Tuesday, May 05, 2026

Climate change increases spillover risk of rodent-borne arenaviruses



As rodents and temperatures shift, arenaviruses pose future threat to South American communities





University of California - Davis

Drylands vesper mouse 

image: 

A drylands vesper mouse in Argentina is among the rodent species studied in a UC Davis study that found rodent-borne viruses in South America are expected to increase and expand as temperatures rise and rodent habitats shift with climate change.

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Credit: ignacio_hernandez, ArgentiNat





Climate change is likely to drive rodent-borne arenaviruses into parts of South America that have never faced these diseases, putting new communities of people at risk, finds a study from the University of California, Davis. 

For the study, published in the journal npj Viruses, scientists incorporated climate projections, shifting rodent populations and the risks of human infection into a model to offer an early risk projection for arenaviruses and other diseases in the next 20 to 40 years.

“As climate change accelerates, our study shows how the outbreak risk of dangerous New World arenaviruses could ride on shifting rodent populations to reach millions more people across South America,” said lead author Pranav S. Kulkarni, a postdoctoral scholar in the UC Davis Weill School of Veterinary Medicine and its Department of Population Health and Reproduction. 

South American New World arenaviruses

Arenaviruses can cause severe hemorrhagic fevers with high hospitalization rates and fatality rates ranging from about 5% to 30%. South American New World arenaviruses include Guanarito virus in Venezuela and Colombia, Machupo virus in Bolivia and Paraguay, and Junin virus in Argentina. Despite having caused multiple outbreaks in humans, they are relatively understudied compared to Old World arenaviruses, such as Lassa fever in Africa.

With funding from Wellcome Trust, the researchers built an interactive, open-source platform called AtlasArena, to understand how climate change is reshaping the risk of zoonotic spillover for arenaviruses and other hard-to-track viruses. They integrated climate projections, habitat suitability for six rat and mouse species linked to the viruses, human population density, and transmission risk into machine learning models. This approach allowed the team to identify complex relationships among climate, land use, rodent ecology and human exposure that traditional models may miss.

Where arenaviruses may next emerge

“Our study connects the dots between changing climatic conditions and land use, shifting rodent populations and human infection risk, making it possible to see where the next generation of zoonotic arenaviral outbreaks could emerge,” said senior author Pranav Pandit, an assistant professor of veterinary epidemiology at the UC Davis Weill School of Veterinary Medicine. 

For example, the models project that:

  • Guanarito virus, which is found in central Venezuela, is expected to spread to parts of Colombia, the borders of Suriname and northern parts of Brazil. 
  • Machupo virus is expected to move from the plains and flatlands of Bolivia to the Andes foothills and mountain regions. 
  • Junin virus is expected to move from the grassland regions to other parts of Argentina, reducing risk in some regions while expanding risk to other areas. 
  • In all cases, populations with little or no prior exposure would be encountering these viruses for the first time, potentially increasing their vulnerability to infection and severe disease.

The risk of spillover is primarily driven by changes in temperature, precipitation and land use, such as expanding agricultural and urban areas within rodent reservoir habitats.

Coordinated, transboundary public health needs

The authors say the results underscore an urgent need for coordinated climate-adaptive public health policies and transboundary collaboration among countries at risk. 

“The first thing a study like this can inform is where we expect the risk to increase,” Kulkarni said. “Then we can look at why it is happening in more detail, identify ways to reduce the risk, and start planning for the long term and ways to reduce the spread of disease.”

The authors note their work with the AtlasArena platform is ongoing, freely available, and that its insights can be adapted to study other poorly monitored, climate-sensitive diseases spread by animals. 

The study’s additional coauthors include Nuri Flores-Perez of UC Davis and currently San Diego Zoo, and Andie Jian, Brian Bird, Christine Johnson and Marcela Uhart from the UC Davis Weill School of Veterinary Medicine.

 

Sharks may help improve climate forecasts, study finds



Research demonstrates how animal-borne sensors can work in tandem with traditional tools to improve ocean predictions




University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science

Sharks may help improve climate forecasts, study finds 

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Neil Hammerschlag, Ph.D. and Laura McDonnell, Ph.D. attach a satellite tag to a blue shark that transmitted location, temperature, and depth data. 

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Credit: Nola Schoder, MPS






MIAMI— A new study published in the journal npj Climate and Atmospheric Science, shows that electronically tagged sharks can serve as mobile sensors, collecting ocean climate data in regions that are difficult to observe using conventional methods.

The study is led by Laura H. McDonnell, Ph.D., who conducted the research as a doctoral student at the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science and the Abess Center for Ecosystem Science and Policy. Its findings demonstrate that temperature and depth data gathered by tagged sharks can enhance ocean forecast accuracy in dynamic regions of the Northwest Atlantic.

By incorporating shark-collected data into a seasonal climate model, McDonnell and her team found that forecast errors at the ocean surface decreased substantially in certain regions, with improvements reaching as much as 40 percent in specific cases.

This is the first study to experimentally integrate animal-borne sensor data into a seasonal climate model and quantify its impact on forecast performance, suggesting potential for future operational use.

“Sharks are already moving through parts of the ocean that are challenging for us to observe,” said McDonnell, now a postdoctoral investigator at the Woods Hole Oceanographic Institution (WHOI). “This research shows that data they collect can help fill important gaps and, when used carefully, can improve how we predict ocean conditions.”

Interdisciplinary collaboration fuels innovation

The study originated from an interdisciplinary collaboration between former Rosenstiel School shark scientist Neil Hammerschlag, Ph.D. and atmospheric scientist Ben Kirtman, Ph.D., now dean of the Rosenstiel School. In 2018, they recognized that the data from shark-tagging studies used by Hammerschlag’s lab to study shark ecology could also benefit climate modeling.

Satellite tags attached to sharks record depth and temperature as they travel through the ocean, collecting and transmitting this data in near real time. While these tags have long helped scientists track shark movements, the collaboration opened a new application and a chance to create a novel proof of concept: using the same data to improve climate forecasts.

“Marine predators like sharks naturally seek out dynamic ocean features such as fronts and eddies,” said Kirtman. “These are areas where models often lack sufficient observations.”

Supported by a grant from Cisco Systems, the team conducted fieldwork and tested the concept.

Testing sharks as ocean observers

McDonnell and Hammerschlag tagged 18 blue sharks (Prionace glauca) and one shortfin mako shark (Isurus oxyrinchus) in the Northwest Atlantic. The sharks transmitted more than 8,200 temperature-depth profiles across a wide range of locations and depths—down to nearly 2,000 meters. WHOI oceanographer and study co-author Camrin Braun, Ph.D., helped facilitate this field work off Cape Cod, MA by connecting McDonnell and Hammerschlag with a local fisherman and co-led the forecast data analysis.

“Key to this study was repurposing a more advanced tag capable of transmitting location data along with temperature and depth information,” said Hammerschlag, co-author of the study and executive director of the Shark Research Foundation. “This allowed us to link subsurface ocean conditions directly to specific locations with known accuracy.”

Kirtman integrated a subset of these data into the Community Climate System Model, a coupled ocean–atmosphere–ice–land model used in seasonal forecasting applications that forms part of the National Oceanic and Atmospheric Administration’s operational North American Multi-Model Ensemble (NMME) system, of which Kirtman is the lead scientist.

The team compared the actual resulting climate conditions with the forecasted predictions from traditional models as well as the ones that integrated the shark collected data.

The results showed measurable improvements in forecast performance, particularly in dynamic coastal and shelf regions that are important for marine ecosystems and fisheries.

The researchers emphasize that animal-borne sensors are not a replacement for traditional observing systems but a complementary tool.

“Tagged sharks won’t replace conventional observing systems,” added McDonnell. “What the preliminary results do show is that tagged marine predators can provide complementary in-situ observations at the surface and at depth.”

Why it matters

Accurate ocean forecasts are critical for fisheries management, marine operations, and understanding how climate variability affects coastal communities. However, forecasts are often least reliable in regions where conditions change rapidly and observational data are lacking.

Animal-borne sensors could enhance predictions that support decision-making across multiple sectors, ranging from seafood supply chains to climate adaptation planning.

“Marine animals are already being tracked to understand their behavior in relation to environmental conditions, but this study reveals how these data can also be leveraged for forecasting and climate applications,” said Hammerschlag.

“For fisheries and coastal communities, small improvements in ocean forecasts can make a big difference,” said Braun. “Reducing uncertainty helps people plan, whether that’s where to fish, how to manage resources, or how to respond to changing conditions.”

The study, titled Improved seasonal climate forecasting using shark-borne sensor data in a dynamic ocean,” was published on April 28, 2026 in the journal npj Climate and Atmospheric Science.

Funding for the research was provided by Cisco Systems (AWP-014524) and the University of Miami Abess Center.

The authors and their affiliations for this study are as follows: Laura H. McDonnell & Neil Hammerschlag, Rosenstiel School of Marine, Atmospheric and Earth Science, and the Leonard and Jayne Abess Center for Ecosystem Science and Policy at the University of Miami. Ben P. Kirtman, Rosenstiel School and the Cooperative Institute for Marine and Atmospheric Studies, and the Frost Institute for Data Science and Computing, all at the University of Miami, and Camrin D. Braun, Woods Hole Oceanographic Institution.

About the University of Miami and Rosenstiel School of Marine, Atmospheric and Earth Science

The University of Miami is a private research university and academic health system with a distinct geographic capacity to connect institutions, individuals, and ideas across the hemisphere and around the world. The University’s vibrant academic community comprises 12 schools and colleges serving more than 19,000 undergraduate and graduate students in more than 180 majors and programs. Located within one of the most dynamic and multicultural cities in the world, the University is building new bridges across geographic, cultural, and intellectual borders, bringing a passion for scholarly excellence, a spirit of innovation, and a commitment to tackling the challenges facing our world. The University of Miami is a member of the prestigious Association of American Universities (AAU).

 Founded in 1943, the Rosenstiel School of Marine, Atmospheric, and Earth Science is one of the world’s premier research institutions in the continental United States. The School’s basic and applied research programs seek to improve understanding and prediction of Earth’s geological, oceanic, and atmospheric systems by focusing on four key pillars:

*Saving lives through better forecasting of extreme weather and seismic events. 

*Feeding the world by developing sustainable wild fisheries and aquaculture programs. 

*Unlocking ocean secrets through research on climate, weather, energy and medicine. 

*Preserving marine species, including endangered sharks and other fish, as well as protecting and restoring threatened coral reefs. www.earth.miami.edu

Sharks may help improve climate forecasts, study finds [VIDEO] 


Sharks may help improve climate forecasts, study finds 

Example shark-derived temperature–depth profiles across four regions, with the distribution of all transmitted profile locations (October 2021–April 2022). Top panels compare tag-derived profiles within a 1° × 1° grid cell on a given day to the concurrent control (CFSR) profile (black), with shark tag data showing minimum (blue) and maximum (red) temperatures. Summary statistics for each grid cell are provided in-panel. The bottom map shows all profile locations and maximum depths (N = 8,242), with colored diamonds marking example profiles, orange lines indicating the Gulf Stream, and the black line marking 200 m depth.

Credit

Laura McDonnell, Ph.D.

 

Cannabis microdosing more common than psychedelics among US adults, national survey finds



Across substances, people reporting poorer mental health were more likely to report microdosing




University of California - San Diego






Key takeaways:

  • Cannabis is the most commonly microdosed substance in the U.S., with about 9.4% of adults — roughly 24 million people — reporting lifetime use. More people reported microdosing for recreational reasons than for medical reasons.

  • Cannabis microdosing was nearly twice as common as psilocybin, LSD or MDMA, challenging the perception that microdosing is mainly a psychedelic practice.

  • Microdosing was more common among people reporting poorer mental health.

Researchers from University of California San Diego have found that microdosing — taking very small amounts of psychoactive substances — is more common among U.S. adults than previously recognized, with cannabis leading by a wide margin. The study, published May 4, 2026 in the American Journal of Preventive Medicine, estimates that millions of Americans have microdosed substances such as cannabis, psilocybin, LSD (“acid”) and MDMA (“ecstasy”).

“Microdosing is often discussed in the context of psychedelics like psilocybin or LSD, but what surprised us most was that cannabis microdosing was almost twice as common,” said Kevin Yang, MD, resident physician in the Department of Psychiatry at UC San Diego School of Medicine and first author of the study. “That suggests conversations about microdosing may be overlooking a large group of people who are using small amounts of cannabis in similar ways.”

“Most proponents of microdosing recommend use under specific protocols that involve taking low doses of LSD or psilocybin for specific health applications,” said Eric Leas, PhD, MPH, assistant professor at the UC San Diego Herbert Wertheim School of Public Health and Human Longevity Science and senior author of the study. “That’s not what we found. Most people are microdosing for recreational purposes. That suggests that many people could think about the concept of ‘microdosing’ more as a way of lowering dosage. They may just want to take less, so they don’t want to get as high.”

Microdosing typically involves consuming about one-fifth to one-twentieth of a typical recreational dose, with the goal of avoiding strong psychoactive effects while potentially experiencing subtler benefits such as improved mood, reduced anxiety or enhanced creativity.

To better understand how common the practice is, researchers analyzed data from a nationally representative survey of 1,525 U.S. adults conducted in late 2023 through the Ipsos KnowledgePanel, which uses probability-based sampling to reflect the U.S. population. Participants were asked whether they had ever intentionally microdosed cannabis, psilocybin mushrooms, LSD or MDMA.

The results suggest that cannabis is the most commonly microdosed substance. About 9.4% of U.S. adults — an estimated 24.1 million people — reported microdosing cannabis at least once in their lifetime. In comparison, 5.3% reported microdosing psilocybin, 4.8% LSD and 2.2% MDMA.

Ongoing microdosing was less common but still measurable: roughly 3.3% of adults reported currently microdosing cannabis, compared with about 1.0% for psilocybin, 0.6% for LSD and 0.3% for MDMA.

The study also found that the reasons for microdosing differed by substance. Cannabis microdosing was most often reported for medical reasons, including managing anxiety, depression or chronic pain. In contrast, psilocybin, LSD and MDMA were more frequently microdosed for recreational purposes, such as achieving a milder psychoactive experience.

Researchers also observed patterns tied to mental health and policy environments. Across substances, people reporting poorer mental health were more likely to report microdosing. For example, cannabis microdosing was reported by about 21% of adults who rated their mental health as “poor,” compared with about 8% among those reporting “excellent” mental health.

In addition, microdosing of psychedelics such as psilocybin and LSD was more common in places where laws were more permissive — meaning, jurisdictions that have decriminalized psychedelic possession. The findings suggest that changes in drug policy may influence both access to these substances and people’s willingness to report using them.

Despite growing public interest, the researchers emphasize that scientific evidence on the health effects of microdosing remains limited. Few placebo-controlled clinical trials have been conducted and existing studies have produced mixed findings about potential benefits. Additional risks stem from the unregulated nature of many of these substances, including the possibility of adulterated products or dosing errors — especially since most people who microdose do not test the substances they use.

“There’s a lot of anecdotal enthusiasm around microdosing, especially for mental health,” said Leas. “But we still need rigorous studies to determine whether these perceived benefits are real, who might benefit and what the potential risks could be.”

The authors note that because the study was cross-sectional, it cannot determine whether microdosing influences mental health outcomes or whether people experiencing mental health challenges are more likely to try microdosing. Future research, including longitudinal studies and clinical trials, will be needed to clarify those relationships.

As cannabis legalization and psychedelic policy reforms continue to evolve across the United States, the researchers say monitoring patterns of microdosing will become increasingly important for public health.

“Microdosing appears to be a growing behavior that cuts across different substances and motivations,” Leas said. “Understanding how and why people are using these small doses is essential if we want to develop evidence-based policies and guidance for clinicians and the public.”

Link to full study: https://doi.org/10.1016/j.amepre.2026.108381

Additional co-authors on the study include: Joseph Friedman, MD, and Siyuan Ping from UC San Diego. Nora Satybaldiyeva, PhD, and Wayne Kepner, PhD, from Stanford University.

The study was funded, in part, by the U.S. National Institute on Drug Abuse (grant #K01DA054303, PI: Leas). Satybaldiyeva acknowledges salary support from the National Heart, Lung, and Blood Institute (grant #5T32HL161270-03). Kepner acknowledges salary support from the National Institute on Drug Abuse of the National Institutes of Health (#T32DA035165), and the William and Katharine Duhamel Addiction Medicine Fund.

Authors declare no competing interests.

 

How do rats determine whether to approach or avoid distressed peers?



Researchers identified a pathway in the rat brain that plays a role in evaluating social signals and making decisions to approach stressed pups or avoid stressed adult peers.




Society for Neuroscience






In a new JNeurosci paper, a Boston College research team led by John Christianson explored how a pathway between two areas of the brain—the insular cortex and prefrontal cortex—supports social decisions in male rats. Why did the researchers choose to assess the insular cortex and prefrontal cortex of rats? Says Christianson, “For rodents and humans alike, the insular cortex is a brain region where contextual information about the environment and the self are bound together. The insular cortex sends this information to the prefrontal cortex, which is one of the final brain areas involved in making decisions. Because our internal states can shape our decisions, we hypothesized that connections between the insula and prefrontal cortex would be necessary for social responses to others in distress.” 

In a task where rats were exposed to either stressed pups or adult peers, rats tended to approach juveniles while avoiding adults. The ability to make these social decisions required both the prefrontal cortex and insula, as well as intact signaling between these areas. The researchers theorize this signaling may mean that rats find the presence of a distressed pup a more urgent social situation requiring less evaluative effort and quicker action than a situation involving a distressed adult peer, whose reason for being distressed may be more unclear to the rats. 

Addressing remaining unknowns, says Christianson, “We know that when you take the pathway away, it affects behavior. But we can’t tell exactly what information is relayed from the insula to the prefrontal cortex. We plan to record neural activity in these regions seeking to decode which aspects of social encounters are processed in this circuit. Is it stress? Age? Threat? Or all of the above?” This work may ultimately help with developing treatment strategies for psychiatric conditions characterized by social anxiety or trauma, according to the authors. 

### 

Please contact media@sfn.org for full-text PDF. 

About JNeurosci 

JNeurosci was launched in 1981 as a means to communicate the findings of the highest quality neuroscience research to the growing field. Today, the journal remains committed to publishing cutting-edge neuroscience that will have an immediate and lasting scientific impact, while responding to authors' changing publishing needs, representing breadth of the field and diversity in authorship. 

About The Society for Neuroscience 

The Society for Neuroscience is the world's largest organization of scientists and physicians devoted to understanding the brain and nervous system. The nonprofit organization, founded in 1969, now has nearly 35,000 members in more than 95 countries. 

 

Can dopamine bend time to shape memory?



The brain may use dopamine to expand time between distinct events, enabling us to remember unique episodes.




University of California - Los Angeles






Key takeaways

  • Why do we often recall events as lasting longer or shorter than they did? New research by UCLA psychologists shows that dopamine signaling at event beginnings may stretch time in our memory. 

  • A key dopamine-producing area of the brain — the ventral tegmental area — was activated when volunteers participating in an MRI scan detected the start of a new event. When this dopamine hub activated more strongly, people later reported more time had passed.

  • The finding suggests that dopamine plays a role in breaking lived experience into meaningful segments that can be stored as memories.

Ever heard of getting a “dopamine hit” from something you enjoy? These exciting moments also appear to influence memory, although perhaps not in the way you’d expect.

New research by UCLA psychologists suggests your brain may use dopamine to distort and expand time between distinct events, separating the flow of experience into pieces that can be flexibly reconstructed in the future.

The study, published in Nature Communications, found that a key dopamine-producing area of the brain — the ventral tegmental area — was activated when volunteers participating in an MRI scan detected the start of a new event. Importantly, when this dopamine hub was strongly activated, people reported more time had passed. The researchers also found that when people blinked more during a new event — an action thought to be related to dopamine signaling — their memory for time once again expanded. 

“Dopamine is often talked about in the media as a chemical that makes things feel rewarding. People say we get a burst of dopamine when we eat food that we like, or when we scroll on social media, for example,” said first author and UCLA doctoral student Erin Morrow. “But the dopamine system in our brain also responds strongly to novelty and change. We found that activation of the dopamine system at the beginning of a new event is likely one of the ways that our brain segments experiences into memorable episodes.

How do we form durable memories from the steady flow of life’s experiences?

When we summon a memory, we may recall events as having unfolded very quickly or having dragged on at unbearable slowness. But that’s not actually how time elapsed in the moment. It’s somewhat of a puzzle, then, how our brain adds or subtracts time from the original flow of our experiences. This question is important because how our brain constructs new memories is related to how we experience and represent time.

UCLA psychology professor David Clewett studies how the brain marks event boundaries, which are transitions between different noteworthy contexts, to segment experience into a more organized format that can be retrieved later as memory.

“Time is often treated as a physical dimension,” said Clewett. “But in psychology, time isn’t fixed. It’s something the brain constructs and is shaped by experience. As my colleague, professor Dean Buonomano puts it, our sense of time is evolution’s way of allowing us to understand change. Our findings suggest that this process also shapes memory. I think of it as inserting small wedges into an otherwise continuous stream, helping neighboring events stand apart.”

“The purpose of memory is not always to reconstruct the past completely accurately,” said Morrow. “It helps us remember past experiences in the most useful way possible so that we can change our future behavior.”

The dopamine system is engaged when new events happen

Researchers asked 32 volunteers to look at pictures of neutral objects while inside an MRI scanner. In between each object, tones were played in either the right or left ear. The same tone was repeated in the same ear across eight consecutive items to create a sense of a coherent event. The tone then switched to the other ear and changed pitch to create an “event boundary,” a meaningful change that signaled the current event had ended and the next had begun.

This repeat-switch pattern continued throughout the remainder of the sequence, creating the perception of four different auditory events. Functional magnetic resonance imaging (fMRI) revealed strong activation of the ventral tegmental area (VTA) when changes occurred, suggesting that dopamine signaling was taking place. Stronger VTA responses were also associated with increased blinking, consistent with other evidence linking dopamine signaling to blinking.

Participants were then presented with pairs of images from the earlier sequence and asked how far apart in time they appeared. However, the “secret” was that the images were all actually the same distance apart in time. Strikingly, participants remembered items that spanned tone switches as occurring farther apart. This finding suggested that the tone switch — and the VTA response accompanying it — had helped separate the objects into different memories. If people blinked more often across this window, they also remembered the items as occurring further apart.

 “We think the time dilation effect we found is useful, even though it’s not accurate, because it may help push those experiences farther apart in memory,” said Morrow.

Morrow said that the literature on the relationship between blinking and dopamine is mixed. She pointed out that many studies focus on blinking at rest or in people living with disorders related to atypical dopamine levels. In contrast, the current study took the novel approach of looking at dopamine and blinking while people without diagnosed psychiatric disorders were actively perceiving events.

How does change mark time in human memory?

This study represents an important step toward understanding how dopamine shapes memory. However, there are a few important limitations. These brain scans can’t directly measure dopamine release, nor whether it causes time dilation directly. More research is needed to see whether these laboratory-based effects also apply to more complex, real-world experiences.

Even so, these findings could begin to shed light on why time feels so flexible and why it can differ so drastically across people and situations. Alongside novel or rewarding experiences, dopamine is also pumped across the brain during stress. This may help explain our strange memories of time during the COVID-19 pandemic. For many people, lockdown felt slow in the moment, yet occupies surprisingly little space in memory. Long stretches of Zoom meetings or online learning at home offered few contextual changes, leading those periods to later be indistinguishable and compressed. By contrast, the early periods of the pandemic – marked by stress and upheaval – often feel expanded in memory. Together, these examples demonstrate that when experiences are more eventful, the brain has more information to work with. 

“Perhaps most importantly, our findings suggest that we don’t simply move through time,” says Clewett. “It is something we help create. By embracing change and variety, we expand our memories and, in that sense, expand our lives.”

The research was funded by the National Institutes of Health.