Intellectual disability is rarely inherited -- risk for younger siblings is low

 The prevalence of intellectual disabilities, which means difficulties with learning and understanding new things, is roughly 1-2% in the population. People with a severe intellectual disability need help from others in daily activities throughout their lives.

Such disabilities can be caused by genetic changes or external factors. According to estimates, roughly 2,500 genes underlie intellectual disability, of which approximately half remain unidentified.

In recent years, the diagnostics for intellectual disabilities have improved thanks to advancements in techniques that make it possible to sequence the entire genome. These techniques can also help to identify causes of intellectual disability not found in other medical examinations and tests. Exome sequencing, that is, the sequencing of the protein-coding regions of genes in the genome, enables the identification of new pathogenic gene variants as well. Identifying genes is a prerequisite for identifying disease mechanisms and developing treatments.

The study conducted at the University of Helsinki utilised exome sequencing to determine the potential genetic background of intellectual disability. The study participants included Finnish families with family members with delayed cognitive development for which no clear cause had been identified. The results were recently published in the Human Genetics journal.

It was found that in 64% of the study participants the cause of their developmental disorder was a known intellectual disability gene. The majority of these variants, 75%, was the result of random mutations taking place during fetal development (de novo), and variants not found in the parents' genome. An inherited mutation was identified in no more than a quarter of the pathogenic genes studied. More large-scale structural variants, which are usually not inherited, were found in only 8% of the families.

"Based on our findings, the risk of recurrence of intellectual disability in the next child of individual families is usually low," says Docent Irma Järvelä. According to Järvelä, this is a significant and relieving piece of information for many families.

She believes the use of exome sequencing as a primary method of examination in the diagnostics for intellectual disabilities is well justified. The technique makes it possible to investigate the cause of disability faster than before, which alleviates the uncertainty and concern felt by families, as well as generates savings in healthcare.

"The more familiar we are with the factors underlying intellectual disabilities and their hereditary nature, the better we are able to help families that encounter these serious disorders," Järvelä adds.

Human settlement history does not increase the prevalence of inherited diseases

The Finnish population has become known for its recessively inherited severe diseases caused by single gene defects known as founder variants, with some 40 of such diseases known so far.

The recently published study demonstrated that de novo variants created in early fetal development are the most common cause for intellectual disabilities also in the Finnish population. Known variants associated with recessive diseases were identified in only 5% of the families included in the study, a result in line with other European populations.

"In spite of the isolated nature of our population, Finns are not different from other European populations in terms of the inheritance of intellectual disabilities," Järvelä says.

A distant family connection going back 7 to 10 generations reduces the risk of establishing an recessively inherited disease even in small populations.

"In the light of contemporary gene research, the Finnish disease heritage appears an increasingly rare find. Related research in Finland is of a high medical standard," Järvelä emphasises.

In the recently published study, nine new candidate genes were identified, of which a handful were found to be recessive. In further research, one of these genes could turn out to be a previously unknown gene enriched in the Finnish population.

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What does the study of domesticated birds tell us about the evolution of human language?

Language is one of the most notable abilities humans have. It allows us to express complex meanings and transmit knowledge from generation to generation. An important question in human biology is how this ability ended up being developed, and researchers from the universities of Barcelona, Cologne and Tokyo have treated this issue in a recent article.

Published in the journal Trends in Cognitive Sciences, the article counts on the participation of the experts from the Institute of Complex Systems of the UB (UBICS) Thomas O'Rourke and Pedro Tiago Martins, led by Cedric Boeckx, ICREA research professor at the Faculty of Philology and Communication. According to the new study, the evolution of the language would be related to another notable feature of the Homo Sapiens: tolerance and human cooperation.

The study is based on evidence from diverse fields such as archaeology, evolutionary genomics, neurobiology, animal behaviour and clinical researcher on neuropsychiatric disorders. With these, it shows that the reduction of reactive aggressiveness, resulting from the evolution and process of self-domestication of our species, could have led to an increase in the complexity of speech. According to the authors, this development would be caused by the lowest impact on brain networks of stress hormones, neurotransmitters that activate in aggressive situations, and which would be crucial when learning to speak. To show this interaction, researchers analysed the genomic, neurobiological and singing-type differences between the domesticated Bengalese finch and its closest wild relative.

Looking for keys of the human language evolution in bird singing

A central aspect of the approach of the authors regarding the evolution of the language is that the aspects that make it special can be elucidated by comparing them to other animals' communication systems. "For instance, see how kids learn to talk and how birds learn to sing: unlike most animal communication systems, young birds' singing and the language of kids are only properly developed in presence of adult tutors. Without the vocal support from adults, the great range of sounds available for humans and singing birds does not develop properly," note researchers.

Moreover, although speaking and bird singing evolved independently, authors suggest both communication systems are associated with similar patterns in the brain connectivity and are negatively affected by stress: "Birds that are regularly under stress during their development sing a more stereotypical song as adults, while children with chronic stress problems are more susceptible to developing repetitive tics, including vocalizations in the case of Tourette syndrome."

In this context, Kazuo Okanoya, one of the authors of the article, has been studying the Bengalese finch (Lonchura striata domestica) for years. This domesticated singing bird sings a more varied and complex song than its wild ancestor. The study shows that the same happens with other domesticated species: the Bengalese finch has a weakened response to stress and is less aggressive than its wild relative. In fact, according to the authors, there is more and more "evidence of multiple domesticated species to have altered vocal repertoires compared to their wild counterparts."

The impact of domestication in stress and aggressiveness

For the researchers, these differences between domestic and wild animals are "the central pieces in the puzzle of the evolution of human language," since our species shares with other domestic animals particular physical changes related to their closest wild species. Modern humans have a plain face, a round skull and a reduced size of teeth compared to our extinct archaic relatives, Neanderthals. Domestic animals have comparable changes in facial and cranial bone structures, often accompanied by the development of other traits such as skin depigmentation, floppy ears and curly tails. Last, modern humans have marked reductions in the response measures to stress and reactive aggression compared to other living apes. These similarities do not stop with physical since, according to researchers, the genomes of modern humans and multiple domesticated species show changes focused on the same genes.

In particular, a disproportionate number of these genes would negatively regulate the activity of the glutamate neurotransmitter system, which drives the brain's response to stressful experiences. Authors note that "glutamate, the brain's main excitatory neurotransmitter, dopamine, in learning birdsong, aggressive behaviour, and the repetitive vocal tics of Tourette syndrome."

Alterations in stress hormone balance in the striated body

In the study, authors show how the activity of glutamate tends to promote the release of dopamine in the striated body, an evolutionary old brain structure important for learning which is based on rewards and motor activities. "In adult songbirds, the increase in dopamine release in this striatal area is correlated to the learning of a more restricted song, which replaces experimental vocalizations typical of young birds." "Regarding human beings and other mammals -authors add-, dopamine release in the dorsal striatum promotes restrictive and repetitive motor activities, such as vocalizations, while other more experimental and exploratory behaviours are supported by the dopaminergic activity of the ventral striatum." According to the study, many of the involved genes in the glutamatergic activation that changed in the recent human evolution, codify the signalling of receptors that reduce the excitation of the dorsal striatum. That is, these reduce the dopamine release in this area. Meanwhile, these receptors tend not to reduce, and even promote, the dopamine release in ventral striatal regions.

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Surprise twist suggests stars grow competitively

A survey of star formation activity in the Orion Nebula Cluster found similar mass distributions for newborn stars and dense gas cores, which may evolve into stars. Counterintuitively, this means that the amount of gas a core accretes as it develops, and not the initial mass of the core, is the key factor in deciding the final mass of the produced star.

The Universe is populated with stars of various masses. Dense cores in clouds of interstellar gas collapse under their own gravity to form stars, but what determines the final mass of the star remains an open question. There are two competing theories. In the core-collapse model, larger stars form from larger cores. In the competitive accretion model, all cores start out about the same mass but accrete different amounts of gas from the surroundings as they grow.

To distinguish between these two scenarios, a research team led by Hideaki Takemura at the National Astronomical Observatory of Japan created a map of the Orion Nebula Cluster where new stars are forming, based on data from the American CARMA interferometer and NAOJ's own Nobeyama 45-m Radio Telescope. Thanks to the unprecedent high resolution of the map, the team was able to compare the masses of the newly formed stars and gravitationally collapsing dense cores. They found that the mass distributions are similar for the two populations. They also found many smaller cores which don't have strong enough gravity to contract into stars.

One would think that similar mass distributions for prestellar cores and newborn stars would favor the core-collapse model, but actually because it is impossible for a core to impart all of its mass to a new star, this shows that continued gas inflow is an important factor, favoring the competitive accretion model.

Now the team will expand their map using additional data from CARMA and the Nobeyama 45-m Radio Telescope to see if the results from the Orion Nebula Cluster hold true for other regions.

From Science Daily

A new super-Earth detected orbiting a red dwarf star

In recent years there has been an exhaustive study of red dwarf stars to find exoplanets in orbit around them. These stars have effective surface temperatures between 2400 and 3700 K (over 2000 degrees cooler than the Sun), and masses between 0.08 and 0.45 solar masses. In this context, a team of researchers led by Borja Toledo Padrón, a Severo Ochoa-La Caixa doctoral student at the Instituto de Astrofísica de Canarias (IAC), specializing in the search for planets around this type of stars, has discovered a super-Earth orbiting the star GJ 740, a red dwarf star situated some 36 light years from Earth.

The planet orbits its star with a period of 2.4 days and its mass is around 3 times the mass of Earth. Because the star is so close to the Sun, and the planet so close to the star, this new super-Earth could be the object of future researches with very large diameter telescopes towards the end of this decade. The results of the study were recently published in the journal Astronomy & Astrophysics.

"This is the planet with the second shortest orbital period around this type of star. The mass and the period suggest a rocky planet, with a radius of around 1.4 Earth radii, which could be confirmed in future observations with the TESS satellite," explains Borja Toledo Padrón, the first author of the article. The data also indicate the presence of a second planet with an orbital period of 9 years, and a mass comparable to that of Saturn (close to 100 Earth masses), although its radial velocity signal could be due to the magnetic cycle of the star (similar to that of the Sun), so that more data are needed to confirm that the signal is really due to a planet.

The Kepler mission, recognised at one of the most successful in detecting exoplanets using the transit method (which is the search for small variations in the brightness of a star caused by the transit between it and ourselves of planets orbiting around it), has discovered a total of 156 new planets around cool stars. From its data it has been estimated that this type of stars harbours an average of 2.5 planets with orbital periods of less than 200 days. "The search for new exoplanets around cool stars is driven by the smaller difference between the planet's mass and the star's mass compared with stars in warmer spectral classes (which facilitates the detection of the planets' signals), as well as the large number of this type of stars in our Galaxy," comments Borja Toledo Padrón.

Cool stars are also an ideal target for the search for planets via the radial velocity method. This method is based on the detection of small variations in the velocity of a star due to the gravitational attraction of a planet in orbit around it, using spectroscopic observations. Since the discovery in 1998 of the first radial velocity signal of an exoplanet around a cool star, until now, a total of 116 exoplanets has been discovered around this class of stars using the radial velocity method. "The main difficulty of this method is related to the intense magnetic activity of this type of stars, which can produce spectroscopic signals very similar to those due to an exoplanet," says Jonay I. González Hernández, an IAC researcher who is a co-author of this article.

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The future of particle accelerators is here

When the Electron Ion Collider received the go-ahead in January 2020, it became the only new major accelerator in the works anywhere in the world.

"All the stars aligned," said Elke-Caroline Aschenauer, Brookhaven National Laboratory Staff Scientist and a leader in developing the EIC plans. "We have the technology to build this unique particle accelerator and detector to do the measurements that, together with the underlying theory, can for the first time provide answers to longstanding fundamental questions in nuclear physics."

The EIC isn't the only Brookhaven project poised to reshape nuclear and particle physics. Forthcoming data from the Relativistic Heavy Ion Collider could finally detect the elusive chiral magnetic effect. Meanwhile, planned accelerators could run on sustainable energy, a drastic departure from today's machines.

At a press conference during the 2021 APS April Meeting, researchers will discuss how cutting-edge accelerators could collide with both energy consumption and our assumptions about the nature of matter.

A powerful new facility for nuclear physics

"The scientific advances of the EIC will help us all to understand where we come from and how the visible matter around us is composed from its elementary building blocks," said Aschenauer.

The accelerator and detector will serve as a kind of camera, taking 3D images and movies of electrons colliding with polarized protons and ions. Like a CT scanner for atoms, the EIC will let scientists see how force-carrying gluon particles hold together quarks, the internal components of protons and neutrons. It will also offer insights into the spin of fundamental particles.

Aschenauer will give status updates from the first year of the EIC project -- a collaboration between BNL and Thomas Jefferson National Accelerator Facility -- and an overview of its experimental equipment.

Hunting for the chiral magnetic effect

The EIC will build on the Relativistic Heavy Ion Collider, which will soon produce major results of its own.

In summer 2021, data analysis will likely conclude on an experiment searching for decisive proof of the chiral magnetic effect. This proposed effect helps explain many fundamental features of the Standard Model and could unlock why our universe contains overwhelmingly more matter than antimatter, crucial to human existence.

Jinfeng Liao, a theoretical nuclear physicist at Indiana University Bloomington, will share key predictions about what the experiment might uncover.

"The signatures, as predicted by our theoretical study, show clear promise of unambiguously establishing the existence of chiral magnetic effect in the isobar collision experiment," said Liao.

Liao and colleagues created a custom fluid-dynamics-based computational tool to simulate experimental collisions and any changes the chiral magnetic effect would cause.

They show that the new experiment has a better chance of detecting the effect than previous attempts, long plagued by weak signals and strong background contamination. The predictions were published in Physical Review Letters.

Probing profound subatomic questions requires a lot of power.

"Large particle accelerators use a shockingly large amount of energy," said Georg Hoffstaetter, a professor at Cornell University.

He will share results from the Cornell-BNL Test Accelerator, or CBETA, the world's first to accelerate a beam multiple times while powering itself by reusing beam energy. It further reduces electricity demands with superconducting and magnetic equipment.

The Energy Recovery Linacs technology that enables the test accelerator could lead to smaller particle accelerators with higher beam currents and reduced energy consumption.

"People may benefit from the industrial applications of Energy Recovery Linacs by using better computer chips, by being cured in radiation therapy centers that guide beams with permanent magnets, or by inhaling accelerator-produced medical isotopes," said Hoffstaetter.

Building on the success of the test accelerator, its principal investigator and Brookhaven Senior Physicist Dejan Trbojevic will present designs for a new green energy collider. Particles speed along racetrack beam lines, formed from high-quality permanent magnets which require no use of electrical power.

"The 'green accelerator' shows a completely new way of accelerating particles with very tight control of their motion and with an extremely high energy range. It has never been done before," said Trbojevic.

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Study reveals how some antibodies can broadly neutralize ebolaviruses

Some survivors of ebolavirus outbreaks make antibodies that can broadly neutralize these viruses -- and now, scientists at Scripps Research have illuminated how these antibodies can disable the viruses so effectively. The insights may be helpful for developing effective therapies.

Ebolavirus is a family of often-deadly viruses that includes Ebola virus and many lesser-known viruses such as Bundibugyo virus, Sudan virus and Reston virus.

Structural biologists at Scripps Research used electron microscopy techniques to visualize a set of antibodies that target a key site on these viruses called the "glycan cap." Their research showed that the antibodies work against ebolaviruses using the same three mechanisms to prevent the virus from infecting host cells.

The research, published in Cell Reports, is a step toward the creation of an antibody-based treatment that will be useful against a broad range of ebolaviruses.

"We now understand the molecular basis for these antibodies' abilities to neutralize ebolviruses with broad reactivity against different viral species," says the study's first author Daniel Murin, PhD, a staff scientist in the laboratory of Andrew Ward, PhD.

Ward, a professor in the Department of Integrative Structural and Computational Biology at Scripps Research, says he hopes the work will contribute the development of a "cocktail" of therapeutic antibodies that can save lives by treating many forms of the Ebola virus.

"The goal is to provide doctors in Ebola-prone regions their best weapon yet against these deadly outbreaks," Ward says. "The insights we have gained through our structural studies of the virus show how this may be possible."

Ever-emergent Ebola

The first known ebolavirus, now called Zaire ebolavirus or simply Ebola virus, was identified in 1976, named for the site of an outbreak that year near the Ebola river in what was then Zaire and is now the Democratic Republic of Congo.

Other species have since been added to this family of viruses, including Sudan ebolavirus and Bundibugyo ebolavirus. Ebola viruses colonize African fruit bats, often cause disease in chimpanzees and other non-human primates, and trigger outbreaks in humans every few years, on average. Infected people develop a hemorrhagic syndrome that is fatal in roughly half of untreated cases.

Vaccines against Ebola have been developed recently but have not yet been widely used. And although antibody-based treatments also have been developed, none has been shown effective against a broad range of ebolavirus species.

Nevertheless, studies in recent years have shown that some survivors of Ebola infections carry antibodies that, in lab-dish tests, can neutralize multiple ebolavirus species. A surprisingly high proportion of these broadly neutralizing antibodies target the glycan cap, a sugar-slathered site on a stalk-like protein -- called the glycoprotein -- that enables Ebola viruses to enter host cells.

In the new study, Murin and Ward, along with their colleagues in the James Crowe Lab at Vanderbilt University where the antibodies were isolated, used electron microscopy to analyze a set of glycan cap-targeting antibodies from survivors of various ebolaviruses. Their aim was to understand better how these antibodies target the virus so effectively.

Three ways to defeat the virus

Their analysis suggested that the most broadly effective of these glycan cap-targeting antibodies hit the same vulnerable site on the glycan cap, allowing them to thwart viral infectivity in three ways.

First, the antibody displaces a long viral structure near the glycan cap in a way that destabilizes the entire viral glycoprotein structure, sometimes causing it to fall apart.

Second, the glycan cap antibody -- when it binds to its target site -- can block a key event in the infection process, in which an enzyme called a cathepsin cleaves off the glycan cap. Blocking this cleavage event blocks the glycoprotein's ability to enter host cells.

Finally, the glycan cap antibody, by displacing the loose structure near the glycan cap, enables another type of neutralizing antibody to bind to a separate vulnerable site on the virus. Thus, a glycan cap antibody can "synergize" with another antibody to hit the virus significantly harder than either antibody does alone.

The scientists also determined the key genetic elements that allow glycan-cap antibodies to thwart ebolaviruses in these three ways.

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Uncovering the secrets of some of the world's first color photographs

It is often said that before air travel our skies were bluer yet how, in the 21st century, could we ever know what light and colors were like one hundred years ago? Recently, a group of researchers from EPFL's Audiovisual Communications Laboratory, in the School of Computer and Communication Sciences (IC), had a unique opportunity to try to find out.

Normally hidden treasures locked away in the vaults of a handful of museums, the researchers were offered access to some of the original photographic plates and images of the scientist and inventor Gabriel Lippmann, who won the 1908 Nobel Prize in physics for his method of reproducing colors in photography.

In a paper just published in the Proceedings of the National Academy of Sciences (PNAS) the authors explain that most photographic techniques take just three measurements, for red, green and blue, however they discovered that Lippmann's historical approach typically captured 26 to 64 spectral samples of information in the visible region. His technique, based on the same interference principles that recently enabled gravitational waves to be detected and which is the foundation of holography and much of modern interferometric imaging, has been almost completely forgotten today.

"These are the earliest multi-spectral light measurements on record so we wondered whether it would be possible to accurately recreate the original light of these historical scenes," said Gilles Baechler, one of the paper's authors, "but the way the photographs were constructed was very particular so we were also really interested in whether we could create digital copies and understand how the technique worked."

The researchers found that the multi-spectral images reflected from a Lippmann plate contained distortions, although the reproduced colors looked accurate to the eye. When they examined the full spectrum reflected from a Lippmann plate, and compared it to the original, they measured a number of inconsistencies, many of which have never been documented, even in modern studies.

"We ended up modeling the full process from the multi-spectral image that you capture, all the way to recording it into the photograph. We were able to capture the light reflected back from it and measure how it differed from the original," explained Baechler. So, could the team replicate century old light?

"With the historic plates there are factors in the process that we just cannot know but because we understood how the light differed, we could create an algorithm to get back the original light that was captured. We were able to study invertibility, that is, given a spectrum produced by a Lippmann photograph we know it is possible to undo the distortions and reconstruct the original input spectrum. When we got our hands dirty and made our own plates using the historical process, we were able to verify that the modeling was correct," he continued.

While fully modeling a Nobel-prize-winning imaging technique is of significant interest in its own right, the researchers believe that revisiting Lippmann's photographic technique can inspire new technological developments this century.

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Coronavirus does not infect the brain but still inflicts damage, study finds

SARS-CoV-2, the virus that causes COVID-19, likely does not directly infect the brain but can still inflict significant neurological damage, according to a new study from neuropathologists, neurologists, and neuroradiologists at Columbia University Vagelos College of Physicians and Surgeons.

"There's been considerable debate about whether this virus infects the brain, but we were unable to find any signs of virus inside brain cells of more than 40 COVID-19 patients," says James E. Goldman, MD, PhD, professor of pathology & cell biology (in psychiatry), who led the study with Peter D. Canoll, MD, PhD, professor of pathology & cell biology, and Kiran T. Thakur, MD, the Winifred Mercer Pitkin Assistant Professor of Neurology.

"At the same time, we observed many pathological changes in these brains, which could explain why severely ill patients experience confusion and delirium and other serious neurological effects -- and why those with mild cases may experience 'brain fog' for weeks and months."

The study, published in the journal Brain, is the largest and most detailed COVID-19 brain autopsy report published to date, suggests that the neurological changes often seen in these patients may result from inflammation triggered by the virus in other parts of the body or in the brain's blood vessels.

No Virus in Brain Cells

The study examined the brains of 41 patients with COVID-19 who succumbed to the disease during their hospitalization. The patients ranged in age from 38 to 97; about half had been intubated and all had lung damage caused by the virus. Many of the patients were of Hispanic ethnicity. There was a wide range of hospital length with some patients dying soon after arrival to the emergency room while others remained in the hospital for months. All of the patients had extensive clinical and laboratory investigations, and some had brain MRI and CT scans.

To detect any virus in the neurons and glia cells of the brain, the researchers used multiple methods including RNA in situ hybridization, which can detect viral RNA within intact cells; antibodies that can detect viral proteins within cells; and RT-PCR, a sensitive technique for detecting viral RNA.

Despite their intensive search, the researchers found no evidence of the virus in the patients' brain cells. Though they did detect very low levels of viral RNA by RT-PCR, this was likely due to virus in blood vessels or leptomeninges covering the brain.

"We've looked at more brains than other studies, and we've used more techniques to search for the virus. The bottom line is that we find no evidence of viral RNA or protein in brain cells," Goldman says. "Though there are some papers that claim to have found virus in neurons or glia, we think that those result from contamination, and any virus in the brain is contained within the brain's blood vessels." "If there's any virus present in the brain tissue, it has to be in very small amounts and does not correlate with the distribution or abundance of neuropathological findings," Canoll says.

The tests were conducted on more than two dozen brain regions, including the olfactory bulb, which was searched because some reports have speculated that the coronavirus can travel from the nasal cavity into the brain via the olfactory nerve. "Even there, we didn't find any viral protein or RNA," Goldman says, "though we found viral RNA and protein in the patients' nasal mucosa and in the olfactory mucosa high in the nasal cavity." (The latter finding appears in an unpublished study, currently on BioRxiv, led by Jonathan Overdevest, MD, PhD, assistant professor of otolaryngology, and Stavros Lomvardas, PhD, professor of biochemistry & molecular biophysics and neuroscience.)

Hypoxic Damage and Signs of Neuronal Death

Despite the absence of virus in the brain, in every patient the researchers found significant brain pathology, which mostly fell into two categories.

"The first thing we noticed was a lot of areas with damage from a lack of oxygen," Goldman says. "They all had severe lung disease, so it's not surprising that there's hypoxic damage in the brain."

Some of these were large areas caused by strokes, but most were very small and only detectable with a microscope. Based on other features, the researchers believe these small areas of hypoxic damage were caused by blood clots, common in patients with severe COVID-19, that temporarily stopped the supply of oxygen to that area.

A more surprising finding, Goldman says, was the large number of activated microglia they found in the brains of most patients. Microglia are immune cells that reside in the brain and can be activated by pathogens.

"We found clusters of microglia attacking neurons, a process called 'neuronophagia,'" says Canoll. Since no virus was found in the brain, it's possible the microglia may have been activated by inflammatory cytokines, such as Interleukin-6, associated with SARS-CoV-2 infection.

"At the same time, hypoxia can induce the expression of 'eat me' signals on the surface of neurons, making hypoxic neurons more vulnerable to activated microglia," Canoll says, "so even without directly infecting brain cells, COVID-19 can cause damage to the brain."

The group found this pattern of pathology in one of their first autopsies, described by Osama Al-Dalahmah, MD, PhD, instructor in pathology & cell biology, in a case report published last March in Acta Neuropathologica Communications. Over the next few months, as the neuropathologists did many more COVID brain autopsies, they saw similar findings over and over again and realized that this is a prominent and common neuropathological finding in patients who die of COVID.

The activated microglia were found predominantly in the lower brain stem, which regulates heart and breathing rhythms, as well as levels of consciousness, and in the hippocampus, which is involved in memory and mood.

"We know the microglia activity will lead to loss of neurons, and that loss is permanent," Goldman says. "Is there enough loss of neurons in the hippocampus to cause memory problems? Or in other parts of the brain that help direct our attention? It's possible, but we really don't know at this point."

Persistent Neurological Problems in Survivors

Goldman says that more research is needed to understand the reasons why some post-COVID-19 patients continue to experience symptoms.

The researchers are now examining autopsies on patients who died several months after recovering from COVID-19 to learn more.

They are also examining the brains from patients who were critically ill with acute respiratory distress syndrome (ARDS) before the COVID-19 pandemic to see how much of COVID-19 brain pathology is a result of the severe lung disease.

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The light-bending dance of binary black holes

 A pair of orbiting black holes millions of times the Sun's mass perform a hypnotic pas de deux in a new NASA visualization. The movie traces how the black holes distort and redirect light emanating from the maelstrom of hot gas -- called an accretion disk -- that surrounds each one.

Viewed from near the orbital plane, each accretion disk takes on a characteristic double-humped look. But as one passes in front of the other, the gravity of the foreground black hole transforms its partner into a rapidly changing sequence of arcs. These distortions play out as light from both disks navigates the tangled fabric of space and time near the black holes.

"We're seeing two supermassive black holes, a larger one with 200 million solar masses and a smaller companion weighing half as much," said Jeremy Schnittman, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who created the visualization. "These are the kinds of black hole binary systems where we think both members could maintain accretion disks lasting millions of years."

The accretion disks have different colors, red and blue, to make it easier to track the light sources, but the choice also reflects reality. Hotter gas gives off light closer to the blue end of the spectrum, and material orbiting smaller black holes experiences stronger gravitational effects that produce higher temperatures. For these masses, both accretion disks would actually emit most of their light in the UV, with the blue disk reaching a slightly higher temperature.

Visualizations like this help scientists picture the fascinating consequences of extreme gravity's funhouse mirror. The new video doubles down on an earlier one Schnittman produced showing a solitary black hole from various angles.

Video: https://www.youtube.com/watch?v=rQcKIN9vj3U&t=1s

Seen nearly edgewise, the accretion disks look noticeably brighter on one side. Gravitational distortion alters the paths of light coming from different parts of the disks, producing the warped image. The rapid motion of gas near the black hole modifies the disk's luminosity through a phenomenon called Doppler boosting -- an effect of Einstein's relativity theory that brightens the side rotating toward the viewer and dims the side spinning away.

The visualization also shows a more subtle phenomenon called relativistic aberration. The black holes appear smaller as they approach the viewer and larger when moving away.

These effects disappear when viewing the system from above, but new features emerge. Both black holes produce small images of their partners that circle around them each orbit. Looking closer, it's clear that these images are actually edge-on views. To produce them, light from the black holes must be redirected by 90 degrees, which means we're observing the black holes from two different perspectives -- face on and edge on -- at the same time.

"A striking aspect of this new visualization is the self-similar nature of the images produced by gravitational lensing," Schnittman explained. "Zooming into each black hole reveals multiple, increasingly distorted images of its partner."

Schnittman created the visualization by computing the path taken by light rays from the accretion disks as they made their way through the warped space-time around the black holes. On a modern desktop computer, the calculations needed to make the movie frames would have taken about a decade. So Schnittman teamed up with Goddard data scientist Brian P. Powell to use the Discover supercomputer at the NASA Center for Climate Simulation. Using just 2% of Discover's 129,000 processors, these computations took about a day.

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Fast radio bursts shown to include lower frequency radio waves than previously detected

Since fast radio bursts (FRBs) were first discovered over a decade ago, scientists have puzzled over what could be generating these intense flashes of radio waves from outside of our galaxy. In a gradual process of elimination, the field of possible explanations has narrowed as new pieces of information are gathered about FRBs -- how long they last, the frequencies of the radio waves detected, and so on.

Now, a team led by McGill University researchers and members of Canada's CHIME Fast Radio Burst collaboration has established that FRBs include radio waves at frequencies lower than ever detected before, a discovery that redraws the boundaries for theoretical astrophysicists trying to put their finger on the source of FRBs.

"We detected fast radio bursts down to 110 MHz where before these bursts were only known to exist down to 300 MHz," explained Ziggy Pleunis, a postdoctoral researcher in McGill's Department of Physics and lead author of the research recently published in the Astrophysical Journal Letters. "This tells us that the region around the source of the bursts must be transparent to low-frequency emission, whereas some theories suggested that all low-frequency emission would be absorbed right away and could never be detected."

The study focussed on an FRB source first detected in 2018 by the CHIME radio telescope in British Columbia. Known as FRB 20180916B, the source has attracted particular attention because of its relative proximity to Earth and the fact that it emits FRBs at regular intervals.

The research team combined the capacities of CHIME with those of another radio telescope, LOFAR, or Low Frequency Array, in the Netherlands. The joint effort not only enabled the detection of the remarkably low FRB frequencies, but also revealed a consistent delay of around three days between the higher frequencies being picked up by CHIME and the lower ones reaching LOFAR.

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