Researchers also found that supplementing the processed diet with the omega-3 fatty acid DHA prevented memory problems and reduced the inflammatory effects almost entirely in older rats.

Neuroinflammation and cognitive problems were not detected in young adult rats that ate the processed diet.

The study diet mimicked ready-to-eat human foods that are often packaged for long shelf lives, such as potato chips and other snacks, frozen entrees like pasta dishes and pizzas, and deli meats containing preservatives.

Highly processed diets are also associated with obesity and type 2 diabetes, suggesting older consumers might want to scale back on convenience foods and add foods rich in DHA, such as salmon, to their diets, researchers say — especially considering harm to the aged brain in this study was evident in only four weeks.

“The fact we’re seeing these effects so quickly is a little bit alarming,” said senior study author Ruth Barrientos, an investigator in The Ohio State University Institute for Behavioral Medicine Research and associate professor of psychiatry and behavioral health.

“These findings indicate that consumption of a processed diet can produce significant and abrupt memory deficits — and in the aging population, rapid memory decline has a greater likelihood of progressing into neurodegenerative diseases such as Alzheimer’s disease. By being aware of this, maybe we can limit processed foods in our diets and increase consumption of foods that are rich in the omega-3 fatty acid DHA to either prevent or slow that progression.”

The research is published in the journal Brain, Behavior, and Immunity.

Barrientos’ lab studies how everyday life events — such as surgery, an infection or, in this case, an unhealthy diet — might trigger inflammation in the aging brain, with a specific focus on the hippocampus and amygdala regions. This work builds on her previous research suggesting a short-term, high-fat diet can lead to memory loss and brain inflammation in older animals, and that DHA levels are lower in the hippocampus and amygdala of the aged rat brain.

DHA, or docosahexaenoic acid, is an omega-3 fatty acid that is present along with eicosapentaenoic acid (EPA) in fish and other seafood. Among DHA’s multiple functions in the brain is a role in fending off an inflammatory response — this is the first study of its ability to act against brain inflammation brought on by a processed diet.

The research team randomly assigned 3-month-old and 24-month-old male rats to their normal chow (32% calories from protein, 54% from wheat-based complex carbs and 14% from fat), a highly processed diet (19.6% of calories from protein, 63.3% from refined carbs — cornstarch, maltodextrin and sucrose — and 17.1% from fat), or the same processed diet supplemented with DHA.

Activation of genes linked to a powerful pro-inflammatory protein and other markers of inflammation was significantly elevated in the hippocampus and amygdala of the older rats that ate the processed diet alone compared to young rats on any diet and aged rats that ate the DHA-supplemented processed food.

The older rats on the processed diet also showed signs of memory loss in behavioral experiments that weren’t evident in the young rats. They forgot having spent time in an unfamiliar space within a few days, a sign of problems with contextual memory in the hippocampus, and did not display anticipatory fear behavior to a danger cue, which suggested there were abnormalities in the amygdala.

“The amygdala in humans has been implicated in memories associated with emotional — fear and anxiety-producing — events. If this region of the brain is dysfunctional, cues that predict danger may be missed and could lead to bad decisions,” Barrientos said.

The results also showed that DHA supplementation of the processed-food diets consumed by the older rats effectively prevented the elevated inflammatory response in the brain as well as behavioral signs of memory loss.

Researchers don’t know the exact dosage of DHA — or precise calories and nutrients — taken in by the animals, which all had unlimited access to food. Both age groups gained a significant amount of weight on the processed diet, with old animals gaining significantly more than the young animals. DHA supplementation had no preventive effect on weight gain associated with eating highly processed foods.

That was a key finding: Barrientos cautioned against interpreting the results as a license for consumers to feast on processed foods as long as they take a DHA supplement. A better bet to prevent multiple negative effects of highly refined foods would be focusing on overall diet improvement, she said.

“These are the types of diets that are advertised as being low in fat, but they’re highly processed. They have no fiber and have refined carbohydrates that are also known as low-quality carbohydrates,” she said. “Folks who are used to looking at nutritional information need to pay attention to the fiber and quality of carbohydrates. This study really shows those things are important.”

This research was supported by the National Institute on Aging, the National Institute of Dental and Craniofacial Research, and the Ohio Agricultural Research and Development Center. Co-authors include Michael Butler, Nicholas Deems, Stephanie Muscat and Martha Belury from Ohio State and Christopher Butt of Inotiv Inc. in Boulder, Colorado.

Now, Salk researchers have discovered how neurons in a small area of the mammalian brain help filter distracting or disruptive signals — specifically from the hands — to coordinate dexterous movements. Their results, published in the journal Science on October 14, 2021, may hold lessons in how the brain filters other sensory information as well.

“These findings have implications not only for gaining a better understanding of how our nervous system interacts with the world, but also for teaching us how to build better prosthetics and robots, and how to more effectively repair neural circuitry after disease or injury,” says Eiman Azim, assistant professor in Salk’s Molecular Neurobiology Laboratory and the William Scandling Developmental Chair.

Scientists have long known that input from the hands is needed to coordinate dexterous movements, from throwing a ball to playing a musical instrument. In one classic experiment, volunteers with anesthetized, numb fingertips found it extremely difficult to pick up and light a match.

“There’s a common misconception that the brain sends a signal and you just perform the resulting movement,” says Azim. “But in reality, the brain is constantly incorporating feedback information about the state of your limbs and fingers and adjusting its output in response.”

If the brain responded to every signal from the body, it would quickly become overwhelmed — as happens with some sensory processing disorders. Azim and his colleagues wanted to identify exactly how a healthy brain manages to pick and choose which tactile signals to take into account to coordinate dexterous movements like manipulating objects.

They used a combination of tools in mice to study cells within a small area in the brainstem called the cuneate nucleus, which is the first area signals from the hand enter the brain. While it was known that sensory information passes through the cuneate nucleus, the team discovered that a set of neurons in this region actually controls how much information from the hands eventually passes on to other parts of the brain. By manipulating those circuits to allow more or less tactile feedback through, Azim’s team could influence how mice perform dexterous tasks — such as pulling a rope or learning to distinguish textures — to earn rewards.

“The cuneate nucleus is often referred to as a relay station, as if information was just passing through it,” says Staff Researcher James Conner, first author of the new paper. “But it turns out that sensory information is actually being modulated in this structure.”

Conner and Azim went on to show how different parts of the cortex in mice — the region responsible for more complex, adaptive behavior — can in turn control the neurons of the cuneate to dictate how strongly they’re filtering sensory information from the hands.

Today, despite decades of work, most prosthetics and robots struggle to be nimble-fingered and carry out small, precise hand movements. Azim and Conner say their work could help inform the design of better processes to integrate sensory information from artificial fingers into these kinds of systems to improve their dexterity. It also could have implications for understanding sensory processing disorders or troubleshooting what goes wrong in the brain when the flow of sensory information is thrown out of balance.

“Sensory systems have evolved to have very high sensitivity in order to maximize protective responses to external threats. But our own actions can activate these sensory systems, thereby generating feedback signals that can be disruptive to our intended actions,” says Conner.

“We’re constantly bombarded with information from the world, and the brain needs ways to decide what comes through and what doesn’t,” says Azim. “It’s not just tactile feedback, but visual and olfactory and auditory, temperature and pain — the lessons we’re learning about this circuitry likely apply in general ways to how the brain modulates these types of feedback as well.”

Other authors included Andrew Bohannon, Masakazu Igarashi, James Taniguchi and Nicholas Baltar of Salk.

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Stars and planets are formed from the same cosmic gas and dust. In the course of the formation process, some of the material condenses and forms rocky planets, the rest is either accumulated by the star or becomes part of gaseous planets. The assumption of a connection between the composition of stars and their planets is therefore reasonable and is confirmed, for example, in the solar system by most rocky planets (Mercury being the exception). Nevertheless, assumptions, especially in astrophysics, do not always prove to be true. A study led by the Instituto de Astrofísica e Ciências do Espaço (IA) in Portugal, which also involves researchers from the NCCR PlanetS at the University of Bern and the University of Zürich, published today in the journal Science, provides the first empirical evidence for this assumption — and at the same time partially contradicts it.

Condensed star vs rocky planet

To determine whether the compositions of stars and their planets are related, the team compared very precise measurements of both. For the stars, their emitted light was measured, which bears the characteristic spectroscopic fingerprint of their composition. The composition of the rocky planets was determined indirectly: Their density and composition were derived from their measured mass and radius. Only recently have enough planets been measured so precisely that meaningful investigations of this kind are possible.

“But since stars and rocky planets are quite different in nature, the comparison of their composition is not straightforward,” as Christoph Mordasini, co-author of the study, lecturer of astrophysics at the university of Bern and member of the NCCR PlanetS begins to explain. “Instead, we compared the composition of the planets with a theoretical, cooled-down version of their star. While most of the star’s material — mainly hydrogen and helium — remains as a gas when it cools, a tiny fraction condenses, consisting of rock-forming material such as iron and silicate,” explains Christoph Mordasini.

At the University of Bern, the “Bern Model of Planet Formation and Evolution” has been continuously developed since 2003 (see infobox). Christoph Mordasini says: “Insights into the manifold processes involved in the formation and evolution of planets are integrated into the model.” Using this Bern model the researchers were able to calculate the composition of this rock-forming material of the cooled-down star. “We then compared that with the rocky planets,” Christoph Mordasini says.

Indications of the habitability of planets

“Our results show that our assumptions regarding star and planet compositions were not fundamentally wrong: the composition of rocky planets is indeed intimately tied to the composition of their host star. However, the relationship is not as simple as we expected,” lead author of the study and researcher at the IA, Vardan Adibekyan, says. What the scientists expected, was that the star’s abundance of these elements sets the upper possible limit. “Yet for some of the planets, the iron abundance in the planet is even higher than in the star” as Caroline Dorn, who co-authored the study and is a member of the NCCR PlanetS as well as Ambizione Fellow at the University of Zurich, explains. “This could be due to giant impacts on these planets that break off some of the outer, lighter materials, while the dense iron core remains,” according to the researcher. The results could therefore give the scientists clues about the history of the planets.

“The results of this study are also very useful to constrain planetary compositions that are assumed based on the calculated density from mass and radius measurements,” Christoph Mordasini explains. “Since more than one composition can fit a certain density, the results of our study tell us that we can narrow potential compositions down, based on the host star’s composition,” Mordasini says. And since the exact composition of a planet influences, for example, how much radioactive material it contains or how strong its magnetic field is, it can determine whether the planet is life-friendly or not.

“Bern Model of Planet Formation and Evolution”

Statements can be made about how a planet was formed and how it has evolved using the “Bern Model of Planet Formation and Evolution.” The Bern model has been continuously developed at the University of Bern since 2003. Insights into the manifold processes involved in the formation and evolution of planets are integrated into the model. These are, for example, submodels of accretion (growth of a planet’s core) or of how planets interact gravitationally and influence each other, and of processes in the protoplanetary disks in which planets are formed. The model is also used to create so-called population syntheses, which show which planets develop how frequently under certain conditions in a protoplanetary disk.

The international study paints an even grimmer picture of a global nuclear war’s aftermath than previous analyses. The research team used newly developed computer climate modeling techniques to learn more about the effects of a hypothetical nuclear exchange, including complex chemistry interactions in the stratosphere that influence the amounts of ultraviolet (UV) radiation that reach the planet’s surface.

“In addition to all the fatalities that would happen almost immediately, the climate effects and the UV effects would be widespread,” said lead author Charles Bardeen, a scientist at the National Center for Atmospheric Research (NCAR). “These aren’t local to where the war occurs. They’re global, so they would affect all of us.”

Bardeen and his co-authors found that smoke from a global nuclear war would destroy much of the ozone layer over a 15-year period, with the ozone loss peaking at an average of about 75% worldwide. Even a regional nuclear war would lead to a peak ozone loss of 25% globally, with recovery taking about 12 years.

Since the ozone layer protects Earth’s surface from harmful UV radiation, such impacts would be devastating to humans and the environment. High levels of UV radiation have been linked to certain types of skin cancer, cataracts, and immunological disorders. The ozone layer also protects terrestrial and aquatic ecosystems, as well as agriculture.

“Although we suspected that ozone would be destroyed after nuclear war and that would result in enhanced ultraviolet light at the Earth’s surface, if there was too much smoke, it would block out the ultraviolet light,” said study co-author Alan Robock, a professor of climate science at Rutgers University. “Now, for the first time, we have calculated how this would work and quantified how it would depend on the amount of smoke.”

The study was funded by the Open Philanthropy Project with computational support from the National Science Foundation, which is NCAR’s sponsor, as well as from the University of Colorado Boulder and Colorado State University. It was published in the Journal of Geophysical Research — Atmospheres, a publication of the American Geophysical Union.

Shifting atmospheric response to global war

Scientists in the 1980s found that the enormous amounts of smoke from a nuclear war would cool the planet by blocking incoming sunlight, an outcome known as a “nuclear winter.” They also found that a nuclear war would destroy ozone because of chemical reactions involving nitrogen oxides produced from the fireball created by a nuclear weapon explosion.

Subsequent research, however, suggested that the smoke would also cause ozone loss by heating the stratosphere, which changes chemical reaction rates, and by reducing photochemistry (chemical reactions caused by sunlight).

In the new study, the authors explored how much the reduced photochemistry would affect ozone destruction, as well as the extent to which the smoke would protect the surface from UV radiation. They calculated, for the first time, the combined effects of nitrogen oxides, stratospheric heating, and reduced photochemistry on stratospheric ozone chemistry and surface UV resulting from a global nuclear war.

The research team combined four advanced NCAR-based computer models: the Community Earth System Model, which simulates global climate; the Whole Atmosphere Community Climate Model, which simulates higher regions of the atmosphere; the Tropospheric Ultraviolet and Visible Radiation Model, which calculates the light available for photolysis and the amount of UV radiation that reaches the surface; and the Community Aerosol and Radiation Model for Atmospheres, which provides an advanced treatment of smoke particles.

They used this modeling approach to study two scenarios. In one, a regional nuclear war between India and Pakistan produces 5 megatons of smoke. In the other, a global nuclear war between the United States and Russia produces 150 megatons of smoke.

The results highlighted the importance of using sophisticated modeling techniques to flesh out the complexities of the atmosphere. In the case of the global nuclear war, for example, the simulations showed that massive injection of smoke into the stratosphere would initially cool surface temperatures by blocking sunlight, alter precipitation patterns, shield the planet from incoming UV radiation, while also destroying the protective ozone layer. Within a few years, however, the smoke would begin to dissipate and far more UV radiation would reach the surface through the diminished ozone layer.

“Conditions would switch dramatically, and adaptations that may work at first won’t help as temperatures warm back up and UV radiation increases,” Bardeen said. “Just as the smoke is clearing up, you would get this blast of UV with completely different impacts on human health and agriculture.”

In contrast, a regional nuclear war that generated less smoke would result in a more straightforward pattern, with UV increasing right away while surface temperatures are decreasing and the ozone layer gradually recovering as the smoke dissipates.

While disappointing for those holding hope that oxytocin could benefit children with autism, the long-awaited finding provides clarity for a drug that has shown mixed outcomes in smaller, less robust studies.

“There was a great deal of hope this drug would be effective,” said the study’s principal investigator and lead author, Linmarie Sikich, M.D., associate consulting professor in the Department of Psychiatry & Behavioral Sciences at Duke University School of Medicine. “All of us on the study team were hugely disappointed, but oxytocin does not appear to change social function of people with autism.”

Oxytocin is typically used to induce labor, but because of its activity in the brain, it has been investigated as a treatment for autism. Evidence has been conflicting, with several smaller studies suggesting it improved social and cognitive function among some children with autism, while other studies showed no benefit.

Sikich and colleagues, including senior author Jeremy Veenstra-VanderWeele, M.D., of New York State Psychiatric Institute and Columbia University, designed the multi-site trial to provide the best evidence yet about whether oxytocin was a safe and effective treatment for children with Autism Spectrum Disorder.

The research team enrolled 290 children ages 3-17, stratified by age and the severity of their autism symptoms. The children were randomized in similar, equal-sized groups to receive oxytocin or a placebo via a daily nasal spray over 24 weeks.

The study aimed to see if the regimen of oxytocin would have a measurable impact on the children’s social abilities based on screenings and assessments at the start of the trial, midway through and at the end. Both researchers and the children’s parents provided assessments using standard analytic tools for autism.

While the oxytocin was well tolerated and had few side effects, it showed no significant benefit among the group of children who received it compared to those who received the placebo.

“Thousands of children with autism spectrum disorder were prescribed intranasal oxytocin before it was adequately tested,” Veenstra-VanderWeele said. “Thankfully, our data show that it is safe. Unfortunately, it is no better than placebo when used daily for months. These results indicate that clinicians and families should insist that there is strong evidence for the safety and benefit of new treatments before they are provided to patients in the clinic.”

Sikich said no further study is likely of oxytocin, given the negative findings: “Our consensus as investigators is that there is no evidence in this large study that is strong enough to justify more investigation of oxytocin as a treatment for autism spectrum disorders.”

In addition to Sikich and Veenstra-VanderWeele, study authors include Alexander Kolevzon, Bryan H. King, Christopher J. McDougle, Kevin B. Sanders, Soo-Jeong Kim, Marina Spanos, Tara Chandrasekhar, Pilar Trelles, Carol M. Rockhill, Michelle L. Palumbo, Allyson Witters Cundiff, Alicia Montgomery, Paige Siper, Mendy Minjarez, Lisa A. Nowinski, Sarah Marler, Lauren C. Shuffrey, Cheryl Alderman, Jordana Weissman, Brooke Zappone, Jennifer E. Mullett, Hope Crosson, Natalie Hong, Stephen K. Siecinski, Stephanie N. Giamberardino, Sheng Luo, Lilin She, Manjushri Bhapkar, Russell Dean and Abby Scheer.

The study received funding from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (U01HD073984) and the National Center for Advancing Translational Sciences (UL1TR002489).