“Our results support the idea that wakeful rest plays just as important a role as practice in learning a new skill. It appears to be the period when our brains compress and consolidate memories of what we just practiced,” said Leonardo G. Cohen, M.D., senior investigator at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS) and the senior author of the study published in Cell Reports. “Understanding this role of neural replay may not only help shape how we learn new skills but also how we help patients recover skills lost after neurological injury like stroke.”

The study was conducted at the NIH Clinical Center. Dr. Cohen’s team used a highly sensitive scanning technique, called magnetoencephalography, to record the brain waves of 33 healthy, right-handed volunteers as they learned to type a five-digit test code with their left hands. The subjects sat in a chair and under the scanner’s long, cone-shaped cap. An experiment began when a subject was shown the code “41234” on a screen and asked to type it out as many times as possible for 10 seconds and then take a 10 second break. Subjects were asked to repeat this cycle of alternating practice and rest sessions a total of 35 times.

During the first few trials, the speed at which subjects correctly typed the code improved dramatically and then leveled off around the 11th cycle. In a previous study, led by former NIH postdoctoral fellow Marlene Bönstrup, M.D., Dr. Cohen’s team showed that most of these gains happened during short rests, and not when the subjects were typing. Moreover, the gains were greater than those made after a night’s sleep and were correlated with a decrease in the size of brain waves, called beta rhythms. In this new report, the researchers searched for something different in the subjects’ brain waves.

“We wanted to explore the mechanisms behind memory strengthening seen during wakeful rest. Several forms of memory appear to rely on the replaying of neural activity, so we decided to test this idea out for procedural skill learning,” said Ethan R. Buch, Ph.D., a staff scientist on Dr. Cohen’s team and leader of the study.

To do this, Leonardo Claudino, Ph.D., a former postdoctoral fellow in Dr. Cohen’s lab, helped Dr. Buch develop a computer program which allowed the team to decipher the brain wave activity associated with typing each number in the test code.

The program helped them discover that a much faster version — about 20 times faster — of the brain activity seen during typing was replayed during the rest periods. Over the course of the first eleven practice trials, these compressed versions of the activity were replayed many times — about 25 times — per rest period. This was two to three times more often than the activity seen during later rest periods or after the experiments had ended.

Interestingly, they found that the frequency of replay during rest predicted memory strengthening. In other words, the subjects whose brains replayed the typing activity more often showed greater jumps in performance after each trial than those who replayed it less often.

“During the early part of the learning curve we saw that wakeful rest replay was compressed in time, frequent, and a good predictor of variability in learning a new skill across individuals,” said Dr. Buch. “This suggests that during wakeful rest the brain binds together the memories required to learn a new skill.”

As expected, the team discovered that the replay activity often happened in the sensorimotor regions of the brain, which are responsible for controlling movements. However, they also saw activity in other brain regions, namely the hippocampus and entorhinal cortex.

“We were a bit surprised by these last results. Traditionally, it was thought that the hippocampus and entorhinal cortex may not play such a substantive role in procedural memory. In contrast, our results suggest that these regions are rapidly chattering with the sensorimotor cortex when learning these types of skills,” said Dr. Cohen. “Overall, our results support the idea that manipulating replay activity during waking rest may be a powerful tool that researchers can use to help individuals learn new skills faster and possibly facilitate rehabilitation from stroke.”

The researchers demonstrated in a preclinical study that senolytic drugs significantly reduced mortality upon infection from a beta-coronavirus closely related to SARS-CoV-2 in older mice. The study published in Science was co-led by Laura Niedernhofer, MD, PhD and Paul Robbins, PhD, both professors in the Department of Biochemistry, Molecular Biology and Biophysics and co-directors of the Institute on the Biology of Aging and Metabolism at the U of M Medical School, and Sara Hamilton, PhD, assistant professor in the Department of Laboratory Medicine and Pathology.

Senescent cells — which are cells in the body that are damaged — contribute to inflammation, multiple chronic diseases and age-related loss of resilience, and they accumulate in our body as we age. Senolytic drugs, previously co-discovered by the U of M Medical School and the Mayo Clinic researchers, selectively remove senescent cells from the body.

The COVID-19 pandemic has revealed the pronounced vulnerability of the elderly and chronically-ill to morbidity and mortality induced by SARS-CoV-2. The research team sought to discover why older people are more vulnerable to these adverse outcomes. The team hypothesized it was senescent cells and removing them with senolytics would dial back inflammation and enable an improved response to viral infection.

“We wanted to determine if therapeutically targeting fundamental aging mechanisms, such as cellular senescence, could reduce morbidity and mortality following viral infection,” said Christina Camell, PhD, an assistant professor in the Department of Biochemistry, Molecular Biology and Biophysics, and a first author of the study.

The researchers found that older mice exposed for the first time to a mouse beta-coronavirus experienced nearly 100% mortality, whereas young mice barely got sick. When they treated the older mice with senolytic drugs following infection, their survival rate increased to 50%. The senolytic drugs reduced mortality, cellular senescence and inflammatory markers and increased anti-viral antibodies.

“We have been working on a new approach to help the elderly remain healthy, which is to find therapeutics to treat aging rather than treating each individual disease associated with old age. The fact that senolytics worked to protect old organisms from a viral infection proves that approach is accurate,” Robbins said. “By getting rid of a piece of aging biology, senescent cells, with senolytics, the older mice were able to withstand the stress of infection. This suggests that reducing the burden of senescent cells in ill or elderly individuals could improve their resilience and reduce their risk of dying from COVID-19.”

These results in mice supported the initiation of two clinical trials to reduce mortality in elderly COVID-19 patients. The team also plans to study if senescent cells contribute to the long-hauler effect in many COVID-19 survivors.

This work was supported by the National Institutes of Health, the University of Minnesota Clinical and Translational Science Institute, the University of Minnesota Medical School and the Medical Discovery Team on the Biology of Aging, The Irene Diamond Fund/American Federation on Aging Research Postdoctoral Transition Award, the Fesler-Lampert Chair in Aging Studies, the AFAR Junior Faculty Award, the Paul F. Glenn Center for Biology of Aging Research at Mayo Clinic, the Glenn Foundation, the Connor Fund, Robert J. and Theresa W. Ryan and the Noaber Foundation.

Story Source:

Materials provided by University of Minnesota Medical School. Original written by Kelly Glynn. Note: Content may be edited for style and length.

Not only are they rare (it’s estimated that less than 0.15 per cent of blue whales in the Southern Hemisphere survived whaling), they’re also reclusive by nature and can cover vast areas of ocean.

But now, a team of scientists led by UNSW Sydney are confident they’ve discovered a new population of pygmy blue whales, the smallest subspecies of blue whales, in the Indian Ocean.

And it was the whales’ powerful singing — recorded by underwater bomb detectors — that gave them away.

“We’ve found a whole new group of pygmy blue whales right in the middle of the Indian Ocean,” says UNSW Professor Tracey Rogers, marine ecologist and senior author of the study.

“We don’t know how many whales are in this group, but we suspect it’s a lot by the enormous number of calls we hear.”

The discovery was made possible using data from the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), an organisation that monitors international nuclear bomb testing.

Since 2002, the CTBTO have been using advanced underwater microphones (called ‘hydrophones’) to detect soundwaves from potential nuclear bomb tests. The recordings — which pick up many other detailed ocean sounds — are available to scientists to use for their marine science research.

The UNSW-led team were studying the data when they found an unusually strong signal: a whale song that had previously been identified in the recordings, but that scientists still knew little about. After closely studying its composition (details like the song’s structure, frequency and tempo), they realised that it belonged to a group of pygmy blue whales — but not any of the ones previously recorded in the area.

“I think it’s pretty cool that the same system that keeps the world safe from nuclear bombs allows us to find new whale populations, which long-term can help us study the health of the marine environment,” says Prof. Rogers.

Pygmy blue whales are the smallest members of the blue whale family, but that’s the only small thing about them: they can reach up to 24 metres’ long, which is almost the length of two standard buses.

If visual sightings confirm this new population, they would become the fifth population of pygmy blue whales to be discovered in the Indian Ocean.

The findings, recently published in Scientific Reports, have come in time for World Oceans Day.

“Blue whales in the Southern Hemisphere are difficult to study because they live offshore and don’t jump around — they’re not show-ponies like the humpback whales,” says Prof. Rogers.

“Without these audio recordings, we’d have no idea there was this huge population of blue whales out in the middle of the equatorial Indian Ocean.”

A chorus of whales

Dr Emmanuelle Leroy, the lead author of the study and former postdoctoral researcher at UNSW Science, is a bioacoustician — someone who studies how animals create and receive sounds. She was studying the CTBTO data when she noticed a peculiar pattern emerging.

“At first, I noticed a lot of horizontal lines on the spectrogram,” says Dr Leroy. “These lines at particular frequencies reflect a strong signal, so there was a lot of energy there.”

To find out if the signal was a random blip or something more, Dr Leroy and the team scanned 18 years’ worth of CTBTO data — the entire available dataset since the recording started — to look for any wider patterns.

They found the songs weren’t just a random occurrence.

“Thousands of these songs were being produced every year,” she says. “They formed a major part of the ocean’s acoustic soundscape.

“The songs couldn’t have just been coming from a couple of whales — they had to be from an entire population.”

Singing a simple tune

Like many other whales, blue whales are powerful singers: scientists estimate their songs can travel anywhere between 200 and 500 kilometres. These songs are very low frequency (barely audible to the human ear) and have a different structure to other whales’ songs.

“Humpback whales are like jazz singers,” says Prof. Rogers. “They change their songs all the time.

“Blue whales, on the other hand, are more traditional. They sing very structured, simple songs.”

Music style can even change within a whale species: each of the known pygmy blue whale populations in the Indian Ocean sing slightly different melodies. Prof. Rogers says these musical differences are similar to generational slang between humans.

“We still don’t know whether they’re born with their songs or whether they’ve learnt it,” she says.

“But it’s fascinating that within the Indian Ocean you have animals intersecting with one another all the time but whales from different regions still retain their distinctive songs. Their songs are like a fingerprint that allows us to track them as they move over thousands of kilometres.”

Dr Leroy compared the acoustic features of the song with the three other blue whale song-types known in the Indian Ocean, as well as with four types of Omura’s whale songs (another whale in the area) — but the evidence pointed towards this being an entirely new population of blue whales.

The team named the newly-found population ‘Chagos’, after the archipelago they were detected nearby.

“We suspect that the whales singing the Chagos song move at different times across the Indian Ocean,” says Prof. Rogers.

“We found them not only in the central Indian Ocean, but as far north as the Sri Lankan coastline and as far east in the Indian Ocean as the Kimberley coast in northern Western Australia.”

While the team are confident in their findings, Dr Leroy says it’s impossible to confirm the species without a visual observation. Visual sightings for such an elusive animal can be tricky and expensive to fund, so it’s unlikely this will be verified anytime soon.

“If it isn’t a blue whale, it definitely sings like one,” says Dr Leroy.

A big find for conservation

The finding is big news for marine conservation, as blue whales were brought to the edge of extinction after whaling in the 20th Century.

And unlike many other types of whales in the Southern Hemisphere, their numbers haven’t sprung back.

“Discovering a new population is the first step to protecting it,” says Dr Leroy.

Acoustic information hidden in whale songs can also teach us more about the animals, like their spatial distribution, migration patterns and population numbers. A previous study led by Dr Leroy even found the changing pitch of blue whales’ songs could be a response to the noise of cracking icebergs.

Prof. Rogers is now leading a team using the CTBTO data to study how the Chagos population has changed over time. The findings could teach us how the whales adapted to warming ocean temperatures over the past 18 years — and how they might fare moving into the future.

“The largest animal in the world is one of the hardest ones to actually study,” says Prof. Rogers.

“There are many more of these blue whales out there than we’ve realised — and we’ve only been able to find them with the help of this international infrastructure.”

For their analysis, the authors compiled information on African ape occurrence held in the IUCN SSC A.P.E.S. database, a repository that includes a remarkable amount of information on population status, threats and conservation for several hundred sites, collected over 20 years.

The first-of-its-kind study quantifies the joint effects of climate, land-use, and human population changes across African ape ranges for the year 2050 under best- and worst-case scenarios. “Best case” implies slowly declining carbon emissions and that appropriate mitigation measures will be put in place. “Worst case” assumes that emissions continue to increase unchecked — business as usual.

Under the best-case scenario, the authors predict that great apes will lose 85 percent of their range, of which 50 percent will be outside national parks and other areas protected by legislation. Under the worst-case scenario, they predict a 94 percent loss, of which 61 percent will be in areas that are not protected.

This paper examines whether great apes can or cannot disperse away from where they are currently found, and the best- and worst-case scenarios in each case. For example, mountains are currently less suitable than lowland areas for some great ape species. However, climate change will render some lowlands less suitable — warmer, drier, perhaps less food available — but the nearby mountains will take on the characteristics that those lowlands currently have. If great apes are able to physically move from the lowlands to the mountains, they may be able to survive, and even increase their range (depending on the species, and whether it is the best- or worst-case scenario). However, they may not be able to travel (disperse) away from the lowlands in the time remaining between today and 2050.

Joana Carvalho, postdoctoral researcher in the Faculty of Science, Liverpool John Moores University, lead author of the study says: “By integrating future climate and land-use changes as well as human population scenarios, this study provides strong evidence for synergistic interactions among key global drivers constraining African ape distribution.”

Carvalho adds: “Importantly, massive range loss is widely expected outside protected areas, which reflects the insufficiency of the current network of protected areas in Africa to preserve suitable habitats for great apes and effectively connect great ape populations.”

Fiona Maisels of the Wildlife Conservation Society (WCS), and a co-author of the study, said: “As climate change forces the different types of vegetation to essentially shift uphill, it means that all animals — not only great apes — that depend on particular habitat types will be forced to move uphill along with the vegetation, or become locally extinct. And when the hills are low, many species, great and small, will not be able go higher than the land allows, and huge numbers of animals and plants will simply vanish.”

The authors argue that effective conservation strategies require careful planning for each species that focuses on both existing and proposed protected areas — the creation and management of which can be informed by these habitat suitability models. Additionally, efforts to maintain connectivity between the habitats predicted to be suitable in the future will be crucial for the survival of African apes. Conservation planners urgently need to integrate land-use planning and climate change mitigation and adaptation measures into government policy of great ape range countries.

The study highlights the need for urgent action to combat both biodiversity loss and climate change if great apes are to continue into the future. Governments must protect and conserve the habitats of great apes — where they are now, and where they will need to move. Governments attending the upcoming Convention on Biological Diversity CoP 15 in September and the UN Climate Change Conference in November should adopt meaningful commitments to protect and conserve great apes and their habitats and combat climate change.

The results of the study corroborate other recent studies showing that African ape populations and their habitats are declining dramatically. All African great apes are classified either as Endangered (mountain gorillas, bonobos, Nigeria-Cameroon chimpanzees, eastern chimpanzees, and central chimpanzees) or Critically Endangered (Cross River gorillas, Grauer’s gorillas, western lowland gorillas, and western chimpanzees) on the IUCN Red List of Threatened Species, and all are regarded as flagship species for conservation.

Hjalmar Kuehl, from iDiv in Leipzig, Germany, and senior author of the study said: “There must be global responsibility for stopping the decline of great apes. Global consumption of natural resources extracted from ape range countries is a major driver of great ape decline. All nations benefitting from these resources have a responsibility to ensure a better future for great apes, their habitats and the people living therein by developing more sustainable economies.”