A growing body of evidence supports the effectiveness of botulinum toxin injections in reducing the frequency of chronic migraine headaches, concludes an updated review and analysis in the January issue of Plastic and Reconstructive Surgery®.
Based on meta-analysis of pooled clinical trial data, botulinum toxin is superior to inactive placebo for preventive treatment of migraine, report Prof. Benoit Chaput, MD, PhD, of University Hospital Rangueil, Toulouse, France, and colleagues. "Botulinum toxin is a safe and well-tolerated treatment that should be proposed to patients with migraine," the researchers write.
Assembled Evidence Supports Effectiveness of Botox for Chronic Migraine
Prof. Chaput and colleagues identified and analyzed data from 17 previous randomized trials comparing botulinum toxin with placebo for preventive treatment of migraine headaches. Botulinum toxin -- best known by the brand name Botox -- was approved by the US Food and Drug Administration (FDA) for treatment of chronic migraine in 2010. Since then, a growing number of patients have reported successful results with botulinum toxin injections to alleviate chronic migraine headaches.
The 17 studies included nearly 3,650 patients, about 1,550 of whom had chronic migraine: defined as at least 15 headache attacks per month for more than three months, with migraine symptoms on at least eight days per month. The remaining patients had less-frequent episodic migraine headaches.
On pooled data analysis, botulinum toxin injections significantly reduced the frequency of chronic migraine attacks with. Three months after injection, patients treated with botulinum toxin had an average of 1.6 fewer migraine attacks per month, compared to those treated with inactive placebo.
The improvement was apparent within two months of botulinum toxin treatment. To sustain the effects of treatment, botulinum toxin injections are typically repeated every three months.
There was also a "statistical tendency" toward less-frequent attacks with botulinum toxin in patients with episodic migraine. Again, improvement occurred within two months. Although botulinum toxin had a higher rate of adverse effects compared to placebo, none of these were serious.
The pooled data also showed significant improvement in quality of life in patients treated with botulinum toxin. This improvement was directly linked to a reduction in depressive symptoms. "It can be explained by the reduced impact of headaches and migraine-related disability, thus reducing symptoms of depression and anxiety," Prof. Chaput and coauthors write.
Migraine headaches are an increasingly common condition, leading to significant disability and increased use of healthcare resources. Although botulinum toxin injection for chronic migraine is FDA-approved, there are still conflicting data regarding its effectiveness. The new report provides a comprehensive analysis of the highest-quality evidence to date, including three randomized trials not included in previous reports.
Read more at Science Daily
Jan 3, 2019
Scientists engineer shortcut for photosynthetic glitch, boost crop growth 40%
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| Four unmodified plants (left) grow beside four plants (right) engineered with alternate routes to bypass photorespiration -- an energy-expensive process that costs yield potential. The modified plants are able to reinvest their energy and resources to boost productivity by 40 percent. |
"We could feed up to 200 million additional people with the calories lost to photorespiration in the Midwestern U.S. each year," said principal investigator Donald Ort, the Robert Emerson Professor of Plant Science and Crop Sciences at Illinois' Carl R. Woese Institute for Genomic Biology. "Reclaiming even a portion of these calories across the world would go a long way to meeting the 21st Century's rapidly expanding food demands -- driven by population growth and more affluent high-calorie diets."
This landmark study is part of Realizing Increased Photosynthetic Efficiency (RIPE), an international research project that is engineering crops to photosynthesize more efficiently to sustainably increase worldwide food productivity with support from the Bill & Melinda Gates Foundation, the Foundation for Food and Agriculture Research (FFAR), and the U.K. Government's Department for International Development (DFID).
Photosynthesis uses the enzyme Rubisco -- the planet's most abundant protein -- and sunlight energy to turn carbon dioxide and water into sugars that fuel plant growth and yield. Over millennia, Rubisco has become a victim of its own success, creating an oxygen-rich atmosphere. Unable to reliably distinguish between the two molecules, Rubisco grabs oxygen instead of carbon dioxide about 20 percent of the time, resulting in a plant-toxic compound that must be recycled through the process of photorespiration.
"Photorespiration is anti-photosynthesis," said lead author Paul South, a research molecular biologist with the Agricultural Research Service, who works on the RIPE project at Illinois. "It costs the plant precious energy and resources that it could have invested in photosynthesis to produce more growth and yield."
Photorespiration normally takes a complicated route through three compartments in the plant cell. Scientists engineered alternate pathways to reroute the process, drastically shortening the trip and saving enough resources to boost plant growth by 40 percent. This is the first time that an engineered photorespiration fix has been tested in real-world agronomic conditions.
"Much like the Panama Canal was a feat of engineering that increased the efficiency of trade, these photorespiratory shortcuts are a feat of plant engineering that prove a unique means to greatly increase the efficiency of photosynthesis," said RIPE Director Stephen Long, the Ikenberry Endowed University Chair of Crop Sciences and Plant Biology at Illinois.
The team engineered three alternate routes to replace the circuitous native pathway. To optimize the new routes, they designed genetic constructs using different sets of promoters and genes, essentially creating a suite of unique roadmaps. They stress tested these roadmaps in 1,700 plants to winnow down the top performers.
Over two years of replicated field studies, they found that these engineered plants developed faster, grew taller, and produced about 40 percent more biomass, most of which was found in 50-percent-larger stems.
The team tested their hypotheses in tobacco: an ideal model plant for crop research because it is easier to modify and test than food crops, yet unlike alternative plant models, it develops a leaf canopy and can be tested in the field. Now, the team is translating these findings to boost the yield of soybean, cowpea, rice, potato, tomato, and eggplant.
"Rubisco has even more trouble picking out carbon dioxide from oxygen as it gets hotter, causing more photorespiration," said co-author Amanda Cavanagh, an Illinois postdoctoral researcher working on the RIPE project. "Our goal is to build better plants that can take the heat today and in the future, to help equip farmers with the technology they need to feed the world."
Read more at Science Daily
Melting ice sheets release tons of methane into the atmosphere
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| This photo shows a rhodamine dye injection into the proglacial river, just before a waterfall. The pink dye (the rhodamine) is used to calculate the water discharge of the proglacial river (i.e. how much water/melt if flowing in the river at that time). |
An international team of researchers led by the University of Bristol camped for three months next to the Greenland Ice Sheet, sampling the meltwater that runs off a large catchment (> 600 km2) of the Ice Sheet during the summer months.
As reported in Nature, using novel sensors to measure methane in meltwater runoff in real time, they observed that methane was continuously exported from beneath the ice.
They calculated that at least six tons of methane was transported to their measuring site from this portion of the Ice Sheet alone, roughly the equivalent of the methane released by up to 100 cows.
Professor Jemma Wadham, Director of Bristol's Cabot Institute for the Environment, who led the investigation, said: "A key finding is that much of the methane produced beneath the ice likely escapes the Greenland Ice Sheet in large, fast flowing rivers before it can be oxidized to CO2, a typical fate for methane gas which normally reduces its greenhouse warming potency."
Methane gas (CH4) is the third most important greenhouse gas in the atmosphere after water vapour and carbon dioxide (CO2). Although, present in lower concentrations that CO2, methane is approximately 20-28 times more potent. Therefore smaller quantities have the potential to cause disproportionate impacts on atmospheric temperatures. Most of the Earth's methane is produced by microorganisms that convert organic matter to CH4 in the absence of oxygen, mostly in wetlands and on agricultural land, for instance in the stomachs of cows and rice paddies. The remainder comes from fossil fuels like natural gas.
While some methane had been detected previously in Greenland ice cores and in an Antarctic Subglacial Lake, this is the first time that meltwaters produced in spring and summer in large ice sheet catchments have been reported to continuously flush out methane from the ice sheet bed to the atmosphere.
Lead author, Guillaume Lamarche-Gagnon, from Bristol's School of Geographical Sciences, said: "What is also striking is the fact that we've found unequivocal evidence of a widespread subglacial microbial system. Whilst we knew that methane-producing microbes likely were important in subglacial environments, how important and widespread they truly were was debatable. Now we clearly see that active microorganisms, living under kilometres of ice, are not only surviving, but likely impacting other parts of the Earth system. This subglacial methane is essentially a biomarker for life in these isolated habitats."
Most studies on Arctic methane sources focus on permafrost, because these frozen soils tend to hold large reserves of organic carbon that could be converted to methane when they thaw due to climate warming. This latest study shows that ice sheet beds, which hold large reserves of carbon, liquid water, microorganisms and very little oxygen -- the ideal conditions for creating methane gas -- are also atmospheric methane sources.
Co-researcher Dr Elizabeth Bagshaw from Cardiff University added: "The new sensor technologies that we used give us a window into this previously unseen part of the glacial environment. Continuous measurement of meltwater enables us to improve our understanding of how these fascinating systems work and how they impact the rest of the planet."
Read more at Science Daily
Archeological discovery yields clues to how our ancestors may have adapted to their environment
During the Stone Age ancestral humans lived with a variety of animal species along what was an area of wetlands in the middle of the Jordanian desert. The site, in the town of Azraq Basin, has been excavated and has revealed an abundance of tools and animal bones from up to 250,000 years ago, leading to better understanding of how ancestral humans have adapted to this changing environment.
James Pokines, PhD, associate professor of forensic anthropology at Boston University School of Medicine, was a leader of the excavation with a team from the Azraq Marshes Archaeological and Paleoecological Project.
The team discovered bone and tooth specimens belonging to wild ancestors of modern-day camels and elephants, as well as horse, rhinoceros, antelope and wild cattle species, among others. Poor preservation of small and less dense bones has resulted in limited conclusions about smaller species of animals that may have inhabited the area during this time.
Prior research in the site revealed evidence of butchery, with blood proteins from multiple species appearing on Stone Age tools. "The periphery of the wetlands where large animals drank and grazed would have presented excellent hunting opportunities for ancestral humans. Humans may have also faced their own challenges from other predatory competitors such as lions and hyenas roaming the area," said Pokines, corresponding author of the study.
The team's discovery adds important background to a growing picture of land use over time in Azraq Basin. "There are many portions of the globe that we still know so little about in terms of how ancestral humans lived and evolved there and how they adapted to that environment ... we hope to understand how different populations of ancestral humans adapted to this changing, arid environment throughout the Stone Age."
The excavation efforts were the outcome of a successful collaboration with Jordanian authorities and according to the researchers has paved the way for future excavations in the region.
From Science Daily
James Pokines, PhD, associate professor of forensic anthropology at Boston University School of Medicine, was a leader of the excavation with a team from the Azraq Marshes Archaeological and Paleoecological Project.
The team discovered bone and tooth specimens belonging to wild ancestors of modern-day camels and elephants, as well as horse, rhinoceros, antelope and wild cattle species, among others. Poor preservation of small and less dense bones has resulted in limited conclusions about smaller species of animals that may have inhabited the area during this time.
Prior research in the site revealed evidence of butchery, with blood proteins from multiple species appearing on Stone Age tools. "The periphery of the wetlands where large animals drank and grazed would have presented excellent hunting opportunities for ancestral humans. Humans may have also faced their own challenges from other predatory competitors such as lions and hyenas roaming the area," said Pokines, corresponding author of the study.
The team's discovery adds important background to a growing picture of land use over time in Azraq Basin. "There are many portions of the globe that we still know so little about in terms of how ancestral humans lived and evolved there and how they adapted to that environment ... we hope to understand how different populations of ancestral humans adapted to this changing, arid environment throughout the Stone Age."
The excavation efforts were the outcome of a successful collaboration with Jordanian authorities and according to the researchers has paved the way for future excavations in the region.
From Science Daily
What makes two species different?
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| The researchers use genetic markers to track segments of the X chromosome that they move from one species of Drosophila (fruit fly) into a different species in order to find X-linked genes that cause male sterility. Genetic markers that affect eye color are located on the X chromosome, so the researchers start with Drosophila mauritiana that have two genetic markers -- giving them dark red eyes, left -- and cross them to white-eyed Drosophila simulans. |
For most of the 20th century, scientists believed that this reproductive incompatibility evolved gradually between species as a by-product of adapting to different ecological circumstances: if two species were geographically isolated, they would adapt differences based on their environment. New research conducted at the University of Rochester, in collaboration with the University of Nebraska, shows, however, that there are more factors at play -- specifically the presence of selfish genes called meiotic drive elements, whose flow among species may dictate whether two species converge or diverge. In a new paper published in the journal eLife, the researchers show that sex chromosomes evolve to be genetically incompatible between species faster than the rest of the genetic chromosomes and reveal the factors at play in this incompatibility.
When two members of a species mate and exchange genetic material, this is known as gene flow. When two members of different species mate, however, gene flow is reduced. "Genes from one species simply can't talk to genes from the other species," says Daven Presgraves, a dean's professor of biology at Rochester. Though the genes may work fine on their own genetic background, when they are moved into the genetic background of another species, they have negative effects. "All of the gene copies in you and me work in the human genome. But if we were to take a gene out of you and stick it in a macaw parrot, they haven't seen this sequence before and it might not work together with the other genes. That would compromise some sort of function like fertility."
This is what happened when Presgraves and members of his lab crossed two different species of fruit flies, one from Madagascar and the other from the island of Mauritius. When the two species were crossed, their female hybrid offspring were fertile, but the hybrid male offspring were completely sterile. "One of the steps on the way to complete reproductive isolation is that the XY sex becomes sterile first in that gradual build-up of incompatibility," Presgraves says. In the case of fruit flies, as in human beings, the XY sex is male.
Chromosomes are divided into two types: allosomes, or sex chromosomes, and autosomes, or body chromosomes. Genetic traits linked to an organism's sex are passed on through the sex chromosomes. The rest of the genetic hereditary information is passed on through the autosomes. When the researchers mapped the factors that cause hybrid males to become sterile, they found that there were many more incompatibility factors on the X allosome compared to the autosomes. This means that sex chromosomes become functionally different between species much faster than non-sex chromosomes, Presgraves says. "There's a lot more exchange going on between the autosomes than on the X."
But what is it that makes sex chromosomes accumulate genetic incompatibility faster than the rest of the genome?
The researchers found that a class of "selfish genes" called meiotic drive elements are responsible for making sex chromosomes genetically incompatible at a faster rate. In general, selfish genes are parasites of the genome -- they propagate themselves at the expense of other genes. Meiotic drive elements in particular sabotage the rules of typical inheritance: in normal Mendelian inheritance, a gene is transmitted to half the offspring. Meiotic drive elements, however, manipulate reproduction so they can transmit themselves to more than their fair share of the genome. In hybrid male fruit flies, meiotic drive elements usually kill any sperm that don't carry them, leaving only (or mostly) sperm that do carry the meiotic drive elements.
"This could be because multiple meiotic drive elements from both parental species are unsuppressed in hybrids, and their combined action causes sterility," says Colin Meiklejohn, a former postdoctoral student in Presgraves's lab.
In a twist, however, the researchers also found that if meiotic drive elements are able to experience gene flow, they can also help bring species together. During early speciation, when two different species are just beginning to break away from one another, reproductive incompatibility can be incomplete and "leaky" -- some part of the genome may still be compatible and exchangeable.
"If two populations are leaky and there is opportunity for gene flow, a selfish gene can leak over into the other population and spread there," Presgraves says. If the species interbreeds and this selfish gene is able to be passed down, instead of becoming incompatible, "that part of the genome will become perfectly exchangeable. In some cases a selfish gene will basically erase the build-up of incompatibilities for a part of the genome."
Read more at Science Daily
Jan 2, 2019
Long term agriculture change impacts stream water quality
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| Graduate students Heather Luken and Tanner Williamson collect water samples from an automated sampler on Four Mile Creek. The autosampler collects a water sample from the stream every seven hours, and stores 24 samples in the carousel of bottles shown here. |
So, the USDA gave local farmers incentives to change some of their farming practices. One of these practices was conservation tillage, in which the soil is plowed less often. That can reduce sediment runoff.
A new study examines how the switch to conservation tillage has impacted Acton Lake over the past decades. From 1994 to 2014, the researchers measured concentrations of suspended sediment, nitrogen, and phosphorus in streams draining into Acton Lake.
"We find that short-term trends in water quality may not reflect long-term changes," says study co-author Michael Vanni.
Tracking changes in water quality over the long term is vital, says Vanni, a biologist at Miami University, Ohio. "We don't have a lot of long-term information on how water quality in a stream or lake responds to agricultural change," he says.
That might be surprising since many ecologists study agricultural watersheds. But according to Vanni, studies on a given ecosystem are usually short term. "Long-term studies, like ours, can reveal important shifts in water quality," says Vanni. "Many of the changes we observed can only be seen after studying the streams for 20 plus years."
Vanni and his colleagues found that water quality responses were different during the first decade of the study (1994-2003) compared to the next (2004-2014). They also discovered that concentrations of suspended sediment, nitrogen, and phosphorus each reacted differently.
Levels of suspended sediment declined throughout the entire study period. However, the decline was much sharper in the first ten years.
Phosphorus and nitrogen levels had contrasting outcomes. "The concentration of dissolved phosphorus in the streams declined sharply during the first ten years," says Vanni. "But then, phosphorus levels increased over the next ten years."
In contrast, nitrogen levels didn't change much in the first ten years. After that, they fell sharply.
The study focused on the watershed of the Upper Four Mile Creek, which drains into Acton Lake. Most of the surrounding area is made up of corn and soybean farms. The researchers have monitored farming practices in the area since 1989 and water quality since 1994.
The long-term changes seen in this study indicate that there might be tradeoffs in managing different aspects of water quality. "The main reason to encourage conservation tillage was to reduce soil erosion and sedimentation in Acton Lake," says Vanni. "That has clearly been successful. Sediment inputs to the lake have declined."
Nitrogen levels are also declining. "That's great for local freshwater ecosystems," says Vanni. "It's also beneficial to the Gulf of Mexico, where some of our runoff eventually travels."
On the other hand, rising phosphorus levels are a cause for concern. "They could promote algal blooms downstream," says Vanni. "We might need to consider the tradeoffs involved in managing for sediments, nitrogen, or phosphorus."
It's not completely clear how the study findings would apply to other areas. However, the changes in water quality observed in this study are similar to those seen in some of the rivers that drain into Lake Erie.
High phosphorus levels are a problem in those watersheds as well. In fact, "high levels of phosphorus are implicated in causing increased blooms of harmful algae in Lake Erie," says Vanni.
Vanni and colleagues hope to continue measuring changes in suspended sediments, nitrogen, and phosphorus in the Acton Lake watershed.
Read more at Science Daily
Early protostar already has a warped disk
Using observations from the ALMA radio observatory in Chile, researchers have observed, for the first time, a warped disk around an infant protostar that formed just several tens of thousands of years ago. This implies that the misalignment of planetary orbits in many planetary systems -- including our own -- may be caused by distortions in the planet-forming disk early in their existence.
The planets in our solar system orbit the sun in planes that are at most about seven degrees offset from the equator of the sun itself. It has been known for some time that many extrasolar systems have planets that are not lined up in a single plane or with the equator of the star. One explanation for this is that some of the planets might have been affected by collisions with other objects in the system or by stars passing by the system, ejecting them from their initial orbital plane.
However, the possibility remained that the formation of planets out of the normal plane was actually caused by a warping of the star-forming cloud out of which the planets were born. Recently, images of protoplanetary disks -- rotating disks where planets form around a star -- have in fact showed such warping. But it was still unclear how early this happened.
In the latest findings, published in Nature, the group from the RIKEN Cluster for Pioneering Research (CPR) and Chiba University in Japan have discovered that L1527; an infant protostar still embedded within a cloud, has a disk that has two parts -- an inner one rotating in one plane, and an outer one in a different plane. The disk is very young and still growing. L1527, which is about 450 light years away in the Taurus Molecular Cloud, is a good object for study as it has a disk that is nearly edge-on to our view.
According to Nami Sakai, who led the research group, "This observation shows that it is conceivable that the misalignment of planetary orbits can be caused by a warp structure formed in the earliest stages of planetary formation. We will have to investigate more systems to find out if this is a common phenomenon or not."
The remaining question is what caused the warping of the disk. Sakai suggests two reasonable explanations. "One possibility," she says, "is that irregularities in the flow of gas and dust in the protostellar cloud are still preserved and manifest themselves as the warped disk. A second possibility is that the magnetic field of the protostar is in a different plane from the rotational plane of the disk, and that the inner disk is being pulled into a different plane from the rest of the disk by the magnetic field." She says they plan further work to determine which is responsible for the warping of the disk.
The ALMA observatory in Chile is managed by an international consortium including the National Astronomical Observatory of Japan (NAOJ).
From Science Daily
The planets in our solar system orbit the sun in planes that are at most about seven degrees offset from the equator of the sun itself. It has been known for some time that many extrasolar systems have planets that are not lined up in a single plane or with the equator of the star. One explanation for this is that some of the planets might have been affected by collisions with other objects in the system or by stars passing by the system, ejecting them from their initial orbital plane.
However, the possibility remained that the formation of planets out of the normal plane was actually caused by a warping of the star-forming cloud out of which the planets were born. Recently, images of protoplanetary disks -- rotating disks where planets form around a star -- have in fact showed such warping. But it was still unclear how early this happened.
In the latest findings, published in Nature, the group from the RIKEN Cluster for Pioneering Research (CPR) and Chiba University in Japan have discovered that L1527; an infant protostar still embedded within a cloud, has a disk that has two parts -- an inner one rotating in one plane, and an outer one in a different plane. The disk is very young and still growing. L1527, which is about 450 light years away in the Taurus Molecular Cloud, is a good object for study as it has a disk that is nearly edge-on to our view.
According to Nami Sakai, who led the research group, "This observation shows that it is conceivable that the misalignment of planetary orbits can be caused by a warp structure formed in the earliest stages of planetary formation. We will have to investigate more systems to find out if this is a common phenomenon or not."
The remaining question is what caused the warping of the disk. Sakai suggests two reasonable explanations. "One possibility," she says, "is that irregularities in the flow of gas and dust in the protostellar cloud are still preserved and manifest themselves as the warped disk. A second possibility is that the magnetic field of the protostar is in a different plane from the rotational plane of the disk, and that the inner disk is being pulled into a different plane from the rest of the disk by the magnetic field." She says they plan further work to determine which is responsible for the warping of the disk.
The ALMA observatory in Chile is managed by an international consortium including the National Astronomical Observatory of Japan (NAOJ).
From Science Daily
Thriving on teamwork: New research shows how brain cells filter information in groups
When we perceive the world around us, certain objects appear to be more noticeable than others, depending on what we do. For example, when we view a forest-covered mountain from a distance, the forest looks like a large green carpet. But as we get closer, we start noticing the individual trees, and the forest fades to the background. What happens in the brain as our experience changes so drastically?
For decades, scientists studying the visual system thought that individual brain cells, called neurons, operate as filters. Some neurons would prefer coarse details of the visual scene and ignore fine details, while others would do the opposite. Every neuron was thought to do its own filtering.
A new study led by Salk Institute researchers challenges this view. The study revealed that the same neurons that prefer coarse details could change to prefer finer details under different conditions. The work, which appeared in the journal Neuron on December 31, 2018, could help to better understand neural mechanisms that shape our perceptions of the world.
"We were trying to look beneath the hood and figure out how these filters work," says Professor Thomas Albright, director of Salk's Center for Neurobiology of Vision and a senior author of the study.
"The selectivity of neurons was thought to be stable, but our work has shown that the filtering properties of neurons are much more flexible than was previously thought," adds study first author Ambarish Pawar, a postdoctoral researcher at Salk.
The team focused on neurons in the visual cortex in an animal model. Animals were shown optical patterns in which the researchers varied the contrast between dark and light areas and measured neurons' preferences to coarse and fine details. The goal was to see how neurons process these patterns, specifically in the brain's middle temporal area within the visual cortex. Scientists expected to find that the neurons were strictly "tuned" to perceive either coarse or fine details, but not both. What they found instead that an individual neuron could filter both fine as well as coarse detail, depending on the contrast of the pattern.
By measuring the firing rates of multiple neurons activated by the optical stimuli, the researchers showed that such flexibility was more likely if entire networks of neurons acted as filters rather than individual neurons.
"Our results suggest that the previously common description of individual neurons as filters was incorrect," says Sergei Gepshtein, a scientist with the Center for Neurobiology of Vision at Salk and co-author of the new study.
"The preference of neurons may shift due to a change in the balance of positive (excitatory) signals and negative (inhibitory) signals by which neurons communicate in the network," adds Pawar.
The researchers showed that teaming up endows networks of neurons with a high amount of flexibility in their preferences could easily adapt and tune the brain to the changing conditions, just as you might tune a radio to get good reception as you drive.
"We've uncovered a new dimension of adaptability of cortical networks," says Gepshtein. "Our results made it clear that to understand that adaptability we have to rethink what the computing units of the brain are. It is the team of connected neurons -- the malleable neural network -- that is more suited as such a unit rather than an individual neuron."
"This unexpected finding could help us shed light on the neural mechanisms that underlie the brains' enormous adaptability to a continuously changing environment," says Pawar.
Albright adds that, "even though the study centered on the visual system, this same flexible quality of neural networks is likely to hold true for other parts of the brain."
Read more at Science Daily
For decades, scientists studying the visual system thought that individual brain cells, called neurons, operate as filters. Some neurons would prefer coarse details of the visual scene and ignore fine details, while others would do the opposite. Every neuron was thought to do its own filtering.
A new study led by Salk Institute researchers challenges this view. The study revealed that the same neurons that prefer coarse details could change to prefer finer details under different conditions. The work, which appeared in the journal Neuron on December 31, 2018, could help to better understand neural mechanisms that shape our perceptions of the world.
"We were trying to look beneath the hood and figure out how these filters work," says Professor Thomas Albright, director of Salk's Center for Neurobiology of Vision and a senior author of the study.
"The selectivity of neurons was thought to be stable, but our work has shown that the filtering properties of neurons are much more flexible than was previously thought," adds study first author Ambarish Pawar, a postdoctoral researcher at Salk.
The team focused on neurons in the visual cortex in an animal model. Animals were shown optical patterns in which the researchers varied the contrast between dark and light areas and measured neurons' preferences to coarse and fine details. The goal was to see how neurons process these patterns, specifically in the brain's middle temporal area within the visual cortex. Scientists expected to find that the neurons were strictly "tuned" to perceive either coarse or fine details, but not both. What they found instead that an individual neuron could filter both fine as well as coarse detail, depending on the contrast of the pattern.
By measuring the firing rates of multiple neurons activated by the optical stimuli, the researchers showed that such flexibility was more likely if entire networks of neurons acted as filters rather than individual neurons.
"Our results suggest that the previously common description of individual neurons as filters was incorrect," says Sergei Gepshtein, a scientist with the Center for Neurobiology of Vision at Salk and co-author of the new study.
"The preference of neurons may shift due to a change in the balance of positive (excitatory) signals and negative (inhibitory) signals by which neurons communicate in the network," adds Pawar.
The researchers showed that teaming up endows networks of neurons with a high amount of flexibility in their preferences could easily adapt and tune the brain to the changing conditions, just as you might tune a radio to get good reception as you drive.
"We've uncovered a new dimension of adaptability of cortical networks," says Gepshtein. "Our results made it clear that to understand that adaptability we have to rethink what the computing units of the brain are. It is the team of connected neurons -- the malleable neural network -- that is more suited as such a unit rather than an individual neuron."
"This unexpected finding could help us shed light on the neural mechanisms that underlie the brains' enormous adaptability to a continuously changing environment," says Pawar.
Albright adds that, "even though the study centered on the visual system, this same flexible quality of neural networks is likely to hold true for other parts of the brain."
Read more at Science Daily
Juno mission captures images of volcanic plumes on Jupiter's moon Io
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| Juno's Radiation Monitoring Investigation collected this image of Jupiter's moon Io with Juno's Stellar Reference Unit (SRU) star camera shortly after Io was eclipsed by Jupiter at 12:40:29 (UTC) Dec. 21, 2018. Io is softly illuminated by moonlight from another of Jupiter's moons, Europa. The brightest feature on Io is suspected to be a penetrating radiation signature. The glow of activity from several of Io's volcanoes is seen, including a plume circled in the image. |
"We knew we were breaking new ground with a multi-spectral campaign to view Io's polar region, but no one expected we would get so lucky as to see an active volcanic plume shooting material off the moon's surface," said Scott Bolton, principal investigator of the Juno mission and an associate vice president of Southwest Research Institute's Space Science and Engineering Division. "This is quite a New Year's present showing us that Juno has the ability to clearly see plumes."
JunoCam acquired the first images on Dec. 21 at 12:00, 12:15 and 12:20 coordinated universal time (UTC) before Io entered Jupiter's shadow. The Images show the moon half-illuminated with a bright spot seen just beyond the terminator, the day-night boundary.
"The ground is already in shadow, but the height of the plume allows it to reflect sunlight, much like the way mountaintops or clouds on the Earth continue to be lit after the sun has set," explained Candice Hansen-Koharcheck, the JunoCam lead from the Planetary Science Institute.
At 12:40 UTC, after Io had passed into the darkness of total eclipse behind Jupiter, sunlight reflecting off nearby moon Europa helped to illuminate Io and its plume. SRU images released by SwRI depict Io softly illuminated by moonlight from Europa. The brightest feature on Io in the image is thought to be a penetrating radiation signature, a reminder of this satellite's role in feeding Jupiter's radiation belts, while other features show the glow of activity from several volcanoes. "As a low-light camera designed to track the stars, the SRU can only observe Io under very dimly lit conditions. Dec. 21 gave us a unique opportunity to observe Io's volcanic activity with the SRU using only Europa's moonlight as our lightbulb," said Heidi Becker, lead of Juno's Radiation Monitoring Investigation, at NASA's Jet Propulsion Laboratory.
Sensing heat at long wavelengths, the JIRAM instrument detects hotspots in the daylight and at night.
"Though Jupiter's moons are not JIRAM's primary objectives, every time we pass close enough to one of them, we take advantage of the opportunity for an observation," said Alberto Adriani, a researcher at Italy's National Institute of Astrophysics. "The instrument is sensitive to infrared wavelengths, which are perfect to study the volcanism of Io. This is one of the best images of Io that JIRAM has been able to collect so far."
The latest images can lead to new insights into the gas giant's interactions with its five moons, causing phenomena such as Io's volcanic activity or freezing of the moon's atmosphere during eclipse, added Bolton. JIRAM recently documented Io's volcanic activity before and after eclipse. Io's volcanoes were discovered by NASA's Voyager spacecraft in 1979. Io's gravitational interaction with Jupiter drives the moon's volcanoes, which emit umbrella-like plumes of SO2 gas and produce extensive basaltic lava fields.
The recent Io images were captured at the halfway point of the mission, which is scheduled to complete a map of Jupiter in July 2021. Launched in 2011, Juno arrived at Jupiter in 2016. The spacecraft orbits Jupiter every 53 days, studying its auroras, atmosphere and magnetosphere.
Read more at Science Daily
New Horizons successfully explores Ultima Thule
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| At left is a composite of two images taken by New Horizons' high-resolution Long-Range Reconnaissance Imager (LORRI), which provides the best indication of Ultima Thule's size and shape so far. Preliminary measurements of this Kuiper Belt object suggest it is approximately 20 miles long by 10 miles wide (32 kilometers by 16 kilometers). An artist's impression at right illustrates one possible appearance of Ultima Thule, based on the actual image at left. The direction of Ultima's spin axis is indicated by the arrows. |
"Congratulations to NASA's New Horizons team, Johns Hopkins Applied Physics Laboratory and the Southwest Research Institute for making history yet again. In addition to being the first to explore Pluto, today New Horizons flew by the most distant object ever visited by a spacecraft and became the first to directly explore an object that holds remnants from the birth of our solar system," said NASA Administrator Jim Bridenstine. "This is what leadership in space exploration is all about."
Signals confirming the spacecraft is healthy and had filled its digital recorders with science data on Ultima Thule reached the mission operations center at the Johns Hopkins Applied Physics Laboratory (APL) today at 10:29 a.m. EST, almost exactly 10 hours after New Horizons' closest approach to the object.
"New Horizons performed as planned today, conducting the farthest exploration of any world in history -- 4 billion miles from the Sun," said Principal Investigator Alan Stern, of the Southwest Research Institute in Boulder, Colorado. "The data we have look fantastic and we're already learning about Ultima from up close. From here out the data will just get better and better!"
Images taken during the spacecraft's approach -- which brought New Horizons to within just 2,200 miles (3,500 kilometers) of Ultima at 12:33 a.m. EST -- revealed that the Kuiper Belt object may have a shape similar to a bowling pin, spinning end over end, with dimensions of approximately 20 by 10 miles (32 by 16 kilometers). Another possibility is Ultima could be two objects orbiting each other. Flyby data have already solved one of Ultima's mysteries, showing that the Kuiper Belt object is spinning like a propeller with the axis pointing approximately toward New Horizons. This explains why, in earlier images taken before Ultima was resolved, its brightness didn't appear to vary as it rotated. The team has still not determined the rotation period.
As the science data began its initial return to Earth, mission team members and leadership reveled in the excitement of the first exploration of this distant region of space.
"New Horizons holds a dear place in our hearts as an intrepid and persistent little explorer, as well as a great photographer," said Johns Hopkins Applied Physics Laboratory Director Ralph Semmel. "This flyby marks a first for all of us -- APL, NASA, the nation and the world -- and it is a great credit to the bold team of scientists and engineers who brought us to this point."
"Reaching Ultima Thule from 4 billion miles away is an incredible achievement. This is exploration at its finest," said Adam L. Hamilton, president and CEO of the Southwest Research Institute in San Antonio. "Kudos to the science team and mission partners for starting the textbooks on Pluto and the Kuiper Belt. We're looking forward to seeing the next chapter."
The New Horizons spacecraft will continue downloading images and other data in the days and months ahead, completing the return of all science data over the next 20 months. When New Horizons launched in January 2006, George W. Bush was in the White House, Twitter had just been launched and Time Magazine's Person of the Year was "you -- all the worldwide web users." Nine years into its journey, the spacecraft began its exploration of the Kuiper Belt with a flyby of Pluto and its moons. Almost 13 years after the launch, the spacecraft will continue its exploration of the Kuiper Belt until at least 2021. Team members plan to propose more Kuiper Belt exploration.
Read more at Science Daily
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