute and a narrow one by whisker feel. The rat had to correctly match the sensation (wide or narrow) with a corresponding hole (left or right) by poking it with its nose. When the rat correctly matched the width and hole, which it did 96 percent of the time, the rat was rewarded with a drink of water. Researchers called this rat the encoder.
Petting feels good. You can see it in a cat’s slowly closing eyes or the contented panting of a dog getting his belly rubbed. In fact, all mammals enjoy being caressed, including humans. Researchers looked at this phenomenon in lab mice and found that stroking stimulates a very specific set of neurons that have to do with hair.
Some sensory neurons are relatively non-discriminatory. They respond to touch, temperature and pretty much anything that comes into contact with the skin. A few years back, researchers identified a rare type of neuron called MRGPRB4+, which is linked specifically to hair follicles. In lab tests on a patch of mouse skin, these neurons didn’t respond to a single stimulus. But with live mice the researchers got much more promising results, published in Nature on Wednesday.
A burrow is just a hole in the ground, right? Wrong. Different species of mice have very different burrow designs, and
a new study suggests that a mouse’s architectural know-how is written in its DNA: Mice constructed these species-specific burrows even when they had never seen one before.
Researchers examined the burrowing behaviors of two related mouse species. The deer mouse makes a simple burrow, just a short tunnel that leads to a nest. The closely related oldfield mouse puts a little more feng shui in its design, extending the entry tunnel and adding a back door for quick escapes from the nest. To see if the blueprints for these burrow designs were based on instinct, researchers brought the mice into the lab.
Our cognitive abilities tend to decline when we get older, as we have trouble remembering old facts and skills and learning new ones. But a little young blood reverses some ill effects of old age, at least in mice, researchers reported at the Society for Neuroscience conference last week.
Neuroscientist Saul Villeda and his team gave elderly mice infusions of blood from younger, sprightlier members of their species. The old mice fortified with young blood improved on learning and memory tasks, such as finding a platform submerged in water and getting conditioned (think Pavlov’s dogs) to fear situations associated with electric shocks.
Our ability to see depends on two factors: light-sensitive rods and cones in the retina, and the nerves that transmit signals from these cells to the brain (along with the brain itself, of course). When the rods and cones die, which can occur as the eye ages or in the retina-damaging eye disease retinitis pigmentosa, the nerves can sometimes still function—if they have a new, working sensor for light. To replace the rods and cones, previous treatments have used electronic implants, which require surgery, or gene therapy, which relies on injections deep into the eye. But in a new technique, all it takes to restore vision—at least partially—is a much less invasive injection of the chemical AAQ.
Just as Vikings pillaged their way from Norway to Greenland and Iceland 1000 years ago, another group of furry raiders appears to have made a similar trek: common house mice. A new analysis of ancient and modern mouse DNA suggests that the mice in Iceland and Greenland came from Norway.
Scientists began by looking at mitochondrial DNA (mtDNA) extracted from living mice in Iceland and Greenland as well as from mouse bones found in old settlements. The ancient gene sequences were strikingly similar to those of modern mice found in UK and Norway, as well as to modern Icelandic mice, suggesting a common origin in either the UK or Norway. The low genetic diversity in Iceland, to boot, suggests recent colonization by a small number of stowaway mice. These findings have prompted speculation that mice may have arrived in the islands in Viking ships, though there is no evidence that that’s the case.
As scientists continue using human DNA to map our ancestors’ migrations, it’s neat to be reminded that there might be similar patterns of migration in species that tend to live with humans. Perhaps the bones of mice may in the future provide helpful clues for figuring out where ancient humans went and what they brought with them.
[via New Scientist]
Creatures as large as elephants are unusual; it takes a long time to evolve such size.
How long does it take for a mammal as small as a mouse to evolve into something as large as an elephant? A really, really long time, a recent study has found: about 24 million generations, at minimum.
To get that number, researchers looked at the evolution of body mass over the last 70 million years, after the dinosaurs went extinct and surviving animals expanded into the ecological niches they left behind. That estimate is far longer than earlier estimates, which, extrapolating from bursts of super-fast evolution in mice, range from just 200,000 to 2 million generations. Such speedy evolution, in actuality, is probably not sustainable over the long term—hence the lengthy new estimate.
Cardiomyocytes damaged by a heart attack
What’s the News: Scientists are devoting countless research hours to treatments based on embryonic stem cells, differentiating these blank-slate cells from embryos into brain cells, light-sensing retinal cells, blood cells, and more to replace damaged or destroyed tissues in the body. Now, a new study in mice shows such that nature has arrived at just such a solution, too: When a pregnant mouse has a heart attack, her fetus donates some of its stem cells to help rebuild the damaged heart tissue.
What’s the News: While mice are a major tool for biomedical research, they’re not always useful for testing the toxicity of pharmaceutical drugs because their livers don’t react to drugs the same way that human livers do. But in a new study, published in the journal PNAS, scientists at MIT have gotten around this issue by implanting mice with miniature, humanized livers. Researchers may be able to use the artificial organs to help create drugs for diseases like hepatitis C, which mice don’t normally contract, and improve the development of other drugs. “In the near term, we envision using these mice alongside existing toxicology models to help make the drug development pipeline safer and more efficient,” said MIT biomedical engineer Alice Chen (via LiveScience).
What’s the News: In the animal kingdom, prey species must follow one rule above all others: keep away from predators. To do this, some animals take chemical cues from the urine they stumble upon. Now, new research published in the Proceedings of the National Academy of Science has identified a single molecule in the urine of many mammalian carnivores that causes rodents to scurry in fear. This chemical could eventually help scientists understand instinctual behavior in animals.