Study shows promising treatment for tinnitus

Tinnitus, the ringing, buzzing or hissing sound of silence, varies from slightly annoying in some to utterly debilitating in others. Up to 15% of adults in the United States have tinnitus, where nearly 40% of sufferers have the condition chronically and actively seek relief.

A recent study from researchers at the University of Michigan's Kresge Hearing Research Institute suggests relief may be possible.

Susan Shore, Ph.D., Professor Emerita in Michigan Medicine's Department of Otolaryngology and U-M's Departments of Physiology and Biomedical Engineering, led research on how the brain processes bi-sensory information, and how these processes can be harnessed for personalized stimulation to treat tinnitus.

Her team's findings were published in JAMA Network Open.

The study, a double-blind, randomized clinical trial, recruited 99 individuals with somatic tinnitus, a form of the condition in which movements such as clenching the jaw, or applying pressure to the forehead, result in a noticeable change in pitch or loudness of experienced sounds. Nearly 70% of tinnitus sufferers have the somatic form.

According to Shore, candidates with bothersome, somatic tinnitus, as well as normal-to-moderate hearing loss, were eligible to participate.

"After enrollment, participants received a portable device developed and manufactured by in2being, LLC, for in-home use," she said. "The devices were programmed to present each participant's personal tinnitus spectrum, which was combined with electrical stimulation to form a bi-sensory stimulus, while maintaining participant and study team blinding."

Study participants were randomly assigned to one of two groups. The first group received bi-sensory, or active, treatment first, while the second received sound-alone, or control, treatment.

For the first six weeks, participants were instructed to use their devices for 30 minutes each day. The next six weeks gave participants a break from daily use, followed by six more weeks of the treatment not received in the beginning of the study.

Shore notes that every week, participants completed the Tinnitus Functional Index, or TFI, and Tinnitus Handicap Inventory, or THI, which are questionnaires that measure the impact tinnitus has on individuals' lives. Participants also had their tinnitus loudness assessed during this time.

The team found that when participants received the bi-sensory treatment, they consistently reported improved quality of life, lower handicap scores and significant reductions in tinnitus loudness. However, these effects were not seen when receiving sound-only stimulation.

Further, more than 60% of participants reported significantly reduced tinnitus symptoms after the six weeks of active treatment, but not control treatment. This is consistent with an earlier study by Shore's team, which showed that the longer participants received active treatment, the greater the reduction in their tinnitus symptoms.

"This study paves the way for the use of personalized, bi-sensory stimulation as an effective treatment for tinnitus, providing hope for millions of tinnitus sufferers," said Shore.

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World's oldest meal helps unravel mystery of our earliest animal ancestors

The contents of the last meal consumed by the earliest animals known to inhabit Earth more than 550 million years ago has unearthed new clues about the physiology of our earliest animal ancestors, according to scientists from The Australian National University (ANU).

Ediacara biota are the world's oldest large organisms and date back 575 million years. ANU researchers found the animals ate bacteria and algae that was sourced from the ocean floor. The findings, published in Current Biology, reveal more about these strange creatures, including how they were able to consume and digest food.

The scientists analysed ancient fossils containing preserved phytosterol molecules -- natural chemical products found in plants -- that remained from the animals' last meal. By examining the molecular remains of what the animals ate, the researchers were able to confirm the slug-like organism, known as Kimberella, had a mouth and a gut and digested food the same way modern animals do. The researchers say it was likely one of the most advanced creatures of the Ediacarans.

The ANU team found that another animal, which grew up to 1.4 metres in length and had a rib-like design imprinted on its body, was less complex and had no eyes, mouth or gut. Instead, the odd creature, called Dickinsonia, absorbed food through its body as it traversed the ocean floor.

"Our findings suggest that the animals of the Ediacara biota, which lived on Earth prior to the 'Cambrian Explosion' of modern animal life, were a mixed bag of outright weirdos, such as Dickinsonia, and more advanced animals like Kimberella that already had some physiological properties similar to humans and other present-day animals," lead author Dr Ilya Bobrovskiy, from GFZ-Potsdam in Germany, said.

Both Kimberella and Dickinsonia, which have a structure and symmetry unlike anything that exists today, are part of the Ediacara biota family that lived on Earth about 20 million years prior to the Cambrian Explosion -- a major event that forever changed the course of evolution of all life on Earth.

"Ediacara biota really are the oldest fossils large enough to be visible with your naked eyes, and they are the origin of us and all animals that exist today. These creatures are our deepest visible roots," Dr Bobrovskiy, who completed the work as part of his PhD at ANU, said.

Study co-author Professor Jochen Brocks, from the ANU Research School of Earth Sciences, said algae are rich in energy and nutrients and may have been instrumental for Kimberella's growth.

"The energy-rich food may explain why the organisms of the Ediacara biota were so large. Nearly all fossils that came before the Ediacara biota were single-celled and microscopic in size," Professor Brocks said.

Using advanced chemical analysis techniques, the ANU scientists were able to extract and analyse the sterol molecules contained in the fossil tissue. Cholesterol is the hallmark of animals and it's how, back in 2018, the ANU team was able to confirm that Ediacara biota are among our earliest known ancestors.

The molecules contained tell-tale signatures that helped the researchers decipher what the animals ate in the lead up to their death. Professor Brocks said the difficult part was differentiating between the signatures of the fat molecules of the creatures themselves, the algal and bacterial remains in their guts, and the decaying algal molecules from the ocean floor that were all entombed together in the fossils.

"Scientists already knew Kimberella left feeding marks by scraping off algae covering the sea floor, which suggested the animal had a gut. But it was only after analysing the molecules of Kimberella's gut that we were able to determine what exactly it was eating and how it digested food," Professor Brocks said.

"Kimberella knew exactly which sterols were good for it and had an advanced fine-tuned gut to filter out all the rest.

"This was a Eureka moment for us; by using preserved chemical in the fossils, we can now make gut contents of animals visible even if the gut has since long decayed. We then used this same technique on weirder fossils like Dickinsonia to figure out how it was feeding and discovered that Dickinsonia did not have a gut."

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Birds warned of food shortages by neighbor birds change physiology and behavior to prepare

Songbirds learning from nearby birds that food supplies might be growing short respond by changing their physiology as well as their behavior, research by the Oregon State University College of Science shows.

After receiving social information from food-restricted neighbors for three days, the red crossbills in the study raised their pace of consumption, increased their gut mass and maintained the size of the muscle responsible for flight when their own eating opportunities were subsequently limited to two short feeding periods per day.

Findings of the study by OSU's Jamie Cornelius, published in the journal Proceedings of the Royal Society B, suggest that birds can use social information about food shortages to effect an adaptive advantage for survival.

"This is an entirely new form of physiological plasticity in birds and builds on prior work showing that social cues during stress can actually change how the brain processes stressors," said Cornelius, assistant professor of integrative biology.

Cornelius, an ecophysiologist, looks at the mechanisms that wild animals, particularly songbirds, use as they cope with unpredictable and extreme events in their environment, including fluctuations in food availability. Her research combines natural history, endocrinology and biotelemetry to probe for a better understanding of what limits an animal's fitness under difficult conditions.

"Animals have all kinds of strategies for dealing with challenging environments, ranging from seasonal avoidance strategies like hibernation or migration to behaviors like caching or altered foraging activity," she said. "Physiological adjustments in metabolic rate, digestive capacity and energy reserves can sometimes accompany behavioral changes, but those things can take time to execute. That means unpredictable environmental conditions are particularly challenging for many animals."

Cornelius showed in earlier research that a red crossbill with a food-restricted neighbor will secrete higher than usual levels of the stress hormone corticosterone during its own food-stress periods and also undergo brain activity changes that prepare the bird to respond more strongly to the challenge.

The red crossbill, known scientifically as Loxia curvirostra, is a nomadic species that migrates based on food availability and incorporates other birds' calls or behavior into its decision-making on how to respond to food deprivation.

Found throughout Europe and North America, the crossbill is a member of the finch family. It is known, as its name suggests, for upper and lower beak tips that cross, a feature that helps it pull seeds from conifer cones and other fruits.

"Crossbills are an interesting study system because of their dependence on conifer seeds," Cornelius said. "Conifer seed crops are somewhat unpredictable both in where seed crops develop each year and in how long a seed crop might support birds. We use crossbills as a study system to try to understand what strategies birds might have available when food suddenly declines because crossbills may have to cope with this more often than other species."

In this research, which involved crossbills in captivity, some of the birds received three days of social information from food-deprived birds prior to their own food limitations; other birds received three days of social information from food-deprived birds at the same time as their own food deprivation.

Cornelius refers to the former collection of birds as the social predictive focal group and the latter as the social parallel focal group.

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Researchers identify neuronal mechanisms that control food cravings during pregnancy

Many people have felt the sudden and uncontrollable urge to eat a certain food. These urges -- known as cravings -- are very common, mostly during pregnancy. During this time, the mother's body undergoes a series of physiological and behavioural changes to create a favourable environment for the embryo's development. However, the frequent consumption of tasty and high calorie foods -- derived from the cravings -- contributes to weight gain and obesity in pregnancy, which can have negative effects on the baby's health.

"There are many myths and popular beliefs regarding these cravings, although the neuronal mechanisms that cause them are not widely known," notes March Claret, lecturer at the Faculty of Medicine and Health Sciences of the University of Barcelona and head of the IDIBAPS Neuronal Control of Metabolism Group. Claret leads, together with the researcher Roberta Haddad-Tóvolli, a study published in the journal Nature Metabolism that provides new evidence on the alterations of the neuronal activity that drive cravings in an animal model.

Dopamine and compulsive eating behaviour

According to the results, during pregnancy, the brain of female mice undergoes changes in the functional connections of the brain reward circuits, as well as the taste and sensorimotor centers. Moreover, just like pregnant women, female mice are more sensitive to sweet food, and they develop binge-eating behaviours towards high calorie foods. "The alteration of these structures made us explore the mesolimbic pathway, one of the signal transmission pathways of dopaminergic neurons. Dopamine is a key neurotransmitter in motivational behaviours," notes Claret, member of the Department of Medicine of the UB and the Diabetes and Associated Metabolic Diseases Networking Biomedical Research Centre (CIBERDEM).

The team observed the levels of dopamine -- and the activity of its receptor, D2R -- to increase in the nucleus accumbens, a brain region involved in the reward circuit. "This finding suggests that the pregnancy induces a full reorganization of the mesolimbic neural circuits through the D2R neurons," notes Haddad-Tóvolli. "These neuronal cells -- and their alteration -- would be responsible for the cravings, since food anxiety, typical during pregnancy, disappeared after blocking their activity."

The team led by Claret and Haddad-Tóvolli showed that persistent cravings have consequences for the offspring. They affect the metabolism and development of neural circuits that regulate food intake, which leads to weight gain, anxiety and eating disorders. "These results are shocking, since many of the studies are focused on the analysis of how the mother's permanent habits -- such as obesity, malnutrition, or chronic stress -- affect the health of the baby. However, this study indicates that short but recurrent behaviours, such as cravings, are enough to increase the psychological and metabolic vulnerability of the offspring," concludes Claret.

The conclusions of the study could contribute to the improvement of nutritional guidelines for pregnant women in order to ensure a proper prenatal nutrition and prevent the development of diseases. Among the participants in the study were Guadalupe Soria and Emma Muñoz-Moreno (IDIBAPS), Analía Bortolozzi (IIBB-CSIC-IDIBAPS) and Emmanuel Valjent (INSERM and University of Montpelier).

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Even dim light before bedtime may disrupt a preschooler’s sleep

Even slight exposure to light can prompt the critical sleep-promoting hormone melatonin to plummet in preschoolers in the hour before bedtime, potentially disrupting slumber long after the light goes out, according to new CU Boulder research.

The study, published this month, is the latest in a series, funded by the National Institutes of Health, examining how the central body clock of young children is unique. It suggests that preschoolers are highly susceptible to the physiological impacts of light at night, and some children may be even more sensitive than others.

"Our previous work showed that one, fairly high intensity of bright light before bedtime dampens melatonin levels by about 90% in young children," said first author Lauren Hartstein, a postdoctoral fellow in the Sleep and Development Lab at CU Boulder. "With this study, we were very surprised to find high melatonin suppression across all intensities of light, even dim ones."

Light: The body's strongest time cue

Light is the body's primary time cue, influencing circadian rhythms that regulate everything from when we feel tired or hungry to what our body temperature is throughout the day.

When light hits the retina, a signal transmits to a part of the brain called the suprachiasmatic nucleus, which coordinates rhythms throughout the body, including nightly production of melatonin. If this exposure happens in the evening as melatonin is naturally increasing, it can slow or halt it, delaying the body's ability to transition into biological nighttime.

Because children's eyes have larger pupils and more transparent lenses than adults, light streams into them more freely. (One recent study showed that the transmission of blue light through a 9-year-old's eye is 1.2-times higher than that of an adult).

"Kids are not just little adults," said senior author Monique LeBourgeois, an associate professor of Integrative Physiology and one of the few researchers in the world to study the circadian biology of young children. "This heightened sensitivity to light may make them even more susceptible to dysregulation of sleep and the circadian system."

Research in a "cave"

To quantify how susceptible they are, the researchers collaborated with Colorado School of Mines mathematician Cecilia Diniz Behn for a new study.

They enlisted 36 healthy children, ages 3 to 5 years, for a nine-day protocol in which they wore a wrist monitor that tracked their sleep and light exposure. For seven days, parents kept the children on a stable sleep schedule to normalize their body clocks and settle them into a pattern in which their melatonin levels rose at about the same time each evening.

On the eighth day, researchers transformed the children's home into what they playfully described as a "cave" -- with black plastic on the windows and lights dimmed -- and took saliva samples every half hour starting in the early afternoon until after bedtime. This enabled the scientists to get a baseline of when the children's biological night naturally began and what their melatonin levels were.

On the last day of the study, the young study subjects were asked to play games on a light table in the hour before bedtime, a posture similar to a person looking at a glowing phone or tablet. Light intensity varied between individual children, ranging from 5 lux to 5,000 lux. (One lux is defined as the light from a candle 1 meter, or about 3 feet, away).

When compared to the previous night with minimal light, melatonin was suppressed anywhere from 70% to 99% after light exposure. Surprisingly, the researchers found little-to-no relationship between how bright the light was and how much the key sleep hormone fell. In adults, this intensity-dependent response has been well documented.

Even in response to light measured at 5 to 40 lux, which is much dimmer than typical room light, melatonin fell an average of 78%. And even 50 minutes after the light extinguished, melatonin did not rebound in more than half of children tested.

"Together, our findings indicate that in preschool-aged children, exposure to light before bedtime, even at low intensities, results in robust and sustained melatonin suppression," said Hartstein.

What parents can do

This does not necessarily mean that parents must throw away the nightlight and keep children in absolute darkness before bedtime. But at a time when half of children use screen media before bed, the research serves as a reminder to all parents to shut off the gadgets and keep light to a minimum to foster good sleep habits in their kids. Notably, a tablet at full brightness held 1 foot from the eyes in a dark room measures as much as 100 lux.

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Ancient Maya lessons on surviving drought

A new study casts doubt on drought as the driver of ancient Mayan civilization collapse.

There is no dispute that a series of droughts occurred in the Yucatan Peninsula of southeastern Mexico and northern Central America at the end of the ninth century, when Maya cities mysteriously began to be depopulated. Believing the Maya were mostly dependent on drought-sensitive corn, beans, and squash, some scholars assume the droughts resulted in starvation.

However, a new analysis by UC Riverside archaeologist Scott Fedick and plant physiologist Louis Santiago shows the Maya had nearly 500 edible plants available to them, many of which are highly drought resistant. The results of this analysis have now been published in the Proceedings of the National Academy of Sciences.

"Even in the most extreme drought situation -- and we have no clear evidence the most extreme situation ever occurred -- 59 species of edible plants would still have persisted," Santiago said.

Some of the toughest plants the Maya would have turned to include cassava with its edible tubers, and hearts of palm. Another is chaya, a shrub domesticated by the Maya and eaten today by their descendants. Its leaves are high in protein, iron, potassium, and calcium.

"Chaya and cassava together would have provided a huge amount of carbohydrates and protein," Santiago said.

Unable to find a master list of indigenous Maya food plants, Fedick recently compiled and published one that draws on decades of Maya plant knowledge. Faced with much speculation about drought as the cause of Maya social disruptions, he and Santiago decided to examine all 497 plants on the list for drought tolerance.

"When botanists study drought resistance, they're usually talking about a specific plant, or a particular ecosystem," Fedick said. "One of the reasons this project was so challenging is because we examined the dietary flora of an entire civilization -- annuals, perennials, herbs, trees, domesticates, and wild species. It was a unique endeavor."

Though the researchers do not have a clear answer about why ancient Maya society unraveled, they suspect social and economic upheaval played a role.

"One thing we do know is the overly simplistic explanation of drought leading to agricultural collapse is probably not true," Fedick said.

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Sauropod dinosaurs were restricted to warmer regions of Earth

Giant, long-necked sauropods, thought to include the largest land animals ever to have existed, preferred to live in warmer, more tropical regions on Earth, suggesting they may have had a different physiology from other dinosaurs, according to a new study led by researchers at UCL and the University of Vigo.

The study, published in the journal Current Biology, investigated the enigma of why sauropod fossils are only found at lower latitudes, while fossils of other main dinosaur types seem ubiquitously present, with many located in the polar regions.

The researchers analysed the fossil record across the Mesozoic era (the time of the dinosaurs), lasting from around 230 to 66 million years ago, looking at occurrences of fossils of the three main dinosaur types: sauropods, which include the Brontosaurus and the Diplodocus, theropods ("lizard-hipped"), which include velociraptors and Tyrannosaurus rex, and ornithischians ("bird-hipped") such as the Triceratops.

Combining this fossil data with data about climate throughout the period, along with information about how continents have moved across the globe, the researchers concluded that sauropods were restricted to warmer, drier habitats than other dinosaurs. These habitats were likely to be open, semi-arid landscapes, similar to today's savannahs.

Co-author Dr Philip Mannion (UCL Earth Sciences) said: "Our research shows that some parts of the planet always seemed to be too cold for sauropods. They seem to have avoided any temperatures approaching freezing. Other dinosaur types, in contrast, could thrive in Earth's polar regions, from innermost Antarctica to polar Alaska -- which, due to the warmer climate, were ice-free, with lush vegetation.

"This suggests sauropods had different thermal requirements from other dinosaurs, relying more on their external environment to heat their bodies -- slightly closer to being 'cold-blooded', like modern-day reptiles. Their grand size hints that this physiology may have been unique."

First author Dr Alfio Alessandro Chiarenza, formerly of UCL who is now based at the University of Vigo, Spain, said: "It may be that sauropods were physiologically incapable of thriving in colder regions, or that they thrived less well in these areas than their dinosaurian cousins and were outcompeted.

"A mix of features may have helped sauropods shed heat more easily than mammals do today. Their long necks and tails would have given them a larger surface area, and they may have had a respiratory system more akin to birds, which is much more efficient.

"Some species of theropods and ornithischians are known to have had feathers or downy fur helping them retain body warmth. This suggests they may have generated their own body heat. For sauropods, however, there is no evidence of this kind of insulation.

"Sauropods' strategies for keeping their eggs warm may also have differed from the other dinosaurs. Theropods probably warmed eggs by sitting on them, whereas ornithischians seem to have used heat generated by decaying plants. Sauropods, meanwhile, may have buried their eggs, relying on heat from the sun and the ground."

In their paper, the researchers noted that the fossil record showed zero occurrences of sauropods above a latitude of 50 degrees north -- an area encompassing most of Canada, Russia, northern Europe and the UK -- or below 65 degrees south, encompassing Antarctica. In contrast, there are rich records for theropods and ornithischians living above 50 degrees north in later periods (from 145 million years ago).

To test if this was a true reflection of where sauropods lived, researchers used a statistical technique to adjust for gaps in the fossil record, and also analysed where the highest diversities of dinosaur types were in different periods throughout the Mesozoic era.

They combined fossil data with climate data, allowing an estimate of the temperature ranges of the dinosaur types' habitats, finding that sauropods' range across the latitudes was more restricted during colder periods.

They then used habitat modelling to infer which regions of the globe would likely be suitable for sauropods and the other dinosaur types to live.

While in the past it was believed that dinosaurs were ectothermic ("cold-blooded"), like reptiles today, relying on the external environment to heat their bodies, it is now thought they were closer to "warm-blooded" mammals, generating some of their own body heat (endothermic).

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