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  • Why Is Yawning Contagious

    Why Is Yawning Contagious

    Someone starts and it spreads…why is yawning contagious?

    Whether at work, school or a dinner, once someone yawns, it is over…more yawning, then someone gets up and the fun bubble has popped.  But what happens? Why is yawning contagious? In 400 B.C., Hippocrates thought yawning removed bad air from the lungs before a fever. In the 17th and 18th century, doctors believed yawning increased oxygen in the blood, blood pressure, heart rate and blood flow itself. So it made sense you would want to follow the example…but what makes the body do it involuntary?

    In the past, people have had many hypotheses. In the last century, consensus moved toward the idea that yawning cools down the brain, so when ambient conditions and temperature of the brain itself increase, yawning episodes increase.

    Typically a yawn lasts four to seven seconds and happens in fits of two or three. It involves the following steps:

    • A long inhale (breathing in) using your nose and then mouth.
    • A brief episode of powerful muscle stretching around your mouth and throat.
    • A rapid exhale (breathing out) using your mouth with muscle tension release.

    Yawning is mostly involuntary, meaning you don’t have control over it. And most scientists consider it a reflex.

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    And yawning occurs in just about every species. It happens when an animal is tired. It can be used as a threat display in some species. Yawning can occur during times of social conflict and stress, something researchers call a displacement behavior.  So it isn’t just a human reaction, it is the animal kingdom also….so why does it happen and why is so darn contagious?

    Yawning happens in many animal species – and seems to pass from one to another. Robert Gramner on Unsplash, CC BY

    Yawning is a common but perplexing human function. Scientists have several theories but nothing concrete. Common triggers of yawning include tiredness, boredom, waking up and stress.  A current theory about yawning is the arousal hypothesis states yawning activates your brain. This theory is tied to the fact tiredness and boredom tend to trigger yawning the most.

    Seeing or hearing other people yawn can also cause you to yawn. The wide-open mouth can be contagious, especially in social species such as humans, chimpanzees, bonobos, macaques and wolves. In addition, research on humans tell us people who are more empathetic tend to be more susceptible to contagious yawning. When you see someone else yawn, the networks in your brain responsible for empathy and social skills are activated.

    Is yawning contagious for dogs also. In U.K. biologists tested for contagious yawning between people and man’s best friend. Although 5 of the 19 dogs studied did yawn in response to an unfamiliar person’s yawn, the researchers couldn’t prove the yawns were contagious.  But, cognitive and behavioral scientists at the University of Tokyo once again tested contagious yawning in canines while controlling for stress. This time researchers found dogs were more likely to yawn in response to a familiar person. They concluded dogs can “catch” a yawn from humans and yawning is a social rather than an stress-based behavior.

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    University of Nebraska psychologists looked at contagious yawning in shelter dogs. They found some dogs yawned when exposed to human yawning and had elevated cortisol levels, a proxy for stress. Levels of the cortisol stress hormone did not rise in dogs who didn’t yawn in response to a human yawn. This finding suggests some dogs find human yawning stressful and others do not. More research is needed to evaluate this aspect of the human-dog relationship.The ConversationThe jury’s still out on the true why of yawning. But when it comes to inter-species yawning, collect your own anecdotal data. Try an experiment at home, yawn and see if your pet yawns back.

    Anthony Washington

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  • Imaging tech: No longer a last resort

    Imaging tech: No longer a last resort

    Newswise — There are various ways to image biological samples on a microscopic level, and each has its own pros and cons. For the first time, a team of researchers, including those from the University of Tokyo, has combined aspects from two of the leading imaging techniques to craft a new method of imaging and analyzing biological samples. Its concept, known as RESORT, paves the way to observe living systems in unprecedented detail.

    For as long as humanity has been able to manipulate glass, we have used optical devices to peer at the microscopic world in ever increasing detail. The more we can see, the more we can understand, hence the pressure to improve upon tools we use to explore the world around, and inside, us. Contemporary microscopic imaging techniques go far beyond what traditional microscopes can offer. Two leading technologies are super-resolution fluorescence imaging, which offers good spatial resolution, and vibrational imaging, which compromises spatial resolution but can use a broad range of colors to help label many kinds of constituents in cells.

    “We were motivated by the limitations of these kinds of imaging techniques to try and create something better, and with RESORT we are confident that we have achieved this,” said Professor Yasuyuki Ozeki from the University of Tokyo’s Research Center for Advanced Science and Technology. “RESORT stands for reversible saturable optical Raman transitions, and it combines the benefits of super-resolution fluorescence and vibrational imaging without inheriting the detriments of either. It is a laser-based technique that uses something known as Raman scattering, a special interaction between molecules and light which helps identify what’s in a sample under the microscope. We successfully performed RESORT imaging of mitochondria in cells to validate the technique.”

    There are several stages to RESORT imaging, and although it might seem complicated, the setup is less complicated than that of the techniques it’s aiming to replace. Firstly, the specific components of the sample to be imaged need to be labeled, or stained, with special chemicals called photoswitchable Raman probes, whose Raman scattering can be controlled by the different kinds of laser light employed by RESORT. Next, the sample is placed within an optical apparatus used to correctly illuminate the sample and build an image of it. For that to occur, the sample is then irradiated with two-color infrared laser pulses for detecting Raman scattering, ultraviolet light and a special donut-shaped beam of visible light. Together, these constrain the area where Raman scattering can occur, which means the final stage, imaging, can detect the probe at the very precise point, which leads to a high spatial resolution.

    “It’s not just about gaining higher-resolution images of microscopic samples; after all, electron microscopes can image these things in far greater detail,” said Ozeki. “However, electron microscopes necessarily damage or impede the samples they observe. Through the future development adding more colors to the palette of Raman probes, RESORT will be able to image many components in living samples in action to analyze complex interactions like never before. This will contribute to a deeper understanding of fundamental biological processes, disease mechanisms and potential therapeutic interventions.”

    The team’s main aim was to improve microscopic imaging for use in the medical research field and related areas. But the advancements it has made in the design of the laser could be used in other laser applications as well, where high power or precise control is required, such as materials science.
     

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    University of Tokyo

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  • Accurate measurements of black carbon in the atmosphere

    Accurate measurements of black carbon in the atmosphere

    Newswise — Our industrialized society releases many and various pollutants into the world. Combustion in particular produces aerosol mass including black carbon. Although this only accounts for a few percent of aerosol particles, black carbon is especially problematic due to its ability to absorb heat and impede the heat reflection capabilities of surfaces such as snow. So, it’s essential to know how black carbon interacts with sunlight. Researchers have quantified the refractive index of black carbon to the most accurate degree yet which might impact climate models.

    There are many factors driving climate change; some are very familiar, such as carbon dioxide emissions from burning fossil fuels, sulfur dioxide from cement manufacture or methane emissions from animal agriculture. Black carbon aerosol particles, also from combustion, are less covered in the news but are particularly important. Essentially soot, black carbon is very good at absorbing heat from sunlight and storing it, adding to atmospheric heat. At the same time, given dark colors are less effective at reflecting light and therefore heat, as black carbon covers lighter surfaces including snow, it reduces the potential of those surfaces to reflect heat back into space.

    “Understanding the interaction between black carbon and sunlight is of fundamental importance in climate research,” said Assistant Professor Nobuhiro Moteki from the Department of Earth and Planetary Science at the University of Tokyo. “The most critical property of black carbon in this regard is its refractive index, basically how it redirects and disperses incoming light rays. However, existing measurements of black carbon’s refractive index were inaccurate. My team and I undertook detailed experiments to improve this. With our improved measurements, we now estimate that current climate models may be underestimating the absorption of solar radiation due to black carbon by a significant 16%.”

    Previous measurements of the optical properties of black carbon were often confounded by factors such as lack of pure samples, or difficulties in measuring light interactions with particles of differing complex shapes. Moteki and his team improved this situation by capturing the black carbon particles in water, then isolating them with sulfates or other water-soluble chemicals. By isolating the particles, the team was better able to shine light on them and analyze the way they scatter, which gave researchers the data to calculate the value of refractive index.

    “We measured the amplitude, or strength, and phase, or step, of the light scattered from black carbon samples isolated in water,” said Moteki. “This allowed us to calculate what is known as the complex refractive index of black carbon. Complex because rather than being a single number, it’s a value that contains two parts, one of which is ‘imaginary’ (concerned with absorption), though its impact is very, very real. Such complex numbers with imaginary components are actually very common in the field of optical science and beyond.”

    As the new optical measurements of black carbon imply that current climate models are underestimating its contribution to atmospheric warming, the team hopes that other climate researchers and policymakers can make use of their findings. The method developed by the team to ascertain the complex refractive index of particles can be applied to materials other than black carbon. This allows for the optical identification of unknown particles in the atmosphere, ocean or ice cores, and the evaluation of optical properties of powdered materials, not just those related to the ongoing problem of climate change.

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    Journal article: Nobuhiro Moteki, Sho Ohata, Atsushi Yoshida & Kouji Adachi. “Constraining the complex refractive index of black carbon particles using the complex forward-scattering amplitude”, Aerosol Science and Technology. DOI: 10.1080/02786826.2023.2202243

    Funding:
    Funds were provided by the Environment Research and Technology Development Fund (JPMEERF20202003) of the Environmental Restoration and Conservation Agency, the Japan Society for the Promotion of Science (JSPS) KAKENHI program (JP19H04236, JP19KK0289, Accepted Manuscript JP19H04259, JP19H05699, 22H03722, and 22H01294), and the Arctic Challenge for Sustainability ArCS II project (JPMXD1420318865) of the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan.

    Useful links:
    Graduate School of Science – https://www.s.u-tokyo.ac.jp/en/
    Department of Earth and Planetary Science – https://www.eps.s.u-tokyo.ac.jp/en/

    About The University of Tokyo
    The University of Tokyo is Japan’s leading university and one of the world’s top research universities. The vast research output of some 6,000 researchers is published in the world’s top journals across the arts and sciences. Our vibrant student body of around 15,000 undergraduate and 15,000 graduate students includes over 4,000 international students. Find out more at www.u-tokyo.ac.jp/en/ or follow us on Twitter at @UTokyo_News_en.

    University of Tokyo

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  • Honey Bee Brains: A Look at Evolution

    Honey Bee Brains: A Look at Evolution

    Newswise — Researchers have proposed a new model for the evolution of higher brain functions and behaviors in the Hymenoptera order of insects. The team compared the Kenyon cells, a type of neuronal cell, in the mushroom bodies (a part of the insect brain involved in learning, memory and sensory integration) of “primitive” sawflies and sophisticated honey bees. They found that three diverse, specialized Kenyon cell subtypes in honey bee brains appear to have evolved from a single, multifunctional Kenyon cell-subtype ancestor. In the future, this research could help us better understand the evolution of some of our own higher brain functions and behaviors.

    Are you “busy as a bee,” a “social butterfly” or a “fly on the wall”? There are many ways we compare our behavior to that of insects, and as it turns out there may be more to it than just fun idioms. Studying insects could help us understand not only how their behavior has evolved, but also the behavior of highly evolved animals, including ourselves. Mammalian brains are big and complex, so it is difficult to identify which behaviors and neural and genetic changes have co-developed over time. By comparison, insect brains are much smaller and simpler, making them useful models for study.

    “In 2017, we reported that the complexity of Kenyon cell (KC) subtypes in mushroom bodies in insect brains increases with the behavioral diversification in Hymenoptera (a large and varied order of insects)” explained Professor Takeo Kubo from the Graduate School of Science at the University of Tokyo and co-author of the current study. “In other words, the more KC subtypes an insect has, the more complex its brain and the behaviors it may exhibit. But we didn’t know how these different subtypes evolved. That was the stimulus for this new study.”

    The team from the University of Tokyo and Japan’s National Agriculture and Food Research Organization (NARO) chose two Hymenoptera species as representatives for different behaviors: the solitary turnip sawfly (which has a single KC subtype) and the sophisticated, social honey bee (which has three KC subtypes). As the sawfly has a more “primitive” brain, it is thought to contain some ancestral properties of the honey bee brain. To uncover the potential evolutionary pathways between them, the researchers used transcriptome analysis to identify the gene expression profiles (the genetic activity) of the various KC subtypes and speculate their functions.

    “I was surprised that each of the three KC subtypes in the honey bee showed comparable similarity to the single KC type in the sawfly,” said Assistant Professor Hiroki Kohno, co-author from the Graduate School of Science.  “Based on our initial comparative analysis of several genes, we had previously supposed that additional KC subtypes had been added one by one. However, they appear to have been separated from a multifunctional ancestral type, through functional segregation and specialization.” As the number of KC subtypes increased, each subtype almost equally inherited some distinct properties from an ancestral KC. These then modified in different ways, resulting in their varied present-day functions.

    The researchers wanted a specific behavioral example of how ancestral KC functions are present in both the sawfly and the honey bee. So, they trained sawflies to engage in a common honey bee behavior test, where they learn to associate an odor stimulus with a reward. Although challenging at first, the team was eventually able to engage the sawflies in the memory task. The researchers then manipulated a gene called CaMKII in sawfly larvae, which in honey bees is associated with forming long-term memory, a KC function. When the larvae became adults, their long-term memory was impaired, indicating that the gene plays a similar role in both sawflies and honey bees. Although CaMKII was expressed (i.e., was active) across the entire single KC subtype in sawflies, in honey bees, it was preferentially expressed in only one KC subtype. This suggests that the role of CaMKII in long-term memory was passed down to the specific KC subtype in the honey bee.

    Despite differences in the size and complexity of insect and mammalian brains, there are commonalities in terms of function and the basic architecture of the nervous system. That is why the model proposed in this study for the evolution and diversification of KC subtypes may help towards better understanding the evolution of our own behavior. Next, the team is interested in studying KC types acquired in parallel with social behaviors, such as the honey bee’s “waggle dance.”

    “We would like to clarify whether the model presented here is applicable to the evolution of other behaviors,” said Takayoshi Kuwabara, doctoral student and lead author from the Graduate School of Science. “There are many mysteries about the neural basis that controls social behavior, whether in insects, animals or humans. How it has evolved still remains largely unknown. I believe that this study is a pioneering work in this field.”

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    Paper Title:

    Takayoshi Kuwabara, Hiroki Kohno, Masatsugu Hatakeyama, Takeo Kubo. Evolutionary dynamics of mushroom body Kenyon cell types in hymenopteran brains from multi-functional type to functionally specialized types. Science Advances. DOI: 10.1126/sciadv.add4201

    Funding:

    This research was supported by Grant-in-Aid for Scientific Research (B) 20H03300 (TKubo) and Grant-in-Aid for JSPS Fellows 21J20847 (TKuwabara).

    University of Tokyo

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  • Rats bop to the beat

    Rats bop to the beat

    Newswise — Accurately moving to a musical beat was thought to be a skill innately unique to humans. However, new research now shows that rats also have this ability. The optimal tempo for nodding along was found to depend on the time constant in the brain (the speed at which our brains can respond to something), which is similar across all species. This means that the ability of our auditory and motor systems to interact and move to music may be more widespread among species than previously thought. This new discovery offers not only further insight into the animal mind, but also into the origins of our own music and dance. 

    Can you move to the beat, or do you have two left feet? Apparently, how well we can time our movement to music depends somewhat on our innate genetic ability, and this skill was previously thought to be a uniquely human trait. While animals also react to hearing noise, or might make rhythmic sounds, or be trained to respond to music, this isn’t the same as the complex neural and motor processes that work together to enable us to naturally recognize the beat in a song, respond to it or even predict it. This is referred to as beat synchronicity.

    Only relatively recently, research studies (and home videos) have shown that some animals seem to share our urge to move to the groove. A new paper by a team at the University of Tokyo provides evidence that rats are one of them. “Rats displayed innate — that is, without any training or prior exposure to music — beat synchronization most distinctly within 120-140 bpm (beats per minute), to which humans also exhibit the clearest beat synchronization,” explained Associate Professor Hirokazu Takahashi from the Graduate School of Information Science and Technology. “The auditory cortex, the region of our brain that processes sound, was also tuned to 120-140 bpm, which we were able to explain using our mathematical model of brain adaptation.”

    But why play music to rats in the first place? “Music exerts a strong appeal to the brain and has profound effects on emotion and cognition. To utilize music effectively, we need to reveal the neural mechanism underlying this empirical fact,” said Takahashi. “I am also a specialist of electrophysiology, which is concerned with electrical activity in the brain, and have been studying the auditory cortex of rats for many years.”

    The team had two alternate hypotheses: The first was that the optimal music tempo for beat synchronicity would be determined by the time constant of the body. This is different between species and much faster for small animals compared to humans (think of how quickly a rat can scuttle). The second was that the optimal tempo would instead be determined by the time constant of the brain, which is surprisingly similar across species. “After conducting our research with 20 human participants and 10 rats, our results suggest that the optimal tempo for beat synchronization depends on the time constant in the brain,” said Takahashi. “This demonstrates that the animal brain can be useful in elucidating the perceptual mechanisms of music.”

    The rats were fitted with wireless, miniature accelerometers, which could measure the slightest head movements. Human participants also wore accelerometers on headphones. They were then played one-minute excerpts from Mozart’s Sonata for Two Pianos in D Major, K. 448, at four different tempos: Seventy-five percent, 100%, 200% and 400% of the original speed. The original tempo is 132 bpm and results showed that the rats’ beat synchronicity was clearest within the 120-140 bpm range. The team also found that both rats and humans jerked their heads to the beat in a similar rhythm, and that the level of head jerking decreased the more that the music was sped up.

    “To the best of our knowledge, this is the first report on innate beat synchronization in animals that was not achieved through training or musical exposure,” said Takahashi. “We also hypothesized that short-term adaptation in the brain was involved in beat tuning in the auditory cortex. We were able to explain this by fitting our neural activity data to a mathematical model of the adaptation. Furthermore, our adaptation model showed that in response to random click sequences, the highest beat prediction performance occurred when the mean interstimulus interval (the time between the end of one stimulus and the start of another) was around 200 milliseconds (one-thousandth of a second). This matched the statistics of internote intervals in classical music, suggesting that the adaptation property in the brain underlies the perception and creation of music.”

    As well as being a fascinating insight into the animal mind and the development of our own beat synchronicity, the researchers also see it as an insight into the creation of music itself. “Next, I would like to reveal how other musical properties such as melody and harmony relate to the dynamics of the brain. I am also interested in how, why and what mechanisms of the brain create human cultural fields such as fine art, music, science, technology and religion,” said Takahashi. “I believe that this question is the key to understand how the brain works and develop the next-generation AI (artificial intelligence). Also, as an engineer, I am interested in the use of music for a happy life.”

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    Paper Title:

    Yoshiki Ito, Tomoyo Isoguchi Shiramatsu, Naoki Ishida, Karin Oshima, Kaho Magami, Hirokazu Takahashi. Spontaneous beat synchronization in rats: Neural dynamics and motor entrainment. Science Advances 8, eabo7019 (2022). DOI: 10.1126/sciadv.abo7019

    Funding: 

    This work was supported in part by JSPS KAKENHI (20H04252, 21H05807) and JST Moonshot R & D program (JPMJMS2296).

    Useful Links:

    Graduate School of Information Science and Technology: https://www.i.u-tokyo.ac.jp/index_e.shtml

    Hirokazu Takahashi Lab: http://www.ne.t.u-tokyo.ac.jp/index-e.html  

    About the University of Tokyo
    The University of Tokyo is Japan’s leading university and one of the world’s top research universities. The vast research output of some 6,000 researchers is published in the world’s top journals across the arts and sciences. Our vibrant student body of around 15,000 undergraduate and 15,000 graduate students includes over 4,000 international students. Find out more at www.u-tokyo.ac.jp/en/ or follow us on Twitter at @UTokyo_News_en.

    University of Tokyo

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  • Opening the eye of the storm

    Opening the eye of the storm

    Newswise — For the first time, high-energy muon particles created in the atmosphere have allowed researchers to explore the structures of storms in a way that traditional visualization techniques, such as satellite imaging, cannot. The detail offered by this new technique could aid researchers modeling storms and related weather effects. This could also lead to more accurate early warning systems.

    It’s hard not to notice the number of stories in the news about heavy storms in different parts of the world, often attributed to climate change. Weather prediction and early warning systems have always been important, but with increased storm activity it seems especially so these days. A team of researchers, led by Professor Hiroyuki Tanaka from Muographix at the University of Tokyo, offer the world of meteorology a novel way of detecting and exploring tropical cyclones using a quirk of particle physics that takes place above our heads all the time.

    “You’ve probably seen photographs of cyclones taken from above, showing swirling vortices of clouds. But I doubt you’ve ever seen a cyclone from the side, perhaps as a computer graphic, but never as actual captured sensor data,” said Tanaka. “What we offer the world is the ability to do just this, visualize large-scale weather phenomena like cyclones from a 3D perspective, and in real time too. We do this using a technique called muography, which you can think of like an X-ray, but for seeing inside truly enormous things.”

    Muography creates X-ray-like images of large objects, including volcanoes, the pyramids, bodies of water, and now, for the first time, atmospheric weather systems. Special sensors called scintillators are joined together to make a grid, a little like the pixels on your smartphone’s camera sensor. However, these scintillators don’t see optical light, but instead see particles called muons which are created in the atmosphere when cosmic rays from deep space collide with the atoms in the air. Muons are special because they pass through matter easily without scattering as much as other types of particles. But the small amount they do deviate by as they pass through solid, liquid, or even gaseous matter, can reveal details of their journey between the atmosphere and the sensors. By capturing a large number of muons passing through something, an image of it can be reconstructed.

    “We successfully imaged the vertical profile of a cyclone, and this revealed density variations essential to understanding how cyclones work,” said Tanaka. “The images show cross sections of the cyclone which passed through Kagoshima Prefecture in western Japan. I was surprised to see clearly it had a low-density warm core that contrasted dramatically with the high-pressure cold exterior. There is absolutely no way to capture such data with traditional pressure sensors and photography.”

    The detector the researchers used has a viewing angle of 90 degrees, but Tanaka envisages combining similar sensors to create hemispherical and therefore omnidirectional observation stations which could be placed along the length of a coastline. These could potentially see cyclones as far away as 300 kilometers. Although satellites already track these storms, the extra detail offered by muography could improve predictions about approaching storms.

    “One of the next steps for us now will be to refine this technique in order to detect and visualize storms at different scales,” said Tanaka. “This could mean better modeling and prediction not only for larger storm systems, but more local weather conditions as well.”

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    Journal article: Hiroyuki K.M. Tanaka, Jon Gluyas, Marko Holma, Jari Joutsenvaara, Pasi Kuusiniemi, Giovanni Leone, Domenico Lo Presti, Jun Matsushima, László Oláh, Sara Steigerwald, Lee F. Thompson, Ilya Usoskin, Stepan Poluianov, Dezső Varga, Yusuke Yokota. “Atmospheric Muography for Imaging and Monitoring Tropic Cyclones”. Scientific Reports.

     

    About The University of Tokyo
    The University of Tokyo is Japan’s leading university and one of the world’s top research universities. The vast research output of some 6,000 researchers is published in the world’s top journals across the arts and sciences. Our vibrant student body of around 15,000 undergraduate and 15,000 graduate students includes over 4,000 international students. Find out more at www.u-tokyo.ac.jp/en/ or follow us on Twitter at @UTokyo_News_en.

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