The scientists were investigating the hippocampus, a brain area that plays a key role in memory in humans and mice. Specifically, they focused on the CA2 region, which is significant for social memory, the ability to remember other individuals, and the CA1 region, which is important for remembering places.

In this new study, the researchers for the first time reveal that CA1 and CA2 respectively encode the locations and individuals linked with a threatening experience. The results show that, beyond simply recognizing individuals, CA2 helps record more complex aspects of social memory: in this case, whether another individual is safe or risky. The scientists published their findings on October 15 in the journal Nature Neuroscience.

“It’s vital to all species that live in social communities, including mice and humans, to have social memories that can help one avoid future experiences with others that might prove harmful while keeping ourselves open to individuals who may be beneficial,” saidPegah Kassraian, PhD, a postdoctoral research fellow in the Siegelbaum lab and lead author of the new study. “Fearful memories are important for survival and help to keep us safe.”

To investigate where fearful social memories originate in the brain, Dr. Kassraian and her colleagues gave individual mice a choice. They could scamper to one place, meet another mouse that was unknown to them, and receive a mild foot shock (much like a static electricity zap people might get after walking on a carpet and touching a doorknob). Scurrying in the opposite direction to meet a different stranger was safe. Normally, the mice quickly learned to avoid the strangers and locations that were associated with the shocks, and these memories lasted for at least 24 hours.

To determine where in the hippocampus these memories were stored, the researchers genetically altered the mice to enable them to selectively suppress the CA1 or CA2 regions. Surprisingly, turning off each region had very different effects. When the scientists silenced CA1, the mice could no longer remember where they were zapped, but they could still remember which stranger was associated with the threat. When they silenced CA2, the mice remembered where they were shocked, but became indiscriminately afraid of both strangers they met.

These new findings reveal that CA2 helps mice remember whether past encounters with others were threatening or safe. The results also are consistent with prior research detailing how CA1 is home to place cells, which encode locations.

Previous research has implicated CA2 in various neuropsychiatric conditions such as schizophrenia and autism. The new study suggests that further investigating CA2 might help scientists better understand social anxiety, post-traumatic stress disorder and other conditions that can lead to social withdrawal.

“It’s possible that social withdrawal symptoms are related to an inability to discriminate between who is a threat and who is not,” said Dr. Siegelbaum, who is also a professor and chair of the department of neuroscience at Columbia’s Vagelos College of Physicians and Surgeons. “Targeting CA2 could be a useful way of diagnosing or treating disorders linked with a fear of others.”

The paper, “The hippocampal CA2 region discriminates social threat from social safety,” was published online in Nature Neuroscience on October 15, 2024.

The full list of authors includes Pegah Kassraian, Shivani K. Bigler, Diana M. Gilly, Neilesh Shrotri, Anastasia Barnett, Heon-Jin Lee, W. Scott Young, and Steven A. Siegelbaum.

The authors report no conflicts of interest.

The first human case of mpox was recorded in 1970 in the Democratic Republic of the Congo (DRC). Two types of the virus that causes mpox have been identified. Clade I is endemic in Central Africa and can cause severe illness. Clade II, endemic in West Africa, caused the global mpox outbreak that began in 2022 and tends to result in milder illness. People with compromised immune systems, children, and those who are pregnant are especially vulnerable to severe mpox regardless of the virus clade. A large proportion of people affected in the current Clade I outbreak in the DRC and other African countries are adolescents and children. The modified vaccinia Ankara-Bavarian Nordic (MVA-BN) vaccine is approved in several countries for the prevention of mpox and smallpox in adults, but insufficient data are available to support licensure for people younger than 18 years.

NIH’s National Institute of Allergy and Infectious Diseases (NIAID) is sponsoring a mid-stage study in the United States to evaluate the safety and immune response generated by two doses of MVA-BN in adolescents aged 12-17 years, comparing outcomes to those in adults aged 18-50 years. In a planned interim analysis, study investigators measured antibody levels two weeks after the second dose (study day 43) and monitored safety through 180 days after the second dose (study day 210). The analysis showed that the MVA-BN vaccine generated antibody levels in adolescents equivalent to those observed in adults at day 43 and found that the vaccine was well tolerated through study day 210. The overall frequency of adverse events was comparable between the study groups. Reports of dizziness were more common in adolescents than adults, but similar to the frequency of dizziness reported when other vaccines are administered in adolescents.

According to the study team, the interim data support the safety and quality of the immune response generated by the MVA-BN vaccine in adolescents, findings relevant to the United States and other areas where mpox cases have occurred. The authors underscored the need to evaluate the MVA-BN vaccine in younger children to extend the evidence base to all people affected by mpox.

NIH is grateful to the research sites and volunteers who participate in studies to improve the mpox response.

For more information about this study, please visit ClinicalTrials.gov and use the identifier NCT05512949.

Instead, it requires a simple mobile device.

Called MobilePoser, the new system leverages sensors already embedded within consumer mobile devices, including smartphones, smart watches and wireless earbuds. Using a combination of sensor data, machine learning and physics, MobilePoser accurately tracks a person’s full-body pose and global translation in space in real time.

“Running in real time on mobile devices, MobilePoser achieves state-of-the-art accuracy through advanced machine learning and physics-based optimization, unlocking new possibilities in gaming, fitness and indoor navigation without needing specialized equipment,” said Northwestern’s Karan Ahuja, who led the study. “This technology marks a significant leap toward mobile motion capture, making immersive experiences more accessible and opening doors for innovative applications across various industries.”

Ahuja’s team will unveil MobilePoser on Oct. 15, at the 2024 ACM Symposium on User Interface Software and Technology in Pittsburgh. “MobilePoser: Real-time full-body pose estimation and 3D human translation from IMUs in mobile consumer devices” will take place as a part of a session on “Poses as Input.”

An expert in human-computer interaction, Ahuja is the Lisa Wissner-Slivka and Benjamin Slivka Assistant Professor of Computer Science at Northwestern’s McCormick School of Engineering, where he directs the Sensing, Perception, Interactive Computing and Experience (SPICE) Lab.

Limitations of current systems

Most movie buffs are familiar with motion-capture techniques, which are often revealed in behind-the-scenes footage. To create CGI characters — like Gollum in “Lord of the Rings” or the Na’vi in “Avatar” — actors wear form-fitting suits covered in sensors, as they prowl around specialized rooms. A computer captures the sensor data and then displays the actor’s movements and subtle expressions.

“This is the gold standard of motion capture, but it costs upward of $100,000 to run that setup,” Ahuja said. “We wanted to develop an accessible, democratized version that basically anyone can use with equipment they already have.”

Other motion-sensing systems, like Microsoft Kinect, for example, rely on stationary cameras that view body movements. If a person is within the camera’s field of view, these systems work well. But they are impractical for mobile or on-the-go applications.

Predicting poses

To overcome these limitations, Ahuja’s team turned to inertial measurement units (IMUs), a system that uses a combination of sensors — accelerometers, gyroscopes and magnetometers — to measure a body’s movement and orientation. These sensors already reside within smartphones and other devices, but the fidelity is too low for accurate motion-capture applications. To enhance their performance, Ahuja’s team added a custom-built, multi-stage artificial intelligence (AI) algorithm, which they trained using a publicly available, large dataset of synthesized IMU measurements generated from high-quality motion capture data.

With the sensor data, MobilePoser gains information about acceleration and body orientation. Then, it feeds this data through AI algorithm, which estimates joint positions and joint rotations, walking speed and direction, and contact between the user’s feet and the ground.

Finally, MobilePoser uses a physics-based optimizer to refine the predicted movements to ensure they match real-life body movements. In real life, for example, joints cannot bend backward, and a head cannot rotate 360 degrees. The physics optimizer ensures that captured motions also cannot move in physically impossible ways.

The resulting system has a tracking error of just 8 to 10 centimeters. For comparison, the Microsoft Kinect has a tracking error of 4 to 5 centimeters, assuming the user stays within the camera’s field of view. With MobilePoser, the user has freedom to roam.

“The accuracy is better when a person is wearing more than one device, such as a smartwatch on their wrist plus a smartphone in their pocket,” Ahuja said. “But a key part of the system is that it’s adaptive. Even if you don’t have your watch one day and only have your phone, it can adapt to figure out your full-body pose.”

Potential use cases

While MobilePoser could give gamers more immersive experiences, the new app also presents new possibilities for health and fitness. It goes beyond simply counting steps to enable the user to view their full-body posture, so they can ensure their form is correct when exercising. The new app also could help physicians analyze patients’ mobility, activity level and gait. Ahuja also imagines the technology could be used for indoor navigation — a current weakness for GPS, which only works outdoors.

“Right now, physicians track patient mobility with a step counter,” Ahuja said. “That’s kind of sad, right? Our phones can calculate the temperature in Rome. They know more about the outside world than about our own bodies. We would like phones to become more than just intelligent step counters. A phone should be able to detect different activities, determine your poses and be a more proactive assistant.”

To encourage other researchers to build upon this work, Ahuja’s team has released its pre-trained models, data pre-processing scripts and model training code as open-source software. Ahuja also says the app will soon be available for iPhone, AirPods and Apple Watch.

The solar cycle is a natural cycle the Sun goes through as it transitions between low and high magnetic activity. Roughly every 11 years, at the height of the solar cycle, the Sun’s magnetic poles flip — on Earth, that’d be like the North and South poles swapping places every decade — and the Sun transitions from being calm to an active and stormy state.

NASA and NOAA track sunspots to determine and predict the progress of the solar cycle — and ultimately, solar activity. Sunspots are cooler regions on the Sun caused by a concentration of magnetic field lines. Sunspots are the visible component of active regions, areas of intense and complex magnetic fields on the Sun that are the source of solar eruptions.

“During solar maximum, the number of sunspots, and therefore, the amount of solar activity, increases,” said Jamie Favors, director, Space Weather Program at NASA Headquarters in Washington. “This increase in activity provides an exciting opportunity to learn about our closest star — but also causes real effects at Earth and throughout our solar system.”

Solar activity strongly influences conditions in space known as space weather. This can affect satellites and astronauts in space, as well as communications and navigation systems — such as radio and GPS — and power grids on Earth. When the Sun is most active, space weather events become more frequent. Solar activity has led to increased aurora visibility and impacts on satellites and infrastructure in recent months.

During May 2024, a barrage of large solar flares and coronal mass ejections (CMEs) launched clouds of charged particles and magnetic fields toward Earth, creating the strongest geomagnetic storm at Earth in two decades — and possibly among the strongest displays of auroras on record in the past 500 years.

“This announcement doesn’t mean that this is the peak of solar activity we’ll see this solar cycle,” said Elsayed Talaat, director of space weather operations at NOAA. “While the Sun has reached the solar maximum period, the month that solar activity peaks on the Sun will not be identified for months or years.”

Scientists will not be able to determine the exact peak of this solar maximum period for many months because it’s only identifiable after they’ve tracked a consistent decline in solar activity after that peak. However, scientists have identified that the last two years on the Sun have been part of this active phase of the solar cycle, due to the consistently high number of sunspots during this period. Scientists anticipate that the maximum phase will last another year or so before the Sun enters the declining phase, which leads back to solar minimum. Since 1989, the Solar Cycle Prediction Panel — an international panel of experts sponsored by NASA and NOAA — has worked together to make their prediction for the next solar cycle.

Solar cycles have been tracked by astronomers since Galileo first observed sunspots in the 1600s. Each solar cycle is different — some cycles peak for larger and shorter amounts of time, and others have smaller peaks that last longer.

“Solar Cycle 25 sunspot activity has slightly exceeded expectations,” said Lisa Upton, co-chair of the Solar Cycle Prediction Panel and lead scientist at Southwest Research Institute in San Antonio, Texas. “However, despite seeing a few large storms, they aren’t larger than what we might expect during the maximum phase of the cycle.”

The most powerful flare of the solar cycle so far was an X9.0 on Oct. 3 (X-class denotes the most intense flares, while the number provides more information about its strength).

NOAA anticipates additional solar and geomagnetic storms during the current solar maximum period, leading to opportunities to spot auroras over the next several months, as well as potential technology impacts. Additionally, though less frequent, scientists often see fairly significant storms during the declining phase of the solar cycle.

NASA and NOAA are preparing for the future of space weather research and prediction. In December 2024, NASA’s Parker Solar Probe mission will make its closest-ever approach to the Sun, beating its own record of closest human-made object to the Sun. This will be the first of three planned approaches for Parker at this distance, helping researchers to understand space weather right at the source.

NASA is launching several missions over the next year that will help us better understand space weather and its impacts across the solar system.

Space weather predictions are critical for supporting the spacecraft and astronauts of NASA’s Artemis campaign. Surveying this space environment is a vital part of understanding and mitigating astronaut exposure to space radiation.

NASA works as a research arm of the nation’s space weather effort. To see how space weather can affect Earth, please visit NOAA’s Space Weather Prediction Center, the U.S. government’s official source for space weather forecasts, watches, warnings, and alerts:

https://www.spaceweather.gov/