Mysterious outbreak of bone-eating TB resembled an ancestral form

Driving force behind strange NC outbreak solved by a Duke collaboration

Peer-Reviewed Publication

DUKE UNIVERSITY

DURHAM, N.C. –  Tuberculosis is usually encountered as a disease of the lungs, but in 2 percent of cases in the U.S. it can also be found in the bones. The 9,000-year-old skeletons of some Egyptian mummies show signs of having tuberculosis infection in their bones, a painful condition that leaves the bones looking like they’ve been gnawed. 

So it was a weird puzzle when Duke physician Jason Stout M.D. encountered a Wake County TB outbreak in the mid-2000s in which the infection had spread beyond the lungs in six people. “Four out of six were in the bone,” Stout said. “That’s way more than 2 percent.”

The index case, the first person in Raleigh to have this strain of the disease, apparently contracted the bacterium in Vietnam, but he wasn’t feeling very sick and had been working around 400 people in his workplace.

“So it was prolonged exposure in a workplace,” said Stout, a Duke professor of medicine who tracked down and identified seven subsequent infections through contact tracing and health department records.

All eight people were treated with antibiotics and other co-workers received preventative care and then the strange outbreak went away. But the mystery was never really solved. “I’m an epidemiologist and clinical trial specialist and I was left scratching my head,” Stout said.

Until several years later when Stout had a chance conversation with his colleague and TB researcher David Tobin, Ph.D., an associate professor in molecular genetics and microbiology and immunology at Duke.

“We met up and we're having coffee one day, and we're talking about this,” Stout recalls. Academic medical centers like Duke routinely keep biological specimens, and Stout still had samples of the puzzling bug. “David said, ‘Well, give it to me and we'll take a look.’ And then this amazing science came from that,” Stout said.

The amazing science is that Tobin’s lab, with several colleagues at Duke, Notre Dame, and the University of Texas, figured out precisely how and why these particular TB bacteria were so mobile. Their findings appear online Nov. 9 in the journal Cell.

“Certain infections tend to go certain places,” Stout said. “And the question is always, why does it do that?” In TB strains found in the Americas and Europe, the bacteria seem more likely to stay put in the lungs. But this strain was highly mobile.

Tobin’s team, led by Joseph Saelens, Mollie Sweeney and Gopinath Viswanathan, ran genetic sequencing on the Raleigh bug and found it most resembled an ancestral strain from a group of strains called lineage 1. In the U.S. we tend to see the modern strains, lineages 2, 3, and 4, but lineage 1 is still out there, mostly in South and Southeast Asia.

Mycobacterium tuberculosis generally infects a type of white blood cell called a macrophage, a highly mobile street sweeper cell that moves around looking for invaders and then engulfs them and chews them up. (Macrophage is Latin for big eater.) One part of the pathogenic bacteria’s toolkit is a set of unique chemical signals – secreted factors -- to protect itself from the immune system and tell its macrophage host what to do.

Tobin’s team wanted to find the difference that allowed the Wake County bug’s macrophages to be more mobile and leave the lungs.

They compared genetic variants from 225 different strains of TB with particular attention to the genes for their secreted factors. What they found is a secretion factor called EsxM that was active in the Raleigh bacteria, but had been inactivated by a mutation in the modern strains.

Then, working with Craig Lowe, an evolutionary biologist and assistant professor of molecular genetics and microbiology at Duke, they looked at genetic sequencing from 3236 different strains of TB and found the pattern persisted: the modern strains have a silenced version of the EsxM secretion factor. “Over a few thousand strains, that really holds up,” Tobin said. “They’ve maintained that and presumably it’s something that’s evolutionarily advantageous to them.”

To further prove their point, the researchers put active versions of EsxM into safely attenuated versions of modern strains and watched as their macrophage hosts in a lab dish became more active and mobile. “We can see these changes in macrophage shape and structure and they become more migratory,” Tobin said. They also knocked out EsxM in a strain with the ancestral version and made the infected macrophages less mobile.

While being careful not to overstate their findings, Tobin said it would appear that the broadly distributed modern strains of TB benefit from staying within the lungs because of the way they spread through the air by breathing. Staying in the lungs would presumably give them a better launching pad to a new host.

Fortunately, the migratory TB strain hasn’t been seen again locally, Stout said, “hopefully because we did good work and got a lot of people preventative therapy.” But the mystery of its strange mobility has been solved.

“This may well have ended with me saying, ‘Wow, that was weird. There’s got to be something about the strain because all these patients had healthy immune systems,’” Stout said. “But the kind of science that I do is not the kind of science that David does. This is a wonderful example of people from different disciplines coming together to answer a really interesting clinical problem.”

This research was supported by the National Institutes of Health (AI-125517, AI-130236, AI-127115, AI-142127, AI-149147, AI-106872, 1DP2-GM146458-01, UC6-AI-058607).

CITATION: “An Ancestral Mycobacterial Effector Promotes Dissemination of Infection,” Joseph W. Saelens, Mollie I. Sweeney, Gopinath Viswanathan, Ana María Xet-Mull, Kristen L. Juric Smith, Dana M. Sisk, Daniel D. Hu, Rachel M. Cronin, Erika J. Hughes, W. Jared Brewer, Jörn Coers, Matthew M. Champion, Patricia A. Champion, Craig B. Lowe, Claire M. Smith, Sunhee Lee, Jason E. Stout, David M. Tobin. Cell, Nov. 9, 2022. DOI: 10.1016/j.cell.2022.10.019

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JOURNAL

Cell

DOI

10.1016/j.cell.2022.10.019 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Cells

ARTICLE TITLE

An Ancestral Mycobacterial Effector Promotes Dissemination of Infection

ARTICLE PUBLICATION DATE

9-Nov-2022

BEHIND CUBA

Decades-long push to lower stillbirth rate in the US has stalled, Rutgers-led research finds

A study published in The Lancet shows no progress since mid-2000s in reducing stillbirth risk.

Peer-Reviewed Publication

RUTGERS UNIVERSITY

A decades-long effort to lower the stillbirth rate in the United States has stalled, as has progress in closing a persistent gap in excess stillbirths experienced by Black women compared with White women, according to a Rutgers-led study.

“Over the last 40 years, we have reduced certain risk factors for stillbirth, such as smoking and alcohol use before and during pregnancy, but these gains have been countered by substantial increases in other risk factors, like obesity and structural racism,” said Cande Ananth, chief of Epidemiology and Biostatistics in the Department of Obstetrics, Gynecology and Reproductive Sciences at the Rutgers Robert Wood Johnson Medical School and lead author of the study published in The Lancet Regional Health – Americas.

“Our findings illustrate that past progress has now been offset by these newly identified risks,” Ananth said.

To determine how cultural and environmental factors impact stillbirths among Black and White women in the U.S., Ananth and a team of Rutgers obstetricians examined changes in stillbirth rates between 1980 and 2020.

Using data compiled by the National Center for Health Statistics of the Centers for Disease Control and Prevention and covering all 50 states and the District of Columbia, the researchers measured how maternal age, year of death (indicative of changes in prenatal and intrapartum care and other factors) and maternal birth cohorts (indicative of social and environmental elements,  such as socioeconomic status, education, nutrition and substance use at the time of the women’s birth) shaped stillbirth trends.

More than 157 million live births and nearly 711,000 stillbirths delivered at 24 or more weeks over the last four decades in the U.S. were included in the study.

Consistent with previous studies, the researchers found that total stillbirth rates in the U.S. declined steadily between 1980 and 2005, backed by advances in prenatal care and maternal health. For every 1,000 women who delivered in 1980, 10 of those pregnancies ended in stillbirth. By 2005, the figure had declined to about 5 per 1,000.

But since then, the researchers found, improvements have flatlined and the rate today is about the same as it was more than a decade ago.

Additionally, despite efforts to reduce structural racism and increase health-care access to women of color, the disparity in stillbirth rates for Black women compared with White women remained unchanged during the 40-year period. The rate for Black women was about twice the rate of White women in 1980 (17.4 versus 9.2 per 1,000 births) and remained twofold in 2020 (10.1 versus 5.0 per 1,000 births).

Unlike most previous work, which has focused primarily on risks such as age at delivery and social and environmental conditions, Ananth’s study added a third element: the birth cohort – the year the mother herself was born.

Ananth said that the data demonstrates a strong link between birth cohort and stillbirth risk.

“The cohort is a new dimension to understanding these adverse outcomes,” said Ananth. “To understand the paper’s significance, you need to view it in a three-dimensional perspective. We have age of the mother, year of delivery and the birth cohort. All three factors are time-related and intertwined.”

Several factors might explain the stalled decline in reducing stillbirth rates. One possible cause, the researchers wrote, is a national effort in 2009 to reduce elective deliveries before 39 weeks. There also may have been a slowdown in medical advances and obstetrical intervention to predict or prevent stillbirth.

The persistent gap in stillbirth disparities is more complicated and includes structural racism and biases, social inequality and a greater burden of chronic diseases and illness, Ananth said.

Taken together, Ananth said these data paint a dire health care picture that needs urgent attention at local, state and national levels.

“I am a firm believer that even one death is one too many,” he said. “Delivering a stillbirth carries so much social and emotional trauma – for the parents, and for the entire society.”

JOURNAL

The Lancet

DOI

10.1016/j.lana.2022.100380 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Evolving stillbirth rates among Black and White women in the United States, 1980–2020: A population-based study

How we experience the pain of other people?

Peer-Reviewed Publication

NETHERLANDS INSTITUTE FOR NEUROSCIENCE - KNAW

A new study from the Netherlands Institute for Neuroscience recorded from neurons of human patients to show that the pain of others is directly mapped onto neurons in the insula – a brain region critical for our own emotions.

Sharing the distress of others is considered key to empathy and our motivation to help others. With people greatly differing in their ability to empathize, and some psychiatric patients lacking the ability to empathize, understanding how our brain makes the pain of others feel painful is key to understanding the origin of these individual differences.

So far, we have had to rely on fMRI studies to identify brain regions that become activated while we perceive the pain of others. Unfortunately, fMRI cannot directly measure the activity of neurons. Instead it measures changes in blood-flow that help pinpoint brain regions that are associated with empathy. To understand where in the brain neurons help us share the distress of others, we would need to insert electrodes into the brain, and directly measure the electrical activity through which neurons process information. For obvious reasons, this is not possible in humans, or is it?

Epilepsy patients

In certain cases of epilepsy that cannot be treated using pharmacological treatments, surgeons implant electrodes directly into the brain of patients, to localize the origin of the epilepsy. The patients then have to stay in the hospital for about a week, while the surgical team records their brain activity and waits for an epileptic event to occur. To add purpose to this waiting, some patients volunteer a unique opportunity to better understand the human mind: they engage in psychological tasks while their brain activity is measured through these medical electrodes.

In a new paper published in the prestigious journal eLife, a collaboration between NIN researchers Efe Soyman, Rune Bruls, Kalliopi Ioumpa under the supervision of professors Christian Keysers and Valeria Gazzola leveraged this unique opportunity to test the notion that neurons in brain regions involved in our own pain, like the insula, contain neurons with activity that directly mirrors the pain of others. They showed patients short video-clips of a woman experiencing various levels of pain, and measured how strongly neurons in the insula – a brain region involved in the patient's own pain experiences – respond to the pain they observe the woman in the video-clip to experience. Specifically, they could measure intracranial local field potentials, which measure the activity of some hundreds of insula neurons close to the electrode, from 7epilepsy patients. In addition, they could zoom into the activity of individual neurons in the insula of 3 epilepsy patients.

Background: The insula and our own emotions

The insula, a brain region hidden inside of the brain, is known to play a critical role in our own emotions. It can sense the state of our body through input from our inner organs and skin, and integrates this information with what we see, hear and smell, and is thought to give rise to these conscious feelings we call emotions. In particular, it has also been shown to contain many neurons that respond when we experience pain in or on our own body, with the level of its activity scaling with how unpleasant we find this pain.

The novelty: coding the pain of others

The team therefore explored whether neurons in this region would also represent the level of pain experiences by others. Because the movies they showed participants varied in how much pain the actress in the movies was experiencing, the team could explore whether movies in which the patients perceived others to be in more pain would be movies in which the insular neurons would show more activity – serving as a mirror for other people’s pain. This is exactly what they found: throughout the insula, they could record electrical activity that scaled with the pain the people reported perceiving in the movies. This was true in the local field potentials, and even in individual neurons, providing the first evidence, that a brain region involved in our own pain, contains a fine-grained representation of how much pain others experience.

Using advanced data analysis methods, the team could take the level of electrical activity in the insula during each movie, and predict how the patient would respond to the question: “how intense do you think the pain was that the person in the movie experienced”. By offering the unique opportunity to directly record from their brain, the patients thus provided us with a key insight into human empathy: it really looks as though we empathize with the pain of others because our brains are wired to transform their pain into activity in regions involved in our own pain.

How do we perceive the pain of others?

The team provided further insights into how we perceive the pain of others. In half the videos, the camera was focused on the facial expression of the actress, which was seen to unfold from a neutral expression to one of varying degree of pain in a period of about one second. Analyzing the electrical responses in the insula and the muscle movements of the actress in the movies revealed that what the brain appears to use to perceive the pain of others was not the movement per se, but simply how contracted the eyes of the actress ended up being. In the other half, the camera was focusing on the hand of the actress, and showed a belt hitting the hand. In that case, the brain appeared to deduce the amount of pain from processing how much the hand was moving under the action of the belt. Together, this revealed intricate details of how flexibly the human brain transforms what we see others do into a fine-grained perception of their inner states.

While this study focused on a single brain region, the insula, that fMRI studies had suggested to be important for empathy, future research of the team will aim to combine the data from all recorded electrodes. They can then develop a map of where in the brain, the pain of others is transformed into the nuanced empathy we can have for other people’s emotions, and pinpoint the locations in which differences across individuals could account for the striking differences in empathy we can observe around us.

Acknowledgements:

This work was made possible through a tight collaboration between the members of the social brain lab that designed the tasks and analysed the data (Efe Soyman, Rune Bruls, Kalliopi Ioumpa, Laura Müller-Pinzler, Selene Gallo, Chaoyi Qin, Christian Keysers and Valeria Gazzola), clinicians at the VUmc in Amsterdam that performed the surgeries and helped in data acquisition (Elisabeth CW van Straaten, Johannes C Baayen, Sander Idema), and the team of Prof. Pieter Roelfsema and Matt Self (Matthew W Self, Judith C Peters, Jessy K Possel) that have established the link between the fundamental research at the NIN and the clinicians at the VUmc, and also helped acquire the data. We extend our warmhearted gratitude to the patients that participate and thereby made these scientific insights possible.

Source: eLife: https://doi.org/10.7554/eLife.75197

Quotes:

Christian Keysers: “As a neuroscientist, our dream is to understand how neurons make us who we are. What these patients do, by allowing us to record from these electrodes, is to make that dream come true: we could see in real time, how the pain of someone else is mirrored in the neurons of an observer. After decades of working on empathy, we could see empathy unfold in the human insula”.

Efe Soyman: “Other people’s suffering can be inferred from a variety of indicators: a painful expression, the intensity of the event that inflicts pain in them, etc. With this incredibly valuable data we collected from the patients, we see how the human insula might tune into whichever is available among these various cues when we experience the pain of other people.”

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JOURNAL

eLife

DOI

10.7554/eLife.75197 

ARTICLE TITLE

Intracranial human recordings reveal association between neural activity and perceived intensity for the pain of others in the insula

Seals’ sense of rhythm may give us answers about our own musicality

New research from Aarhus University suggests that seals can both distinguish and react differently to different rhythms. A big step forward in understanding human musicality, says Associate Professor Andrea Ravignani

Peer-Reviewed Publication

AARHUS UNIVERSITY

New research from Aarhus University suggests that seals can both distinguish and react differently to different rhythms. A big step forward in understanding human musicality, says Associate Professor Andrea Ravignani.

When a small child develops language, the language centre is not the only part of the brain that is activated; a sense of rhythm goes hand in hand with language development for us humans. The same also applies to birds. Monkeys, on the other hand, turn out to have almost no sense of rhythm. But in fact, researchers currently know very little about whether other vocally-plastic mammals, like us, also pick up on and react to rhythms.

However, a new study from the Centre for Music in the Brain at the Department of Clinical Medicine at Aarhus University and Max Planck Institute for Psycholinguistics now suggests that seal pups do not just listen to, but also react differently to sounds played in different rhythms.

Associate Professor Andrea Ravignani is behind the study, in which the researchers tested a total of 20 harbour seal pups to see if they had an understanding of rhythm. Over a period of 30 minutes, the researchers played sequences of seal calls in different rhythmic variations and tempi. Some were quick, others slow, some were rhythmic, while others were irregular. The experiment showed that the seals reacted differently, depending on which rhythm the researchers played, says Andrea Ravignani.

“We filmed the seals’ reactions to the sounds and measured how many times they turned their heads to look at where the sounds were coming from. We then examined whether there was a difference between how many times the seals turned their heads, and how long they looked towards the sound, depending on the rhythm we played. This allowed us to see whether the different rhythms produced different reactions,” says Andrea Ravignani.

The method is also known from studies of babies’ reactions to sounds and rhythms, and although it may seem strange to investigate the rhythmic sense of seals, the study, according to Andrea Ravignani, may provide not only a better understanding of the seals’ sense of rhythm, but also of human language development.

“Our study represents a significant step forward in relation to our understanding of humankind’s own musicality and language development, about which we still don’t know very much today. By showing that another vocally plastic mammal can also perceive different rhythms, we support the scientific hypothesis that the two abilities are interconnected,” he says.

“We can conclude that even very young, untrained seals can distinguish vocalisations from other seals, based on their rhythms. It shows that we are not the only mammals to show rhythmic understanding and learn vocalisations. The two abilities may possibly have developed in parallel in both seals and human beings.”

More studies on the way

According to Andrea Ravignani, the study may be the first of its kind to link a spontaneous rhythmic understanding and the development of vocalisation in a mammal other than human beings. At the same time, it is worth noting, says Andrea Ravignani, that early in life the seal pups have a robust understanding of rhythm that has not been trained. The same intuitive rhythmic understanding is seen in human infants.

The study raises more questions, which the researchers hope to be able to answer in other studies, says Andrea Ravignani.

“Can seals detect rhythms in sounds other than seal sounds, such as sounds from other animals, or abstract sounds? Can they perceive more complex rhythms? Are seals unique in this, or do other mammals also have a sense of rhythm? And what are the biological and physiological mechanisms that support this ability? These are all questions to which we now hope to find the answers.”

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Behind the research results

• Type of study: Observational study
• Partners: Comparative Bioacoustics Group, Max Planck Institute for Psycholinguistics
• External funding: Max Planck Research Group (MPRG) 
• Link to the scientific article: https://doi.org/10.1098/rsbl.2022.0316

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JOURNAL

Biology Letters

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Spontaneous rhythm discrimination in a mammalian vocal learner

Your favorite songs reveal your attachment style: New psychology research

Peer-Reviewed Publication

UNIVERSITY OF TORONTO

What does having a particular artist on repeat tell us about how to — or how not to — navigate our romantic lives, friendships and family ties? Whether it’s Adele or The Weeknd on your go-to playlist, the lyrics can say a lot about you, and it’s all related to attachment styles, or how people typically think, feel and act in relationships.

“I’m interested in the role music plays in people’s lives. Since humans started making music tens of thousands of years ago, songs across cultures have always focused on relationships — getting into one, maintaining one or breaking up — so I wondered, do people listen to music that mirrors their experiences in relationships?” says Ravin Alaei, who graduated with a PhD from the Department of Psychology in the Faculty of Arts & Science in 2019.

In a new study published in the journal Personal Relationships, Alaei and Department of Psychology professors, Geoff Macdonald and Nicholas Rule, found that people’s individual attachment styles correspond with the lyrics of their favourite songs. In other words, we tend to return to the tunes that spell out what we’re going through in a relationship, for better or for worse.

“Lyrics matter, so pay attention to them,” says Alaei, who is also a physician who earned his MD at McMaster University. “The lyrics of your favourite songs about relationships may help validate your thoughts and feelings but may also reveal things about your experiences of relationships that you might not have realized — something that you’re going through repeatedly, that you keep coming up against.”

First, a refresher on attachment styles, which can roughly be considered as four categories, says Alaei. Anxiously attached people worry about being rejected and seek a lot of reassurance about their relationships. On the other hand, avoidantly attached people respond to their negative expectations of relationships by closing off emotions and intimacy in favour of independence. People with a mixed attachment style have confused expectations, fluctuating between clingy and cold. Lastly, secure people have optimistic outlooks on relationships, and are open communicators and trust their partners.

“We asked about 570 people to tell us their favourite songs, and then coded the nearly 7,000 songs for the attachment style that their lyrics expressed. In turn, we consistently found that avoidantly attached people prefer music with avoidant lyrics,” says Alaei. “I expected to see a clear relationship between anxiously attached people and anxious songs because they are the most emotional, but surprisingly, this was the most tenuous result.”

This strong avoidant connection is reflected not only on an individual level, but on a societal one as well. In a second study, the researchers coded over 800 Billboard number-one hits from 1946 to 2015 for their attachment themes and found that lyrics have become more avoidant and less secure over time.

“Popular music lyrics are running parallel to sociological trends of social disconnection — people valuing independence over reliance on others, and feeling more isolated,” says Alaei.

If we’re listening to music that reflects our relationships back at us, is that helping or hindering our relationship skills? Alaei says this is the next step in the research.

Take Adele’s discography for example, which Alaei says tips the scale towards anxiously attached themes and was popular among participants. “Someone Like You” appeared on many playlists, with the refrain: “I hate to turn up out of the blue uninvited / But I couldn’t stay away, I couldn’t fight it / I had hoped you’d see my face and that you’d be reminded / That for me it isn’t over.”

If someone is an anxiously attached person, will listening to “Someone Like You” on repeat cause more harm than good? According to Alaei, it all starts with self-awareness of your own attachment style.

“As an anxious person, you should recognize that you’re vulnerable to a negative feedback loop, and your emotions snowballing,” says Alaei. “Music can be a very powerful exacerbator of that because it can stimulate deep emotions and memories, ultimately reinforcing your worries.”

Adele fans may be having very different relationship experiences compared to those listening to The Weeknd’s “Heartless.” With lyrics like “Tryna be a better man but I'm heartless / Never be a wedding plan for the heartless / Low life for life 'cause I'm heartless,” it’s a prime example of an avoidant song, says Alaei.

His advice: “Listen to the song a few times to help you process what you’re going through and express your thoughts and feelings. You can decide whether listening to songs that reflect your experiences back at you is either helping you or reinforcing destructive behaviours for yourself. At some point, you may find it more productive to listen to music that provides a sense of security.”

A popular throwback among participants was Sonny & Cher’s “I Got You Babe”: “Then put your little hand in mine / There ain’t no hill or mountain we can’t climb.”

“It’s pretty much a manual on how to be securely attached,” says Alaei.

What do your favourite songs about relationships reveal about your attachment style? Here are some of the tunes that research participants chose for their playlists:

Avoidant songs:

• Beyoncé, Irreplaceable
• Chris Brown, Say Goodbye 
• N'Sync, Bye Bye Bye
• Michael Jackson, Billie Jean
• TLC, Scrubs
• Rihanna, Take a Bow
• The Weeknd, The Hills; Heartless

Anxious songs:

• Adele, Someone Like You
• The Police, Every Breath You Take
• Miley Cyrus, Wrecking Ball
• Adele, Hello
• U2, One
• Seether, Broken
• No Doubt, Don't Speak
• Bruno Mars, When I Was Your Man
• Drake, Hotline Bling

Secure songs:

• Sonny & Cher, I Got You Babe
• Whitney Houston, I Will Always Love You
• The Beatles, Love Me Do
• Ed Sheeran, Thinking Out Loud
• Plain White Ts, I Love You 
• John Legend, All of Me
• Michael Bublé, Haven't Met You Yet
• Beach Boys, Wouldn't It Be Nice
• Bryan Adams, (Everything I Do) I Do It for You
• Etta James, At Last
• Justin Bieber, Holy

Anxious-Avoidant (mixed) songs:

• Carrie Underwood, Before He Cheats
• Gotye, Somebody that I Used to Know
• Taylor Swift, Bad Blood
• Sam Smith, I'm Not the Only One
• Ne Yo, So Sick
• Bonnie Raitt, I Can't Make You Love Me
• Adele, Rolling in the Deep
• Rihanna ft. Drake, Work
• Eminem ft. Rihanna, Love the Way You Lie

 

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JOURNAL

Personal Relationships

DOI

10.1111/pere.12448 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Individuals' favorite songs' lyrics reflect their attachment style

Rats bop to the beat

Rats can move their heads in time to music, demonstrating innate beat synchronization in animals for the first time

Peer-Reviewed Publication

UNIVERSITY OF TOKYO

 

VIDEO: ALTHOUGH THE MAIN STUDY FOCUSED ON RESPONSES TO K. 448 BY MOZART, FOUR OTHER MUSICAL PIECES WERE ALSO PLAYED TO THE HUMAN AND ANIMAL PARTICIPANTS: BORN THIS WAY BY LADY GAGA, ANOTHER ONE BITES THE DUST BY QUEEN, BEAT IT BY MICHAEL JACKSON AND SUGAR BY MAROON 5. view more 

CREDIT: 2022 ITO ET AL.

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.”

####

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  

Research contact:
Associate Professor Hirokazu Takahashi
Department of Mechano-Informatics,

Graduate School of Information Science and Technology,

The University of Tokyo,
7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan

Email: takahashi@i.u-tokyo.ac.jp

Press contact:
Mrs. Nicola Burghall
Public Relations Group, The University of Tokyo,
7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
press-releases.adm@gs.mail.u-tokyo.ac.jp

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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JOURNAL

Science Advances

DOI

10.1126/sciadv.abo7019 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Spontaneous beat synchronization in rats: Neural dynamics and motor entrainment

ARTICLE PUBLICATION DATE

11-Nov-2022

Caltech Hall is getting stiffer, according to decades of data

Peer-Reviewed Publication

SEISMOLOGICAL SOCIETY OF AMERICA

 

IMAGE: CALTECH HALL view more 

CREDIT: ETHAN WILLIAMS

Caltech Hall, a 55-year-old nine-story reinforced concrete building on the Caltech campus, has been getting structurally stiffer over the past 20 years, according to a new report published in The Seismic Record.

Previous work by seismologists and engineers had documented the building softening—that is, decreasing in stiffness—from its construction in 1967 through 2002. This trend has reversed, and today the building is back to the state it was in 1986.

This unexpected conclusion was discovered by analyzing seismic data recorded continuously since 2001 on the building’s ninth floor.

Seismic data can be used to calculate the natural frequencies of a building, a measure of its vibration in response to forcing from earthquakes and strong winds. The natural frequencies are a proxy for structural stiffness; generally, the lower the frequency, the more “flexible” the building is during an earthquake.

Caltech Ph.D. student Ethan Williams and colleagues show that for Caltech Hall (formerly known as Millikan Library), the natural frequencies have increased gradually by about 5% in the east-west direction and 2% in the north-south direction over the past 20 years. These frequencies have varied by as much as 9.7% over scales from seconds to decades, they found, implying up to 20% variation in the building’s stiffness between earthquakes.

“Engineers generally assume that buildings are either stable or degrade over their lifetime,” said Williams. “There’s no expectation, or really any understood mechanism, for how a concrete building should be getting stiffer.”

In addition to the 20-year increasing trend, researchers found that the building’s natural frequencies varied depending on season and rainfall, as well as non-structural renovations such as removing library shelving on some floors and replacing it with plastic cubicles.

Such large variability poses a significant challenge for seismic structural health monitoring, according to Williams. “Most instrumented buildings have triggered seismometers, meaning that we only get to measure a building’s natural frequencies when there’s an earthquake,” he said. “If the stiffness can vary by 20% between earthquakes, then detecting earthquake damage just by looking for changes in stiffness may be unreliable.”

The researchers also found substantial short-term changes in the natural frequencies, after analyzing data collected during earthquakes and forced vibrations. Williams and colleagues documented rapid decreases in frequencies (building softening) at the onset of shaking like that from an earthquake, followed by a slower recovery over minutes. The stronger the shaking, the softer the building appeared.

It's interesting that the building is getting stiffer, Williams said, “but the short-term dynamic elasticity is at least as important for engineering practice.” As an example, Williams points to probabilistic seismic hazard analysis: “Ground motions used in structural design are often expressed in terms of spectral acceleration, which bakes in the assumption of linear, time-invariant elasticity. If a building’s natural frequencies are continuously changing over the course of an earthquake, then spectral acceleration isn’t going to accurately represent the peak motions for a given event.”

As for the cause of Caltech Hall’s wandering natural frequencies, Williams and colleagues offer a few suggestions, but they stress that these are just speculation. For instance, groundwater that migrates through cracks in the foundation could deposit calcite that heals those cracks, increasing the building’s stiffness over years to decades. During strong shaking, pre-existing fractures in the concrete could open up or soil beneath the foundation could shift, causing the temporary softening.

Better explanations may come as continuous seismic data is recorded in more buildings, according to Williams. “There are so few buildings with continuous instrumentation that there’s a real question, is Caltech Hall just special and interesting, or are all reinforced concrete buildings so complicated and dynamic?” he said.

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JOURNAL

The Seismic Record

DOI

10.1785/0320220032 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Variability in the Natural Frequencies of a Nine‐Story Concrete Building from Seconds to Decades

ARTICLE PUBLICATION DATE

11-Nov-2022

Researchers cook up a new way to remove microplastics from water

Peer-Reviewed Publication

PRINCETON UNIVERSITY, ENGINEERING SCHOOL

 

IMAGE: THE STRUCTURE OF THE AEROGEL IS FORMED BY GRAPHENE SHEETS STRETCHED ACROSS CARBON FIBER NETWORKS. view more 

CREDIT: SHAHARYAR WANI

Researchers at Princeton Engineering have found a way to turn your breakfast food into a new material that can cheaply remove salt and microplastics from seawater.

The researchers used egg whites to create an aerogel, a lightweight and porous material that can be used in many types of applications, including water filtration, energy storage, and sound and thermal insulation. Craig Arnold, the Susan Dod Brown Professor of Mechanical and Aerospace Engineering and vice dean of innovation at Princeton, works with his lab to create new materials, including aerogels, for engineering applications.

One day, sitting in a faculty meeting, he had an idea.

“I was sitting there, staring at the bread in my sandwich,” said Arnold. “And I thought to myself, this is exactly the kind of structure that we need.” So he asked his lab group to make different bread recipes mixed with carbon to see if they could recreate the aerogel structure he was looking for. None of them worked quite right initially, so the team kept eliminating ingredients as they tested, until eventually only egg whites remained.

“We started with a more complex system,” Arnold said, “and we just kept reducing, reducing, reducing, until we got down to the core of what it was. It was the proteins in the egg whites that were leading to the structures that we needed.”

Egg whites are a complex system of almost pure protein that — when freeze-dried and heated to 900 degrees Celsius in an environment without oxygen — create a structure of interconnected strands of carbon fibers and sheets of graphene. In a paper published Aug. 24 in Materials Today, Arnold and his coauthors showed that the resulting material can remove salt and microplastics from seawater with 98% and 99% efficiency, respectively.

“The egg whites even worked if they were fried on the stove first, or whipped,” said Sehmus Ozden, first author on the paper. Ozden is a former postdoctoral research associate at the Princeton Center for Complex Materials and now a scientist at Aramco Research Center. While regular store-bought egg whites were used in initial tests, Ozden said, other similar commercially available proteins produced the same results.

“Eggs are cool because we can all connect to them and they are easy to get, but you want to be careful about competing against the food cycle,” said Arnold. Because other proteins also worked, the material can potentially be produced in large quantities relatively cheaply and without impacting the food supply. One next step for the researchers, Ozden noted, is refining the fabrication process so it can be used in water purification on a larger scale.

If this challenge can be solved, the material has significant benefits because it is inexpensive to produce, energy-efficient to use and highly effective. “Activated carbon is one of the cheapest materials used for water purification. We compared our results with activated carbon, and it’s much better,” said Ozden. Compared with reverse osmosis, which requires significant energy input and excess water for operation, this filtration process requires only gravity to operate and wastes no water.

While Arnold sees water purity as a “major grand challenge,” that is not the only potential application for this material. He is also exploring other uses related to energy storage and insulation.

The research included contributions from the departments of chemical and biological engineering and geosciences at Princeton and elsewhere. “It’s one thing to make something in the lab,” said Arnold, “and it’s another thing to understand why and how.” Collaborators who helped answer the why and how questions included professors Rodney Priestley and A. James Link from chemical and biological engineering, who helped identify the transformation mechanism of the egg white proteins at the molecular level. Princeton colleagues in geosciences assisted with measurements of water filtration.

Susanna Monti of the Institute for Chemistry of Organometallic Compounds and Valentina Tozzi from Instituto Nanoscienze and NEST-Scuola Normale Superiore created the theoretical simulations that revealed the transformation of egg white proteins into the aerogel.

The article, “Egg protein derived ultralightweight hybrid monolithic aerogel for water purification,” was published in the journal Materials Today. Besides Arnold, Monti, Ozden, Priestley, Link and Tozzi, authors include Nikita Dutta, a former graduate student in mechanical and aerospace engineering who is now at the National Renewable Energy Laboratory; Stefania Gill, John Higgins and Nick Caggiano of Princeton University; and Nicola Pugno of the University of Trento and Queen Mary University of London. Support was provided in part by the Princeton Center for Complex Materials and the U.S. National Science Foundation.

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JOURNAL

Materials Today

DOI

10.1016/j.mattod.2022.08.001 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Egg protein derived ultralightweight hybrid monolithic aerogel for water purification