Aug 18, 2017

Archaeologists uncover ancient trading network in Vietnam

The excavation site at Rach Nui in Southern Vietnam.
A team of archaeologists from The Australian National University (ANU) has uncovered a vast trading network which operated in Vietnam from around 4,500 years ago up until around 3,000 years ago.

A new study shows a number of settlements along the Mekong Delta region of Southern Vietnam were part of a sophisticated scheme where large volumes of items were manufactured and circulated over hundreds of kilometres.

Lead researcher Dr Catherine Frieman School of the ANU School of Archaeology and Anthropology said the discovery significantly changes what was known about early Vietnamese culture.

"We knew some artefacts were being moved around but this shows evidence for a major trade network that also included specialist tool-makers and technological knowledge. It's a whole different ball game," Dr Frieman said.

"This isn't a case of people producing a couple of extra items on top of what they need. It's a major operation."

The discovery was made after Dr Frieman, an expert in ancient stone tools, was brought in to look at a collection of stone items found by researchers at a site called Rach Nui in Southern Vietnam.

Dr Frieman found a sandstone grinding stone used to make tools such as axe heads out of stone believed to come from a quarry located over 80 kilometres away in the upper reaches of the Dong Nai River valley.

"The Rach Nui region had no stone resources. So the people must have been importing the stone and working it to produce the artefacts," she said.

"People were becoming experts in stone tool making even though they live no-where near the source of any stone."

Dr Phillip Piper of the ANU School of Archaeology and Anthropology, an expert in Vietnamese archaeology, is working to map the transition from hunting and gathering to farming across Southeast Asia.

"Vietnam has an amazing archaeological record with a number of settlements and sites that provide significant information on the complex pathways from foraging to farming in the region" Dr Piper said.

"In southern Vietnam, there are numerous archaeological sites of the Neolithic period that are relatively close together, and that demonstrate considerable variation in material culture, methods of settlement construction and subsistence.

Read more at Science Daily

Mechanisms explaining positional diversity of the hindlimb in tetrapod evolution

In the snake embryo, onset of GDF11 function in the prospective vertebra region is later than in other vertebrates' embryos, resulting in a longer flank.
In the evolution of tetrapods, the position of the hindlimb has diversified along with the vertebral formula, which is the number of small bones forming the vertebra. Tetrapods, as the name implies, are species that have four feet. However, this group also includes many other animals without four or any feet, such as snakes and birds. This is because tetrapods include all the organisms, living and extinct, that descended from the last common ancestor of amphibians, reptiles and mammals, even if they have secondarily lost their "four feet."

Although researchers have long studied tetrapod anatomy, how the species-specific position of the body parts of these species -- for example, the hindlimb position along the body -- are formed in early development remains unclear. Elucidating this mystery will be a major step in evolution biology.

This crucial piece of the puzzle has finally been found by a team of researchers from Nagoya University in Japan. The researchers demonstrated that a protein called GDF11, which is involved in embryonic development, plays a vital role in the eventual position of the sacral vertebrae and the hindlimb. The study results were published in July 2017 in Nature Ecology & Evolution.

"In laboratory mice that do not produce the protein GDF11, we have noted that the sacral vertebrae and the hindlimbs are shifted more to the back," said Yoshiyuki Matsubara, researcher at the Division of Biological Science and first author of the study.

To arrive at that conclusion, the research team started by analyzing the expression pattern of the gene of interest and examining the relationship between the pattern and the prospective position of the spine and hindlimb at different development stages in chicken embryos. Next, they tested whether hindlimb positioning can be manipulated by changing the timing of GDF11 activity in the embryos. Lastly, to fully elucidate the role of GDF11 in diversification of the hindlimb position in tetrapods, the team examined the correlation between Gdf11 expression and hindlimb positioning in eight tetrapod species, including the African clawed frog, Chinese soft-shelled turtle, ocelot gecko, Japanese striped snake, chick, quail, emu and mouse.

"Our results also suggest that species-specific hindlimb positioning may have been an effect of the change in the timing or rate of events in the gene that expresses GDF11 during embryonic development," said Takayuki Suzuki, last author of the study.

According to their conclusion, snakes have a long trunk because initiation timing of Gdf11 expression in the developmental stage is much later than that in other tetrapod species.

Read more at Sience Daily

Observations of Red Supergiant Antares Shed Light on the Final Moments of Dying Stars

Antares and Scorpius
One day, our sun will become a red giant, growing so large that it will swallow Earth. That hasn't yet happened, of course, which is fortunate for us on Earth. However, it means scientists must look beyond the solar system to study the full evolutionary cycles of stars and their mechanisms at each stage.

A new study led by Keiichi Ohnaka, a researcher at Catholic University of the North in Chile, sought to understand how the distant red supergiant star Antares manages to expel so much matter off its surface as it nears the end of its life and nears its finale as a spectacular supernova.

The study demonstrated improved techniques for discovering what could be behind atmospheric motion on Antares, while showing that there are still mysteries surrounding what, exactly, causes the star's turbulent churning.

"With this study, we can open a new window to observe stars other than the sun … in a similar way that we observe the sun," Ohnaka told Space.com. "We can then apply this technique to investigate other problems — not only supergiants, like Antares, but also other types of stars and other unsolved problems."

Antares is a red supergiant star, and its large size makes it an ideal candidate for study from Earth. The star is so bright that it was given its name to mean "anti-Ares," likely because its reddish color seemed to oppose that of the shiny planet Mars, named after Ares, the ancient Greek god of war. Because it is so large, Antares is an ideal first subject for scientists to study to gain a better understanding of how stars other than Earth's sun manage to exist and function. Indeed, Antares's diameter is estimated to be 883 times larger than that of the sun. Antares is also known as Alpha Scorpii, meaning it's the brightest star in the constellation Scorpius. The red star is visible in the August night sky.

How can astronomers study distant stars? They certainly cannot travel there with today's technology: A spacecraft flying at the speed of light would take 600 years to arrive at Antares. Ohnaka's group used the European Southern Observatory's Very Large Telescope Interferometer (VLTI) in Cerro Paranal, Chile, to observe the motion of the carbon monoxide gas in Antares's atmosphere.

Until now, scientists have relied on optical and ultraviolet spectroscopy to understand stars, which means they look at light to analyze the chemical compositions of stars. That method is also used to study the sun, but has its limitations. For example, though it can indicate what a star is made of, it cannot show the mechanics of atmospheric gas movement, which could answer questions about what processes Antares experiences. The use of interferometry allows Ohnaka to capture more precise images of the outer parts of distant Antares' atmosphere, down to very small measurements of angles known as milliarseconds. According to Ohnaka, the observations his group made with VLTI's multiple telescopes over the course of five nights in April 2014 were combined to paint a detailed picture of how the gas in Antares' outer atmosphere was moving.

Ohnaka's technical use of VLTI is an important preliminary step in understanding the end stages of stars, according to John Monnier, an astronomer at the University of Michigan who was not involved in the study.

Read more at Seeker

Antimony Poisoning — Not Lead — May Have Contributed to the Roman Empire’s Fall

A section of the Anio Vetus aqueduct stands in the countryside near Tivoli, 30 kilometers out of Rome, on September 28, 2013.
Lead often takes the blame for the fall of the Roman Empire. Lead water pipes, lead cooking vessels, and lead utensils poisoned unwitting Romans, causing neurological damage, fertility disorders, and other problems — or so the story goes.

But researchers who published a study in the journal Toxicology Letters now claim the theory could be wrong.

Studying a 40-milligram fragment of an ancient lead pipe from Pompeii — the Italian city destroyed by the eruption of the volcano Mt. Vesuvius almost 2,000 year ago — the researchers discovered antimony, a chemical that’s even more toxic than lead.

Given how the inside of lead pipes calcify quickly, forming a barrier between the poisonous lead and the drinking water flowing through the pipe, antimony might have been the real culprit in bringing down one of the world’s great civilizations, said Kaare Lund Rasmussen, a study co-author and an expert in archaeological chemistry at the University of Southern Denmark.

“This is the first time that you see that it is possible they died of antimony poisoning instead of lead poisoning or both,” he said.

A grey metal-like chemical used in making lead batteries, electronics, and other products, antimony is especially common in groundwater near volcanoes, so Rasmussen said it’s crucial to look at pipes in other Roman cities. He expected Italian researchers who have the best access to Roman archeological sites would likely lead that inquiry.

“It’s only one sample,” said Rasmussen. “We know we should measure more.”

A lead pipe sample is analyzed at University of Southern Denmark.
But there’s little doubt Pompeiians were imbibing antimony that quickly causes vomiting, diarrhea, and dehydration, unlike lead poisoning that can take months or even years to develop, he said. Severe antimony poisoning can also damage the liver and kidneys and trigger cardiac arrest.

Rasmussen didn’t know how or why Pompeiians and other Romans might have kept drinking the water if it caused sickness. But he noted that today plenty of people continue to eat unhealthful foods despite health warnings even when those foods might even make them sick — think 39-cent hamburgers, fries, and strawberry shakes.

The levels of antimony in Roman water lines also might have been slight, so the casual water drinker might not have made a connection between quenching their thirst and an upset stomach, he added. “Maybe it’s not so acutely toxic,” he said. “Maybe it was just half or one-tenth of what’s lethal. Then after a while you die from it.”

Read more at Seeker

Aug 17, 2017

Astrophysicists predict Earth-like planet in star system only 16 light years away

This is the GJ832 system.
Astrophysicists at the University of Texas at Arlington have predicted that an Earth-like planet may be lurking in a star system just 16 light years away.

The team investigated the star system Gliese 832 for additional exoplanets residing between the two currently known alien worlds in this system. Their computations revealed that an additional Earth-like planet with a dynamically stable configuration may be residing at a distance ranging from 0.25 to 2.0 astronomical unit (AU) from the star.

"According to our calculations, this hypothetical alien world would probably have a mass between 1 to 15 Earth's masses," said the lead author Suman Satyal, UTA physics researcher, lecturer and laboratory supervisor. The paper is co-authored by John Griffith, UTA undergraduate student and long-time UTA physics professor Zdzislaw Musielak.

The astrophysicists published their findings this week as "Dynamics of a probable Earth-Like Planet in the GJ 832 System" in The Astrophysical Journal.

UTA Physics Chair Alexander Weiss congratulated the researchers on their work, which underscores the University's commitment to data-driven discovery within its Strategic Plan 2020: Bold Solutions | Global Impact.

"This is an important breakthrough demonstrating the possible existence of a potential new planet orbiting a star close to our own," Weiss said. "The fact that Dr. Satyal was able to demonstrate that the planet could maintain a stable orbit in the habitable zone of a red dwarf for more than 1 billion years is extremely impressive and demonstrates the world class capabilities of our department's astrophysics group."

Gliese 832 is a red dwarf and has just under half the mass and radius of our sun. The star is orbited by a giant Jupiter-like exoplanet designated Gliese 832b and by a super-Earth planet Gliese 832c. The gas giant with 0.64 Jupiter masses is orbiting the star at a distance of 3.53 AU, while the other planet is potentially a rocky world, around five times more massive than the Earth, residing very close its host star -- about 0.16 AU.

For this research, the team analyzed the simulated data with an injected Earth-mass planet on this nearby planetary system hoping to find a stable orbital configuration for the planet that may be located in a vast space between the two known planets.

Gliese 832b and Gliese 832c were discovered by the radial velocity technique, which detects variations in the velocity of the central star, due to the changing direction of the gravitational pull from an unseen exoplanet as it orbits the star. By regularly looking at the spectrum of a star -- and so, measuring its velocity -- one can see if it moves periodically due to the influence of a companion.

"We also used the integrated data from the time evolution of orbital parameters to generate the synthetic radial velocity curves of the known and the Earth-like planets in the system," said Satyal, who earned his Ph.D. in Astrophysics from UTA in 2014. "We obtained several radial velocity curves for varying masses and distances indicating a possible new middle planet," the astrophysicist noted.

For instance, if the new planet is located around 1 AU from the star, it has an upper mass limit of 10 Earth masses and a generated radial velocity signal of 1.4 meters per second. A planet with about the mass of the Earth at the same location would have radial velocity signal of only 0.14 m/s, thus much smaller and hard to detect with the current technology.

Read more at Science Daily

Four Earth-sized planets detected orbiting the nearest sun-like star

This illustration compares the four planets detected around the nearby star tau Ceti (top) and the inner planets of our solar system (bottom).
A new study by an international team of astronomers reveals that four Earth-sized planets orbit the nearest sun-like star, tau Ceti, which is about 12 light years away and visible to the naked eye. These planets have masses as low as 1.7 Earth mass, making them among the smallest planets ever detected around nearby sun-like stars. Two of them are super-Earths located in the habitable zone of the star, meaning they could support liquid surface water.

The planets were detected by observing the wobbles in the movement of tau Ceti. This required techniques sensitive enough to detect variations in the movement of the star as small as 30 centimeters per second.

"We are now finally crossing a threshold where, through very sophisticated modeling of large combined data sets from multiple independent observers, we can disentangle the noise due to stellar surface activity from the very tiny signals generated by the gravitational tugs from Earth-sized orbiting planets," said coauthor Steven Vogt, professor of astronomy and astrophysics at UC Santa Cruz.

According to lead author Fabo Feng of the University of Hertfordshire, UK, the researchers are getting tantalizingly close to the 10-centimeter-per-second limit required for detecting Earth analogs. "Our detection of such weak wobbles is a milestone in the search for Earth analogs and the understanding of the Earth's habitability through comparison with these analogs," Feng said. "We have introduced new methods to remove the noise in the data in order to reveal the weak planetary signals."

The outer two planets around tau Ceti are likely to be candidate habitable worlds, although a massive debris disc around the star probably reduces their habitability due to intensive bombardment by asteroids and comets.

The same team also investigated tau Ceti four years ago in 2013, when coauthor Mikko Tuomi of the University of Hertfordshire led an effort in developing data analysis techniques and using the star as a benchmark case. "We came up with an ingenious way of telling the difference between signals caused by planets and those caused by star's activity. We realized that we could see how star's activity differed at different wavelengths and use that information to separate this activity from signals of planets," Tuomi said.

The researchers painstakingly improved the sensitivity of their techniques and were able to rule out two of the signals the team had identified in 2013 as planets. "But no matter how we look at the star, there seem to be at least four rocky planets orbiting it," Tuomi said. "We are slowly learning to tell the difference between wobbles caused by planets and those caused by stellar active surface. This enabled us to essentially verify the existence of the two outer, potentially habitable planets in the system."

Sun-like stars are thought to be the best targets in the search for habitable Earth-like planets due to their similarity to the sun. Unlike more common smaller stars, such as the red dwarf stars Proxima Centauri and Trappist-1, they are not so faint that planets would be tidally locked, showing the same side to the star at all times. Tau Ceti is very similar to the sun in its size and brightness, and both stars host multi-planet systems.

The data were obtained by using the HARPS spectrograph (European Southern Observatory, Chile) and Keck-HIRES (W. M. Keck Observatory, Mauna Kea, Hawaii).

Read more at Science Daily

‘Euro Devil’: Fossil of carnivorous marsupial relative discovered in E Europe

Artist's impression of Anatoliadelphys maasae.
Scientists have discovered fossil remains of a new carnivorous mammal in Turkey, one of the biggest marsupial relatives ever discovered in the northern hemisphere.

The findings, by Dr Robin Beck from the University of Salford in the UK and Dr Murat Maga, of the University of Washington who discovered the fossil, are published today in the journal PLoS ONE.

The new fossil is a 43 million year old cat-sized mammal that had powerful teeth and jaws for crushing hard food, like the modern Tasmanian Devil. It is related to the pouched mammals, or marsupials, of Australia and South America, and it shows that marsupial relatives, or metatherians, were far more diverse in the northern hemisphere than previously believed.

Dr Maga found the fossil at a site near the town of Kazan, northwest of the Turkish capital, Ankara. It has been named Anatoliadelphys maasae, after the ancient name for Turkey, and Dr Mary Maas, a Turkish-American palaeontologist. The fossil is remarkably well preserved, and includes parts of the skull and most of the skeleton.

It shows that Anatoliadelphys weighed 3-4 kilograms, about the size of a domestic cat, and that it was capable of climbing. It had powerful teeth and jaws, for eating animals and possibly crushing bones. Features of the teeth and bones of Anatoliadelphys show that is closely related to marsupials, but it is not known whether it had a pouch or not.

Dr Beck, who is a world expert in the evolution of marsupials and their fossil relatives, said: "This was definitely an odd little beast -- imagine something a bit like a mini-Tasmanian devil that could climb trees.

"It could probably have eaten pretty much anything it could catch -- beetles, snails, frogs, lizards, small mammals, bones, and probably some plant material as well. This find changes what we thought we knew about the evolution of marsupial relatives in the northern hemisphere -- they were clearly a far more diverse bunch than we ever suspected."

Most fossil metatherians from the northern hemisphere were insect-eating creatures no bigger than mice or rats, whereas Anatoliadelphys was ten times larger and could have eaten vertebrate prey.

"It might seem odd to find a fossil of a marsupial relative in Turkey, but the ancestors of marsupials actually originated in the northern hemisphere, and they survived there until about 12 million years ago," said Dr Beck.

The region of Turkey where Anatoliadelphys was found was probably an island 43 million years ago, which may have enabled Anatoliadelphys to survive without competition from carnivorous placental mammals, such as fossil relatives of cats, dogs and weasels.

Read more at Science Daily

Ancient Algae Blooms May Explain the Rise of Animals on Earth

Sally-lightfoot Crabs (Grapsus grapsus) feeding on algae at low tide, Ecuador, Galapagos Islands, James Island
For nearly three billion years, the evolution of life on Earth remained mostly stalled at the single-cell stage, yielding a watery world teeming with bacteria. 

But then the melting some 650 million years ago of “Snowball Earth” — when oceans at the equator were frozen to a depth of two kilometers (1.2 miles) — led to a global algae bloom that changed everything, researchers reported Wednesday.

"Microscopic bacteria were replaced by much larger algae" fed by nutrients ripped from mountainsides as glaciers slid toward the sea, said Jochen Brocks, a professor at Australian National University and lead author of a study published in Nature.

"These organisms revolutionized the base of the food web and, without them, we would not be here today," he told AFP while attending an international geochemistry conference in Paris, where he presented his findings.

When and why animals first appeared on the planet has been one of the great, and most durable, mysteries in science.

Up to now, there have been more theories than hard facts, with experts divided into two main camps on the origin of complex organisms, said Brocks, whose own findings pushed him from one camp to the other.

"The fight has been going on for two decades," he said by phone. "I was just in a session at the conference, and they are really butting heads."

One side, populated mainly by biologists, contends there is really no puzzle to be solved — the evolution of something as intricate as an animal genome takes time, even billions of years, they argue. The constraints, in other words, were intrinsic and not environmental.

"The second camp says that animals could have evolved more quickly, but that something was holding them back," Brocks said.

Insufficient oxygen has long been seen as a crucial barrier to the rise of multi-cellular life. Large, energy-consuming organisms need a powerful fuel — and the oxygen to help burn it.

Brocks's research also supports a bottleneck hypothesis, but points in a different direction.

Coincidence 'very unlikely'

"Our study presents the first real evidence that it was not oxygen that was lacking, but an abundant, nutritious food source," he said.  

Which brings us back to algae.

Vast amounts of nitrogen-rich nutrients tumbled into the sea as Earth's surface melted, allowing photosynthesizing algae to proliferate at the expense of far-smaller bacteria.

The bottom of the food chain determines how much energy is in the ecosystem, and algae are on average 1,000 times bigger than bacteria.

"Proportionally, it is the difference between a mouse to an elephant — in ocean ecology, size is all that really matters," Brocks said.

"You suddenly had a huge amount of nutritious, high-energy particles at the base of the food web that then drives the entire ecosystem towards complex, large creatures."

Read more at Seeker

Aug 16, 2017

Boron nitride foam soaks up carbon dioxide

A microscope image shows the high surface area of hexagonal-boron nitride foam glued together with polyvinyl alcohol. The tough, light foam can be used to soak up carbon dioxide or as a material to shield biological tissues from lasers.
Rice University materials scientists have created a light foam from two-dimensional sheets of hexagonal-boron nitride (h-BN) that absorbs carbon dioxide.

They discovered freeze-drying h-BN turned it into a macro-scale foam that disintegrates in liquids. But adding a bit of polyvinyl alcohol (PVA) into the mix transformed it into a far more robust and useful material.

The foam is highly porous and its properties can be tuned for use in air filters and as gas absorption materials, according to researchers in the Rice lab of materials scientist Pulickel Ajayan.

Their work appears in the American Chemical Society journal ACS Nano.

The polyvinyl alcohol serves as a glue. Mixed into a solution with flakes of h-BN, it binds the junctions as the microscopic sheets arrange themselves into a lattice when freeze-dried. The one-step process is scalable, the researchers said.

"Even a very small amount of PVA works," said co-author and Rice postdoctoral researcher Chandra Sekhar Tiwary. "It helps make the foam stiff by gluing the interconnects between the h-BN sheets -- and at the same time, it hardly changes the surface area at all."

In molecular dynamics simulations, the foam adsorbed 340 percent of its own weight in carbon dioxide. The greenhouse gas can be evaporated out of the material, which can be reused repeatedly, Tiwary said. Compression tests showed the foam got stiffer through 2,000 cycles as well.

And when coated with PDMS, another polymer, the foam becomes an effective shield from lasers that could be used in biomedical, electronics and other applications, he said.

Ultimately, the researchers want to gain control over the size of the material's pores for specific applications, like separating oil from water. Simulations carried out by co-author Cristiano Woellner, a joint postdoctoral researcher at Rice and the State University of Campinas, Brazil, could serve as a guide for experimentalists.

"It's important to join experiments and theoretical calculations to see the mechanical response of this composite," Woellner said. "This way, experimentalists will see in advance how they can improve the system."

Rice graduate student Peter Owuor is lead author of the paper. Co-authors are Ok-Kyung Park, a visiting scholar at Rice and a postdoctoral researcher at Chonbuk National University, Republic of Korea; Rice postdoctoral researchers Almaz Jalilov and Rodrigo Villegas Salvatierra and graduate students Luong Xuan Duy, Sandhya Susarla and Jarin Joyner; Rice alumnus Sehmus Ozden, now a postdoctoral fellow at Los Alamos National Laboratory; Robert Vajtai, a senior faculty fellow at Rice; Jun Lou, a Rice professor of materials science and nanoengineering; and James Tour, Rice's T.T. and W.F. Chao Chair in Chemistry as well as a professor of computer science and of materials science and nanoengineering; and Professor Douglas Galv√£o of the State University of Campinas. Ajayan is chair of Rice's Department of Materials Science and NanoEngineering, the Benjamin M. and Mary Greenwood Anderson Professor in Engineering and a professor of chemistry.

Read more at Science Daily

Scientists use magnetic fields to remotely stimulate brain -- and control body movements

Scientists have used magnetic nanoparticles to stimulate neurons deep in the brain to evoke body movements of mice. This image shows a section of a mouse brain with injected magnetic nanoparticles (colored red) covering targeted cells in the striatum.
Scientists have used magnetism to activate tiny groups of cells in the brain, inducing bodily movements that include running, rotating and losing control of the extremities -- an achievement that could lead to advances in studying and treating neurological disease.

The technique researchers developed is called magneto-thermal stimulation. It gives neuroscientists a powerful new tool: a remote, minimally invasive way to trigger activity deep inside the brain, turning specific cells on and off to study how these changes affect physiology.

"There is a lot of work being done now to map the neuronal circuits that control behavior and emotions," says lead researcher Arnd Pralle, PhD, a professor of physics in the University at Buffalo College of Arts and Sciences. "How is the computer of our mind working? The technique we have developed could aid this effort greatly."

Understanding how the brain works -- how different parts of the organ communicate with one another and control behavior -- is key to developing therapies for diseases that involve the injury or malfunction of specific sets of neurons. Traumatic brain injuries, Parkinson's disease, dystonia and peripheral paralysis all fall into this category.

The advances reported by Pralle's team could also aid scientists seeking to treat ailments such as depression and epilepsy directly through brain stimulation.

The study, which was done on mice, was published Aug. 15 in eLife, an open-source, peer-review journal. Pralle's team included first authors Rahul Munshi, a UB PhD candidate in physics, and Shahnaz Qadri, PhD, a UB postdoctoral researcher, along with researchers from UB, Philipps University of Marburg in Germany and the Universidad de Santiago de Compostela in Spain.

Magneto-thermal stimulation involves using magnetic nanoparticles to stimulate neurons outfitted with temperature-sensitive ion channels. The brain cells fire when the nanoparticles are heated by an external magnetic field, causing the channels to open.

Targeting highly specific brain regions

In mice, Pralle's team succeeded in activating three distinct regions of the brain to induce specific motor functions.

Stimulating cells in the motor cortex caused the animals to run, while stimulating cells in the striatum caused the animals to turn around. When the scientists activated a deeper region of the brain, the mice froze, unable to move their extremities.

"Using our method, we can target a very small group of cells, an area about 100 micrometers across, which is about the width of a human hair," Pralle says.

How magneto-thermal stimulation works

Magneto-thermal stimulation enables researchers to use heated, magnetic nanoparticles to activate individual neurons inside the brain.

Here's how it works: First, scientists use genetic engineering to introduce a special strand of DNA into targeted neurons, causing these cells to produce a heat-activated ion channel. Then, researchers inject specially crafted magnetic nanoparticles into the same area of the brain. These nanoparticles latch onto the surface of the targeted neurons, forming a thin covering like the skin of an onion.

When an alternating magnetic field is applied to the brain, it causes the nanoparticles' magnetization to flip rapidly, generating heat that warms the targeted cells. This forces the temperature-sensitive ion channels to open, spurring the neurons to fire.

The particles the researchers used in the new eLife study consisted of a cobalt-ferrite core surrounded by a manganese-ferrite shell.

An advance over other methods, like optogenetics


Pralle has been working to advance magneto-thermal stimulation for about a decade. He previously demonstrated the technique's utility in activating neurons in a petri dish, and then in controlling the behavior of C. elegans, a tiny nematode.

Pralle says magneto-thermal stimulation has some benefits over other methods of deep-brain stimulation.

One of the best-known techniques, optogenetics, uses light instead of magnetism and heat to activate cells. But optogenetics typically requires implantation of tiny fiber optic cables in the brain, whereas magneto-thermal stimulation is done remotely, which is less invasive, Pralle says. He adds that even after the brains of mice were stimulated several times, targeted neurons showed no signs of damage.

Read more at Science Daily