How Dads bond with toddlers: Brain scans link oxytocin to paternal nurturing

This is the first to look at the influence of both oxytocin and vasopressin -- another hormone linked to social bonding -- on brain function in human fathers.

Credit: © pixelheadphoto / Fotolia

Study looks at neural mechanisms of paternal care giving

Fathers given boosts of the hormone oxytocin show increased activity in brain regions associated with reward and empathy when viewing photos of their toddlers, a new study finds.

"Our findings add to the evidence that fathers, and not just mothers, undergo hormonal changes that are likely to facilitate increased empathy and motivation to care for their children," says lead author James Rilling, an Emory anthropologist and director of the Laboratory for Darwinian Neuroscience. "They also suggest that oxytocin, known to play a role in social bonding, might someday be used to normalize deficits in paternal motivation, such as in men suffering from post-partum depression."

The journal Hormones and Behavior published the results of the study, the first to look at the influence of both oxytocin and vasopressin -- another hormone linked to social bonding -- on brain function in human fathers.

A growing body of literature shows that paternal involvement plays a role in reducing child mortality and morbidity, and improving social, psychological and educational outcomes. But not every father takes a "hands-on" approach to caring for his children.

"I'm interested in understanding why some fathers are more involved in caregiving than others," Rilling says. "In order to fully understand variation in caregiving behavior, we need a clear picture of the neurobiology and neural mechanisms that support the behavior."

Researchers have long known that when women go through pregnancy they experience dramatic hormonal changes that prepare them for child rearing. Oxytocin, in particular, was traditionally considered a maternal hormone since it is released into the bloodstream during labor and nursing and facilitates the processes of birth, bonding with the baby and milk production.

More recently, however, it became clear that men can also undergo hormonal changes when they become fathers, including increases in oxytocin. Evidence shows that, in fathers, oxytocin facilitates physical stimulation of infants during play as well as the ability to synchronize their emotions with their children.

In order to investigate the neural mechanisms involved in oxytocin and paternal behavior, the Rilling lab used functional Magnetic Resonance Imaging (fMRI) to compare neural activity in men with and without doses of oxytocin, administered through a nasal spray. The participants in the experiment were all healthy fathers of toddlers, between the ages of one and two. While undergoing fMRI brain scans, each participant was shown a photo of his child, a photo of a child he did not know and a photo of an adult he did not know.

When viewing an image of their offspring, participants dosed with oxytocin showed significantly increased neural activity in brain systems associated with reward and empathy, compared to placebo. This heightened activity (in the caudate nucleus, dorsal anterior cingulate and visual cortex) suggests that doses of oxytocin may augment feelings of reward and empathy in fathers, as well as their motivation to pay attention to their children.

Surprisingly, the study results did not show a significant effect of vasopressin on the neural activity of fathers, contrary to the findings of some previous studies on animals.

Research in prairie voles, which bond for life, for instance, has shown that vasopressin promotes both pair-bonding and paternal caregiving.

"It could be that evolution has arrived at different strategies for motiving paternal caregiving in different species," Rilling says.

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Prospect for more effective treatment of nerve pain

Trigeminal neuralgia: A glimmer of hope for patients – thanks to a newly tested substance.Credit: Center of Dental Medicine; UZH

Trigeminal neuralgia is characterized by sharp, lancinating pain in the teeth or facial area. The standard treatment for this chronic nerve pain can cause burdening side effects. A novel substance inhibits the pain effectively and is well tolerated, as documented by the initial results of an international study.

Trigeminal neuralgia is characterized by sharp, lancinating pain in the teeth or facial area. The standard treatment for this chronic nerve pain can cause burdening side effects. A novel substance inhibits the pain effectively and is well tolerated, as documented by the initial results of an international study involving the Center of Dental Medicine at the University of Zurich.

The sharp pain shoots to the face or teeth and seriously torments patients. Known as trigeminal neuralgia, it is one of the worst chronic nerve pains. The bouts are triggered by touch, such as shaving, putting on make-up, showering, talking and tooth brushing, or even a gust of wind. The cause is usually an irritation of the trigeminal nerve, the cranial nerve responsible for the sensory innervation of the facial area, parts of the scalp, and the oral cavity.

However, there is now a glimmer of hope for patients: Thanks to a newly tested substance, the pain can be reduced to a tolerable level, as indicated by the promising results of an international phase II study involving the Center of Dental Medicine at the University of Zurich.

Less burdening side effects

Pain signals reach the brain via the activation of sodium channels located in the membranes of nerve cells. The sodium channel "1.7" is frequently expressed on pain-conducting nerves and higher pain intensity is linked to higher channel activity. Blocking this sodium channel -- e.g. by a local anesthetic -- inhibits the pain. In trigeminal neuralgia, the nerve damage is presumed to be at the base of the skull. However, this region is hard to reach by local injections and therefore requires drug treatment.

The novel substance BIIB074 which was tested in this phase II study inhibits the sodium channel 1.7 state-dependent, meaning: The more active this sodium channel gets, the stronger it is blocked by BIIB074. By contrast, currently available medications block the sodium channel 1.7 irrespective of the nerve activity, which commonly results in burdening side effects. "Unlike conventional drugs, which often cause tiredness and concentration problems, BIIB074 was not only effective; but also very well tolerated," explains Dominik Ettlin, a dental specialist from UZH. "We will now test the new substance in a lot more subjects during the next study phase, which will reveal whether the new hope for more effective pain relief is justified," he concludes.

Trigeminal neuralgia

Around 13 people in every 100,000 are diagnosed with trigeminal neuralgia every year -- that's around 1,100 throughout Switzerland. Trigeminal neuralgia affects more women than men, the majority of whom are pensioners. Around one percent of all multiple sclerosis patients develop trigeminal neuralgia.

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When your eyes override your ears: New insights into the McGurk effect

New model shows how the brain combines information from multiple senses

Seeing is not always believing -- visual speech (mouth movements) mismatched with auditory speech (sounds) can result in the perception of an entirely different message. This mysterious illusion is known as the McGurk effect. Neuroscience researchers have created an algorithm to reveal key insight into why the brain can sometimes muddle up one of the most fundamental aspects of the human experience.

The findings will be useful in understanding patients with speech perception deficits and in building computers able to understand auditory and visual speech.

"All humans grow up listening to tens of thousands of speech examples, with the result that our brains contain a comprehensive mapping of the likelihood that any given pair of mouth movements and speech sounds go together," said Dr. Michael Beauchamp, professor of neurosurgery at Baylor College of Medicine and senior author on the paper with John Magnotti, postdoctoral research fellow at Baylor. "In everyday situations we are frequently confronted with multiple talkers emitting auditory and visual speech cues, and the brain must decide whether or not to integrate a particular combination of voice and face."

"Even though our senses are constantly bombarded with information, our brain effortlessly selects the verbal and nonverbal speech of our conversation partners from this cacophony," Magnotti said.

The McGurk effect is an example of when this goes wrong. It happens when mouth movements that are seen can override what is heard, causing a person to perceive a different sound than what is actually being said. Only when the eyes are closed, and when the sound is being heard, can the correct message be perceived. For example, the visual "ga" combined with the auditory "ba" results in the perception of "da."

Magnotti and Beauchamp were able to create an algorithm model of multisensory speech perception based on the principle of causal inference, which means given a particular pair of auditory and visual syllables, the brain calculates the likelihood they are from single versus multiple talkers and uses this likelihood to determine the final speech perception.

"We compared our model with an alternative model that is identical, except that it always integrates the available cues, meaning there is no casual inference of speech perception," said Beauchamp, who also is director of the Core for Advanced MRI at Baylor. "Using data from a large number of subjects, the model with causal inference better predicted how humans would or would not integrate audiovisual speech syllables."

"The results suggest a fundamental role for a causal inference type calculation going on in the brain during multisensory speech perception," Magnotti said.

Researchers already have an idea of how and where the brain separately encodes auditory speech and visual speech, but this algorithm shines light on the process of how they are integrated. It will serve as a guide, highlighting specific brain regions that will be essential for multisensory speech perception.

"Understanding how the brain combines information from multiple senses will provide insight into ways to improve declines in speech perception due to typical aging and even to develop devices that could enhance hearing across the life span," Beauchamp said.

(See http://openwetware.org/wiki/Beauchamp:McGurk_CI_Stimulifor examples.)

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Right-handed or left-handed: Why?

It is not the brain that determines if people are right or left-handed, but the spinal cord, new research indicates. The bio-psychologists have demonstrated that gene activity in the spinal cord is asymmetrical already in the womb.

A preference for the left or the right hand might be traced back to that asymmetry. "These results fundamentally change our understanding of the cause of hemispheric asymmetries," conclude the authors. The team report about their study in the journal eLife.

Preference in the womb

To date, it had been assumed that differences in gene activity of the right and left hemisphere might be responsible for a person's handedness. A preference for moving the left or right hand develops in the womb from the eighth week of pregnancy, according to ultrasound scans carried out in the 1980s. From the 13th week of pregnancy, unborn children prefer to suck either their right or their left thumb.

Arm and hand movements are initiated via the motor cortex in the brain. It sends a corresponding signal to the spinal cord, which in turn translates the command into a motion. The motor cortex, however, is not connected to the spinal cord from the beginning. Even before the connection forms, precursors of handedness become apparent. This is why the researchers have assumed that the cause of right respective left preference must be rooted in the spinal cord rather than in the brain.

The influence of environmental factors

The researchers analysed the gene expression in the spinal cord during the eighth to twelfth week of pregnancy and detected marked right-left differences in the eighth week -- in precisely those spinal cord segments that control the movements of arms and legs. Another study had shown that unborn children carry out asymmetric hand movements just as early as that.

The researchers, moreover, traced the cause of asymmetric gene activity. Epigenetic factors appear to be at the root of it, reflecting environmental influences. Those influences might, for example, lead to enzymes bonding methyl groups to the DNA, which in turn would affect and minimise the reading of genes. As this occurs to a different extent in the left and the right spinal cord, there is a difference to the activity of genes on both sides.

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Printable solar cells just got a little closer

The new perovskite solar cells have achieved an efficiency of 20.1 per cent and can be manufactured at low temperatures, which reduces the cost and expands the number of possible applications.

Credit: Kevin Soobrian

Research removes a key barrier to large-scale manufacture of low-cost, printable perovskite solar cells.A new innovation could make printing solar cells as easy and inexpensive as printing a newspaper. Researchers have cleared a critical manufacturing hurdle in the development of a relatively new class of solar devices called perovskite solar cells. This alternative solar technology could lead to low-cost, printable solar panels capable of turning nearly any surface into a power generator.

A U of T Engineering innovation could make printing solar cells as easy and inexpensive as printing a newspaper. Dr. Hairen Tan and his team have cleared a critical manufacturing hurdle in the development of a relatively new class of solar devices called perovskite solar cells. This alternative solar technology could lead to low-cost, printable solar panels capable of turning nearly any surface into a power generator.

"Economies of scale have greatly reduced the cost of silicon manufacturing," said Professor Ted Sargent, an expert in emerging solar technologies and the Canada Research Chair in Nanotechnology. "Perovskite solar cells can enable us to use techniques already established in the printing industry to produce solar cells at very low cost. Potentially, perovskites and silicon cells can be married to improve efficiency further, but only with advances in low-temperature processes."

Today, virtually all commercial solar cells are made from thin slices of crystalline silicon which must be processed to a very high purity. It's an energy-intensive process, requiring temperatures higher than 1,000 degrees Celsius and large amounts of hazardous solvents.

In contrast, perovskite solar cells depend on a layer of tiny crystals -- each about 1,000 times smaller than the width of a human hair -- made of low-cost, light-sensitive materials. Because the perovskite raw materials can be mixed into a liquid to form a kind of 'solar ink', they could be printed onto glass, plastic or other materials using a simple inkjet printing process.

But, until now, there's been a catch: in order to generate electricity, electrons excited by solar energy must be extracted from the crystals so they can flow through a circuit. That extraction happens in a special layer called the electron selective layer, or ESL. The difficulty of manufacturing a good ESL has been one of the key challenges holding back the development of perovskite solar cell devices.

"The most effective materials for making ESLs start as a powder and have to be baked at high temperatures, above 500 degrees Celsius," said Tan. "You can't put that on top of a sheet of flexible plastic or on a fully fabricated silicon cell -- it will just melt."

Tan and his colleagues developed a new chemical reaction than enables them to grow an ESL made of nanoparticles in solution, directly on top of the electrode. While heat is still required, the process always stays below 150 degrees C, much lower than the melting point of many plastics.

The new nanoparticles are coated with a layer of chlorine atoms, which helps them bind to the perovskite layer on top -- this strong binding allows for efficient extraction of electrons. In a paper recently published in Science, Tan and his colleagues report the efficiency of solar cells made using the new method at 20.1 per cent.

"This is the best ever reported for low-temperature processing techniques," said Tan. He adds that perovskite solar cells using the older, high-temperature method are only marginally better at 22.1 per cent, and even the best silicon solar cells can only reach 26.3 per cent.

Another advantage is stability. Many perovskite solar cells experience a severe drop in performance after only a few hours, but Tan's cells retained more than 90 per cent of their efficiency even after 500 hours of use. "I think our new technique paves the way toward solving this problem," said Tan, who undertook this work as part of a Rubicon Fellowship.

"The Toronto team's computational studies beautifully explain the role of the newly developed electron-selective layer. The work illustrates the rapidly-advancing contribution that computational materials science is making towards rational, next-generation energy devices," said Professor Alan Aspuru-Guzik, an expert on computational materials science in the Department of Chemistry and Chemical Biology at Harvard University, who was not involved in the work.

"To augment the best silicon solar cells, next-generation thin-film technologies need to be process-compatible with a finished cell. This entails modest processing temperatures such as those in the Toronto group's advance reported in Science," said Professor Luping Yu of the University of Chicago's Department of Chemistry. Yu is an expert on solution-processed solar cells and was not involved in the work.

Keeping cool during the manufacturing process opens up a world of possibilities for applications of perovskite solar cells, from smartphone covers that provide charging capabilities to solar-active tinted windows that offset building energy use. In the nearer term, Tan's technology could be used in tandem with conventional solar cells.

"With our low-temperature process, we could coat our perovskite cells directly on top of silicon without damaging the underlying material," said Tan. "If a hybrid perovskite-silicon cell can push the efficiency up to 30 per cent or higher, it makes solar power a much better economic proposition."

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Six-legged robots faster than nature-inspired gait

Researchers at EPFL and UNIL have discovered a faster and more efficient gait, never observed in nature, for six-legged robots walking on flat ground. Bio-inspired gaits -- less efficient for robots -- are used by real insects since they have adhesive pads to walk in three dimensions.

Credit: EPFL/Alain Herzog

Researchers have discovered a faster and more efficient gait, never observed in nature, for six-legged robots walking on flat ground. Bio-inspired gaits -- less efficient for robots -- are used by real insects since they have adhesive pads to walk in three dimensions. The results provide novel approaches for roboticists and new information to biologists.

When vertebrates run, their legs exhibit minimal contact with the ground. But insects are different. These six-legged creatures run fastest using a three-legged, or "tripod" gait where they have three legs on the ground at all times -- two on one side of their body and one on the other. The tripod gait has long inspired engineers who design six-legged robots, but is it necessarily the fastest and most efficient way for bio-inspired robots to move on the ground?

Researchers at EPFL and UNIL revealed that there is in fact a faster way for robots to locomote on flat ground, provided they don't have the adhesive pads used by insects to climb walls and ceilings. This suggests designers of insect-inspired robots should make a break with the tripod-gait paradigm and instead consider other possibilities including a new locomotor strategy denoted as the "bipod" gait. The researchers' findings are published inNature Communications.

The scientists carried out a host of computer simulations, tests on robots and experiments on Drosophila melanogaster -- the most commonly studied insect in biology. "We wanted to determine why insects use a tripod gait and identify whether it is, indeed, the fastest way for six-legged animals and robots to walk," said Pavan Ramdya, co-lead and corresponding author of the study.

To test the various combinations, the researchers used an evolutionary-like algorithm to optimize the walking speed of a simulated insect model based on Drosophila. Step-by-step, this algorithm sifted through many different possible gaits, eliminating the slowest and shortlisting the fastest.

Adhesive pads

The findings shed new light on problems for biologists and robotics engineers alike. The researchers found that the common insect tripod gait did emerge when they optimized their insect model to climb vertical surfaces with adhesion on the tips of its legs. By contrast, simulations of ground-walking without the adhesiveness of insects' legs revealed that bipod gaits, where only two legs are on the ground at any given time, are faster and more efficient -- although in nature no insects actually walk this way. "Our findings support the idea that insects use a tripod gait to most effectively walk on surfaces in three dimensions, and because their legs have adhesive properties. This confirms a long-standing biological hypothesis," said Ramdya. "Ground robots should therefore break free from only using the tripod gait."

Polymer boots

The researchers then built a six-legged robot capable of employing either the tripod or bipod gait. The bipod gait was again demonstrated to be faster, corroborating the simulation algorithms' results.

Finally, the experimenters examined real insects. To see if leg adhesion might also play a role in the walking coordination of real flies, they put polymer drops on the flies' legs to cover their claws and adhesive pads -- as if the flies were wearing boots -- and watched what happened. The flies quickly began to use bipod-like leg coordination similar to the one discovered in the simulation. "This result shows that, unlike most robots, animals can adapt to find new ways of walking under new circumstances," said Robin Thandiackal, a co-lead author of the study. "There is a natural dialogue between robotics and biology: Many robot designers are inspired by nature and biologists can use robots to better understand the behavior of animal species. We believe that our work represents an important contribution to the study of animal and robotic locomotion."

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Team makes planet hunting a group effort, finds more than 100 candidates

This is an artist's conceptions of the probable planet orbiting a star called GJ 411.

Credit: Courtesy of Ricardo Ramirez

An international team of astronomers released the largest-ever compilation of exoplanet-detecting observations made using a technique called the radial velocity method. They demonstrated how these observations can be used to hunt for planets by detecting more than 100 potential exoplanets, including one orbiting the fourth-closest star to our own Solar System, which is about 8.1 light years away from Earth.

The radial velocity method is one of the most successful techniques for finding and confirming planets. It takes advantage of the fact that in addition to a planet being influenced by the gravity of the star it orbits, the planet's gravity also affects the star. Astronomers are able to use sophisticated tools to detect the tiny wobble the planet induces as its gravity tugs on the star.

The virtual mountain of data released to the public in this paper was gathered as part of a two-decade radial velocity planet-hunting program that uses a spectrometer called HIRES, mounted on the 10-meter Keck-I telescope of the W.M. Keck Observatory atop Mauna Kea in Hawaii. The compilation includes almost 61,000 individual measurements made of more than 1,600 stars. By making the data public, the team is offering unprecedented access to one of the best exoplanet searches in the world.

"HIRES was not specifically optimized to do this type of exoplanet detective work, but has turned out to be a workhorse instrument of the field," said Steve Vogt of the University of California Santa Cruz, who built the instrument. "I am very happy to contribute to science that is fundamentally changing how we view ourselves in the universe."

Now as the survey moves into its third decade, the team members have decided it is time to clean house. With so much data at hand and a limited amount of time, they recognized that more exoplanets would be found by sharing their catalog with the exoplanet community.

But the team is not just giving everyone the keys to their exoplanet-finder; they are also taking it out for a spin themselves. Mikko Tuomi of the University of Hertfordshire led a sophisticated statistical analysis of the large data set to tease out the periodic signals most likely to be planets.

"We were very conservative in this paper about what counts as an exoplanet candidate and what does not," Tuomi explained, "and even with our stringent criteria, we found over 100 new likely planet candidates."

One of these probable planets is around a star called GJ 411, also known as Lalande 21185. It is the fourth-closest star to our own Sun and is only about 40 percent the mass of the Sun. The planet has a very short orbital period of just under 10 days, so it is no Earth-twin. However, the inferred [not sure about this word choice] planet, GJ 411b, continues a trend that has been seen in the overall population of detected exoplanets: the smallest planets are found around the smallest stars.

"One of our key goals in this paper is to democratize the search for planets," explained team member Greg Laughlin of Yale. "Anyone can download the velocities published on our website and use the open source Systemic software package and try fitting planets from the data. A tutorial on how to use Systemic will be available."

The team is hoping their decision will lead to a flurry of new science, as astronomers around the globe combine the HIRES data with their own existing observations, or mount new observing campaigns to follow up on potential signals. The catalog release is part of a growing trend in exoplanet science to broaden the audience and discovery space, which has emerged in part to handle the aftermath offollow-up discoveries by NASA's Kepler and K2 missions.

"I think this paper sets a precedent for how the community can collaborate on exoplanet detection and follow-up," said team-member Johanna Teske of Carnegie's Observatories and Department of Terrestrial Magnetism. "With NASA's TESS mission on the horizon, which is expected to detect 1000+ planets orbiting bright, nearby stars, exoplanet scientists will soon have a whole new pool of planets to follow up."

"The best way to advance the field and further our understanding of what these planets are made out of is to harness the abilities of a variety of precision radial velocity instruments, and deploy them in concert," added team member Jennifer Burt of MIT. "But that will require some big teams to break from tradition and start leading serious cooperative efforts."

And from Carnegie's Paul Butler, the paper's lead author and the man who helped jumpstart the field of exoplanet science: "This paper and data release represents a good chunk of my life work."

The report can be found online at:http://home.dtm.ciw.edu/ebps/wp-content/uploads/2017/02/Keck_planet_search.pdf

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