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A ‘Memory Switchboard’ in the Hippocampus May Help Explain How the Brain Learns Without Overwriting Old Memories


Scientists have often wondered how the brain can take in new experiences without erasing stored memories. However, a new study in Nature now identifies a circuit-level mechanism that may help answer this question—and it may also offer clues for improving artificial intelligence.

Researchers at NYU Langone Health recorded the activity of hundreds of neurons simultaneously across several brain regions in mice. By tracking how signals move from the hippocampus to the neocortex, where long-term memories are kept, they found that a subset of hippocampal neurons appears to participate in routing information between regions in distinct patterns. These cells participate in both incoming and outgoing signaling, but do so using distinct patterns of activity.

Separate Channels Through the Same Cells

The study focused on a series of interconnected brain regions: CA3, which processes rapidly changing information; CA1, which serves as a central hub; and the retrosplenial cortex, which is important for navigation and spatial memory. About one in four CA1 neurons receives most of the signals from CA3. When these same neurons send signals to the retrosplenial cortex, they fire in a different pattern, creating a separate outgoing channel using the same cells.

Rather than using new neurons, the brain separates these channels by changing how the same neurons fire together. The researchers suggest this arrangement may help reduce interference between new learning and more stable cortical memories.

“Our findings help explain how memory can be both moldable and enduring,” said co-lead author Joaquín Gonzalez, PhD, a postdoctoral fellow in the Department of Psychiatry at NYU Grossman School of Medicine. “By changing how the same cells fire together instead of turning on new cells, the brain can keep information organized and protect older memories.”

What Happens During Sleep

The CA1 neurons involved in learning during the day also stay active at night. The researchers found that these cells remain busy during sleep events called sharp-wave ripples, which are bursts of activity the hippocampus uses to replay and strengthen memories from the day.

Since overlapping neurons are recruited during both waking activity and sleep replay, the same circuit elements appear to participate in both learning and consolidation. This theoretically allows the brain to use a single system for both learning and storing memories, without the two processes interfering with each other.

“Our study shows how learning and memory consolidation can coexist in the same network,” said co-lead author Mihály Vöröslakos, MD, PhD. “Our discovery was made possible because for the first time, we were able to record hundreds of individual neurons across all the key regions simultaneously in animals that were moving around naturally.”

Implications for Disease and AI

The system identified in this research may help explain how memory disorders begin. In Alzheimer’s disease, for example, the hippocampal circuits examined here are some of the earliest to deteriorate. These networks are essential for sorting and organizing new experiences.

“Our discovery of a ‘memory switchboard’ deep in the hippocampus may provide clues as to how memory circuits fail in Alzheimer’s disease,” said co-senior author Zhe S. Chen, PhD, a professor in the Departments of Psychiatry and Neuroscience at NYU Grossman School of Medicine.

Artificial intelligence systems have a hard time holding onto what they’ve already learned when faced with new tasks, a problem researchers call catastrophic forgetting. The human brain appears able to update memories without catastrophic forgetting by altering the use of existing neural circuits. By studying how our brains pull this off, scientists hope to design AI that can keep learning new things without forgetting the old.

“By showing how the mammalian brain can safeguard memories during learning, our research may offer a biological blueprint for designing next-generation AI technology that can update itself continuously without overwriting what it has already acquired,” said co-senior author György Buzsáki, MD, PhD, the Biggs Professor of Neuroscience at NYU Grossman School of Medicine.

The researchers plan to investigate whether similar switchboard-like channels exist in other memory circuits. The authors caution that their findings in mice under controlled conditions do not yet allow conclusions about the human brain.

Austin Burgess is a writer and researcher with a background in sales, marketing, and data analytics. He holds an MBA, a Bachelor of Science in Business Administration, and a data analytics certification. His work focuses on breaking scientific developments, with an emphasis on emerging biology, cognitive neuroscience, and archaeological discoveries.

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World Cup Fever in Guadalajara

April 13, 1986
April 27, 2026
: Images of Guadalajara in 1986 (left) and 2026 (right) shows the city expanding westward into an area that had been mostly farmland. Guadalajara Stadium appears as a small circular feature on the left side of the 2026 image.
A pair of Landsat images shows 40 years of westward urban expansion from Guadalajara, Mexico. The Thematic Mapper on Landsat 5 captured the left image in 1986; the Operational Land Imager on Landsat 8 captured the right image in 2026.
Images of Guadalajara in 1986 (left) and 2026 (right) shows the city expanding westward into an area that had been mostly farmland. Guadalajara Stadium appears as a small circular feature on the left side of the 2026 image.
A pair of Landsat images shows 40 years of westward urban expansion from Guadalajara, Mexico. The Thematic Mapper on Landsat 5 captured the left image in 1986; the Operational Land Imager on Landsat 8 captured the right image in 2026.
NASA Earth Observatory / Lauren Dauphin
: Images of Guadalajara in 1986 (left) and 2026 (right) shows the city expanding westward into an area that had been mostly farmland. Guadalajara Stadium appears as a small circular feature on the left side of the 2026 image.
A pair of Landsat images shows 40 years of westward urban expansion from Guadalajara, Mexico. The Thematic Mapper on Landsat 5 captured the left image in 1986; the Operational Land Imager on Landsat 8 captured the right image in 2026.
Images of Guadalajara in 1986 (left) and 2026 (right) shows the city expanding westward into an area that had been mostly farmland. Guadalajara Stadium appears as a small circular feature on the left side of the 2026 image.
A pair of Landsat images shows 40 years of westward urban expansion from Guadalajara, Mexico. The Thematic Mapper on Landsat 5 captured the left image in 1986; the Operational Land Imager on Landsat 8 captured the right image in 2026.
NASA Earth Observatory / Lauren Dauphin
April 13, 1986
April 27, 2026

April 13, 1986 – April 27, 2026

A pair of Landsat images shows 40 years of westward urban expansion from Guadalajara, Mexico. The TM (Thematic Mapper) on Landsat 5 captured the left image in 1986; the OLI (Operational Land Imager) on Landsat 8 captured the right image in 2026.

Guadalajara, Mexico, was quite a different place when it last hosted World Cup games 40 years ago. The city welcomed matches in June 1986 and did so again in 2026, when South Korea faced Czechia at Guadalajara Stadium in the opening round of the 2026 FIFA World Cup.

In 1986, Guadalajara Stadium had not yet been built in Zapopan, the fast-growing municipality just northwest of Guadalajara. Many of that year’s World Cup matches were held instead at Jalisco Stadium in northeastern Guadalajara. It was in that stadium that France defeated Brazil in a penalty shootout in the 1986 quarterfinals, in what is widely regarded as one of the most memorable World Cup games of all time.

As seen in the Landsat images above, the land where Guadalajara Stadium (also called Estadio Akron) now sits was farmland in 1986. The new stadium, built in 2010 to host Mexico’s Club Deportivo Guadalajara, or Chivas, lies near the Sierra la Primavera volcanic complex, a rugged landscape full of lava flows, volcanic domes, steam vents, and hot springs. The architects who designed the stadium took inspiration from the nearby volcanic terrain, creating a structure that rises from a grassy earthen berm meant to resemble the flanks of a volcano, topped with a white roof reminiscent of a volcanic cloud.   

About 95,000 years ago, the volcanic system underneath Sierra la Primavera produced a massive eruption that caused a caldera 11 kilometers (7 miles) in diameter to slump downward. Water filled the depression for tens of thousands of years, but tectonic uplift and the accumulation of sediment eventually led to the demise of the lake. Erosion wore away the softer surrounding rock over time, leaving harder, erosion-resistant volcanic rocks within the circular feature that now stand high above the surrounding terrain.

Starting about 60,000 years ago, several lava domes erupted along the southern edge of the caldera. The youngest of them, Cerro del Colli, formed about 30,000 years ago, leaving the dome-shaped feature just south of the stadium and contributing to a broader landscape dotted with other volcanic domes and cinder cones.

Today, much of the original caldera has been preserved as a forested area known as La Primavera Biosphere Reserve, even as development has partially encircled it during the past 40 years. The population of the Guadalajara metro area has grown from about 2.7 million in 1986 to more than 5.5 million now, with particularly rapid growth in Zapopan, a burgeoning tech hub sometimes billed as “Mexico’s Silicon Valley.” A prominent development visible in Landsat images is Guadalajara Technology Park, one of several new industrial parks in Zapopan. New greenhouses have also come to the area en masse, including south of the reserve, where they are mostly used to grow fruits and vegetables.

World Cup fever runs particularly high in Guadalajara, which is hosting World Cup matches for the third time. During Brazil’s legendary title run in 1970, when Pelé led the team, Jalisco Stadium was the venue for Brazil’s first-round, quarterfinal, and semifinal matches. To commemorate him, the city in May 2026 erected a 9.5-meter (31-foot) bronze statue of the iconic football (soccer) player.

Even the animals at Guadalajara Zoo are taking part in the festivities, with elephants, gorillas, giraffes, capybaras, pumas, and macaws “predicting” match winners by choosing between food, shirts, boxes, soccer balls, and other items. A puma named Muluk predicted South Korea would beat Czechia by sniffing and moving a ball, one newspaper reported.

Guadalajara will host four first-round matches: South Korea vs. Czechia on June 12, Mexico vs. South Korea on June 18, Colombia vs. Democratic Republic of the Congo on June 23, and Uruguay vs. Spain on June 26.

NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. Story by Adam Voiland.

Downloads

Images of Guadalajara in 1986 (left) and 2026 (right) shows the city expanding westward into an area that had been mostly farmland. Guadalajara Stadium appears as a small circular feature on the left side of the 2026 image.

April 13, 1986

JPEG (13.09 MB)

Images of Guadalajara in 1986 (left) and 2026 (right) shows the city expanding westward into an area that had been mostly farmland. Guadalajara Stadium appears as a small circular feature on the left side of the 2026 image.

April 27, 2026

JPEG (13.71 MB)

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The post World Cup Fever in Guadalajara appeared first on NASA Science.

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World Cup Fever in Guadalajara




April 13, 1986
April 27, 2026

: Images of Guadalajara in 1986 (left) and 2026 (right) shows the city expanding westward into an area that had been mostly farmland. Guadalajara Stadium appears as a small circular feature on the left side of the 2026 image.
A pair of Landsat images shows 40 years of westward urban expansion from Guadalajara, Mexico. The Thematic Mapper on Landsat 5 captured the left image in 1986; the Operational Land Imager on Landsat 8 captured the right image in 2026.

Images of Guadalajara in 1986 (left) and 2026 (right) shows the city expanding westward into an area that had been mostly farmland. Guadalajara Stadium appears as a small circular feature on the left side of the 2026 image.
A pair of Landsat images shows 40 years of westward urban expansion from Guadalajara, Mexico. The Thematic Mapper on Landsat 5 captured the left image in 1986; the Operational Land Imager on Landsat 8 captured the right image in 2026.
NASA Earth Observatory / Lauren Dauphin

: Images of Guadalajara in 1986 (left) and 2026 (right) shows the city expanding westward into an area that had been mostly farmland. Guadalajara Stadium appears as a small circular feature on the left side of the 2026 image.
A pair of Landsat images shows 40 years of westward urban expansion from Guadalajara, Mexico. The Thematic Mapper on Landsat 5 captured the left image in 1986; the Operational Land Imager on Landsat 8 captured the right image in 2026.
Images of Guadalajara in 1986 (left) and 2026 (right) shows the city expanding westward into an area that had been mostly farmland. Guadalajara Stadium appears as a small circular feature on the left side of the 2026 image.
A pair of Landsat images shows 40 years of westward urban expansion from Guadalajara, Mexico. The Thematic Mapper on Landsat 5 captured the left image in 1986; the Operational Land Imager on Landsat 8 captured the right image in 2026.
NASA Earth Observatory / Lauren Dauphin

April 13, 1986

April 27, 2026

April 13, 1986 – April 27, 2026


A pair of Landsat images shows 40 years of westward urban expansion from Guadalajara, Mexico. The TM (Thematic Mapper) on Landsat 5 captured the left image in 1986; the OLI (Operational Land Imager) on Landsat 8 captured the right image in 2026.

Guadalajara, Mexico, was quite a different place when it last hosted World Cup games 40 years ago. The city welcomed matches in June 1986 and did so again in 2026, when South Korea faced Czechia at Guadalajara Stadium in the opening round of the 2026 FIFA World Cup.

In 1986, Guadalajara Stadium had not yet been built in Zapopan, the fast-growing municipality just northwest of Guadalajara. Many of that year’s World Cup matches were held instead at Jalisco Stadium in northeastern Guadalajara. It was in that stadium that France defeated Brazil in a penalty shootout in the 1986 quarterfinals, in what is widely regarded as one of the most memorable World Cup games of all time.

As seen in the Landsat images above, the land where Guadalajara Stadium (also called Estadio Akron) now sits was farmland in 1986. The new stadium, built in 2010 to host Mexico’s Club Deportivo Guadalajara, or Chivas, lies near the Sierra la Primavera volcanic complex, a rugged landscape full of lava flows, volcanic domes, steam vents, and hot springs. The architects who designed the stadium took inspiration from the nearby volcanic terrain, creating a structure that rises from a grassy earthen berm meant to resemble the flanks of a volcano, topped with a white roof reminiscent of a volcanic cloud.   

About 95,000 years ago, the volcanic system underneath Sierra la Primavera produced a massive eruption that caused a caldera 11 kilometers (7 miles) in diameter to slump downward. Water filled the depression for tens of thousands of years, but tectonic uplift and the accumulation of sediment eventually led to the demise of the lake. Erosion wore away the softer surrounding rock over time, leaving harder, erosion-resistant volcanic rocks within the circular feature that now stand high above the surrounding terrain.

Starting about 60,000 years ago, several lava domes erupted along the southern edge of the caldera. The youngest of them, Cerro del Colli, formed about 30,000 years ago, leaving the dome-shaped feature just south of the stadium and contributing to a broader landscape dotted with other volcanic domes and cinder cones.

Today, much of the original caldera has been preserved as a forested area known as La Primavera Biosphere Reserve, even as development has partially encircled it during the past 40 years. The population of the Guadalajara metro area has grown from about 2.7 million in 1986 to more than 5.5 million now, with particularly rapid growth in Zapopan, a burgeoning tech hub sometimes billed as “Mexico’s Silicon Valley.” A prominent development visible in Landsat images is Guadalajara Technology Park, one of several new industrial parks in Zapopan. New greenhouses have also come to the area en masse, including south of the reserve, where they are mostly used to grow fruits and vegetables.

World Cup fever runs particularly high in Guadalajara, which is hosting World Cup matches for the third time. During Brazil’s legendary title run in 1970, when Pelé led the team, Jalisco Stadium was the venue for Brazil’s first-round, quarterfinal, and semifinal matches. To commemorate him, the city in May 2026 erected a 9.5-meter (31-foot) bronze statue of the iconic football (soccer) player.

Even the animals at Guadalajara Zoo are taking part in the festivities, with elephants, gorillas, giraffes, capybaras, pumas, and macaws “predicting” match winners by choosing between food, shirts, boxes, soccer balls, and other items. A puma named Muluk predicted South Korea would beat Czechia by sniffing and moving a ball, one newspaper reported.

Guadalajara will host four first-round matches: South Korea vs. Czechia on June 12, Mexico vs. South Korea on June 18, Colombia vs. Democratic Republic of the Congo on June 23, and Uruguay vs. Spain on June 26.

NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey. Story by Adam Voiland.

Downloads

Images of Guadalajara in 1986 (left) and 2026 (right) shows the city expanding westward into an area that had been mostly farmland. Guadalajara Stadium appears as a small circular feature on the left side of the 2026 image.

April 13, 1986

JPEG (13.09 MB)

Images of Guadalajara in 1986 (left) and 2026 (right) shows the city expanding westward into an area that had been mostly farmland. Guadalajara Stadium appears as a small circular feature on the left side of the 2026 image.

April 27, 2026

JPEG (13.71 MB)

References & Resources

You may also be interested in:

Stay up-to-date with the latest content from NASA as we explore the universe and discover more about our home planet.

A Volcanic Medley Near Mammoth Lakes 

4 min read

A massive, old caldera and more recently formed craters shape the landscape in the eastern Sierra Nevada.

Article

Scoria Cones on Earth and Mars

7 min read

The hill-shaped features are a sign of explosive volcanic activity—a rarity on the Red Planet.

Article

Restless Kīlauea Launches Lava and Ash

3 min read

Episode 43 of the Hawaiian volcano’s current eruption was marked by high lava fountains and widespread ash dispersal.

Article
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Google is held liable for false information from its AI

A German court has sparked a legal controversy by ruling that Google is responsible for defamatory comments generated by its own AI system. The search giant had argued that it couldn’t be blamed for the false results, but a Munich court has deemed that not to be the case and has ruled in favor of the two unnamed plaintiffs, both publishing companies, who the Google AI Overview inaccurately said engaged in shady business practices.

Google is required to remove the comments and ensure that they are not repeated. The case is certainly going to raise some questions globally. Will this mean that other courts are going to rule against AI vendors?

Bernhard Buchner, a partner at Lausen Rechtsanwälte, the legal firm that acted for the plaintiffs, said, “I believe it shows that online providers such as Google cannot hide behind the fact that a statement was generated by AI, but rather that they can be held liable for its output. It is an important step towards ensuring that providers of AI systems have to take responsibility for their outputs.”

So, does this mean that the decision could be replicated in the US or elsewhere? Alex Shahrestani, managing partner at Austin-based Promise Legal, said, “the short answer is ‘yes’:  the Munich ruling travels, because US courts are already making the same move.”

He explained that Section 230 of the US Communications Decency Act, which has been applied to protect online service providers like social media companies from lawsuits based on their decisions to transmit or take down user-generated content, was built for computer bulletin boards, “not for a model that writes its own answers. Once the AI is the author, the company is the publisher.”

This means, he said, “businesses now need named humans at accountability nodes, verification gates before AI output ships, and audit trails that survive discovery, because ‘the model recommended it’ is a legally empty sentence.”

Does the decision mean that other AI providers could find themselves in the same position? Buchner believes it’s possible, although, he said, the situation in this case is unusual; it does not involve a classic chatbot scenario, but one where the AI-generated statements are published as an ‘AI overview’ of a search query.

“Google’s liability here is based not so much on the fact that it operates the underlying AI, but rather on the publication of its output. However, it seems entirely conceivable to me that this could also be applied generally to inaccurate or defamatory AI,” he pointed out.

Nonetheless, said Carolyn Shelby, head of SEO at Yoast, the German ruling should ensure that companies will be more circumspect in how they handle AI in the future, to protect themselves from any legal action. The first thing they should do  is to separate low-risk use of AI from major decision-making.

“Using AI to summarize meeting notes, brainstorm campaign ideas, or create a first draft of something is very different from using it to make decisions about customers, employees, finance, compliance, health, legal claims, competitive positioning, or public communications,” she noted.

She pointed out that the effects of AI use could be devastating for companies. “The consequences could include customer complaints, reputational damage, regulatory attention, legal claims, correction costs, loss of trust, and internal disruption,” she said. “Even when a mistake does not become a lawsuit, the operational cost of correcting bad information can be significant.”

However, she noted, things may not change immediately.  “Many companies will wait until there is a high-profile court case, regulatory action, or major corporate embarrassment before they take this seriously. That is usually how governance catches up with technology. But the better-run organizations will start treating AI governance as part of normal business risk management now.”

And, said Shahrestani, after the Google decision, everything has changed. It will become more important to ensure that employees remain part of the process.

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