Science
Scientists Map Miles of Wiring in a Speck of Mouse Brain
The human brain is so complex that scientific brains have a hard time making sense of it. A piece of neural tissue the size of a grain of sand might be packed with hundreds of thousands of cells linked together by miles of wiring. In 1979, Francis Crick, the Nobel-prize-winning scientist, concluded that the anatomy and activity in just a cubic millimeter of brain matter would forever exceed our understanding.
“It is no use asking for the impossible,” Dr. Crick wrote.
Forty-six years later, a team of more than 100 scientists has achieved that impossible, by recording the cellular activity and mapping the structure in a cubic millimeter of a mouse’s brain — less than one percent of its full volume. In accomplishing this feat, they amassed 1.6 petabytes of data — the equivalent of 22 years of nonstop high-definition video.
“This is a milestone,” said Davi Bock, a neuroscientist at the University of Vermont who was not involved in the study, which was published Wednesday in the journal Nature. Dr. Bock said that the advances that made it possible to chart a cubic millimeter of brain boded well for a new goal: mapping the wiring of the entire brain of a mouse.
“It’s totally doable, and I think it’s worth doing,” he said.
More than 130 years have passed since the Spanish neuroscientist Santiago Ramón y Cajal first spied individual neurons under a microscope, making out their peculiar branched shapes. Later generations of scientists worked out many of the details of how a neuron sends a spike of voltage down a long arm, called an axon. Each axon makes contact with tiny branches, or dendrites, of neighboring neurons. Some neurons excite their neighbors into firing voltage spikes of their own. Some quiet other neurons.
Human thought somehow emerges from this mix of excitation and inhibition. But how that happens has remained a tremendous mystery, largely because scientists have been able to study only a few neurons at a time.
In recent decades, technological advances have allowed scientists to start mapping brains in their entirety. In 1986, British researchers published the circuitry of a tiny worm, made up of 302 neurons. In subsequent years, researchers charted bigger brains, such as the 140,000 neurons in the brain of a fly.
Could Dr. Crick’s impossible dream be possible after all? In 2016, the American government began a $100 million effort to scan a cubic millimeter of a mouse brain. The project — called Machine Intelligence from Cortical Networks, or MICrONS — was led by scientists at the Allen Institute for Brain Science, Princeton University and Baylor College of Medicine.
The researchers zeroed in on a portion of the mouse brain that receives signals from the eyes and reconstructs what the animal sees. In the first stage of the research, the team recorded the activity of neurons in that region as it showed a mouse videos of different landscapes.
The researchers then dissected the mouse brain and doused the cubic millimeter with hardening chemicals. Then they shaved off 28,000 slices from the block of tissue, capturing an image of each one. Computers were trained to recognize the outlines of cells in each slice and link the slices together into three-dimensional shapes. All told, the team charted 200,000 neurons and other types of brain cells, along with 523 million neural connections.
For Nuno da Costa, a biologist at the Allen Institute and one of the leaders of the project, just watching the cells take shape on his computer screen was breathtaking. “These neurons are absolutely stunning — it gives me pleasure,” he said.
To understand how this mesh of neurons functioned, Dr. da Costa and his colleagues mapped the activity that had been recorded when the mouse looked at videos.
“Imagine that you come to a party that has 80,000 people, and you can be aware of every conversation, but you don’t know who is talking to whom,” Dr. da Costa said. “And now imagine that you have a way to know who is talking to whom, but you have no idea what they’re saying. If you have these two things, you can tell a better story about what’s happening at the party.”
Analyzing the data, the researchers discovered patterns in the wiring of the brain that had escaped notice until now. They identified distinct kinds of inhibitory neurons, for instance, that link only to certain other types of neurons.
“When you go into studying the brain, it seems kind of hopeless — there are just so many connections and so much complexity,” said Mariela Petkova, a biophysicist at Harvard who was not involved in the MICrONS project. “Finding wiring rules is a win. The brain is a lot less messy than people thought,” she said.
Many of the MICrONS researchers are now pitching in on a bigger project: mapping an entire mouse’s brain. With a volume of 500 cubic millimeters, a full brain would take decades or centuries to chart with current methods. The scientists will have to find additional tricks in order to finish the project in a decade.
“What they’ve already had to do to get here is heroic,” said Gregory Jefferis, a neuroscientist at the University of Cambridge who was not involved in the MICrONS project. “But we’ve still got a mountain to climb.”
Forrest Collman, a member of the MICrONS project at the Allen Institute, is optimistic. He and his colleagues recently discovered how to make microscopically thin sections from an entire mouse brain. “Some of these barriers are starting to fall,” Dr. Collman said.
But our own brain, which is about a thousand times bigger than a mouse’s, presents a much bigger challenge, he added. “The human brain right now feels like outside the range of what is possible,” he said. “We are not going there anytime soon.”
But Sebastian Seung, a neuroscientist at Princeton and a member of the MICrONS project, noted that mouse brains and human brains are similar enough that researchers might glean clues that could help them find medications to effectively treat psychological disorders without causing harmful side effects.
“Our current methods of manipulating the nervous system are incredibly blunt instruments,” Dr. Seung said. “You put in a drug, and it goes everywhere,” he added. “But being able to actually reach in and manipulate a cell type — that’s precision.”
The efforts to map a whole mouse brain are supported by funding from a long-running National Institutes of Health program called the BRAIN initiative. But the future of the endeavor is uncertain. Last year, Congress cut funding to the BRAIN initiative by 40 percent, and last month President Trump signed a bill cutting support by another 20 percent.
Dr. Bock noted that brain-mapping efforts like MICrONS take years, partly because they require the invention of new technologies and software along the way.
“We need consistency and predictability of science funding to realize these long-term goals,” Dr. Bock said.
new video loaded: Pentagon Releases U.F.O. Files
By Jorge Mitssunaga
May 8, 2026
President Trump has signed off on a plan to fire Dr. Marty Makary, commissioner of the Food and Drug Administration, after a series of clashes over vaping, oversight of the abortion pill and a series of new drug application denials that rattled biotech companies, according to a person briefed on the matter, who was not authorized to discuss it publicly.
Dr. Makary had a high profile for an F.D.A. commissioner, appearing frequently on television and podcasts to sell the work he was doing at the agency on improving the food supply, speeding up some drug approvals and trying to restore agency morale after thousands of staff members left.
He tried to walk the tightrope between the business-friendly Make America Great Again movement, pledging to get rid of regulations that slow down innovation and to attract more drug trials to the United States. He was an ally of Health Secretary Robert F. Kennedy Jr.’s Make American Healthy Again supporters, voicing the skepticism of the pharmaceutical industry and authorizing natural food dyes.
Ultimately, Dr. Makary’s efforts were not enough to overcome the grievances of a growing band of enemies focused on selling tobacco, opposing abortion and seeing biotech therapies authorized.
Mr. Trump’s decision to dismiss him was first reported by The Wall Street Journal.
The decision could still change, given Mr. Trump’s propensity to change his mind Dr. Makary has also proven persuasive with Mr. Trump in beating back previous efforts to oust him.
Leaving the White House Friday evening, Mr. Trump dismissed the idea that Dr. Makary would be fired.
“I’ve been reading about it, but I know nothing about it,” he said.
The White House has pressured Dr. Makary for months to authorize flavored e-cigarettes, according to a person close to the conversations. The approvals were a top wish of major tobacco companies that have been top donors to Mr. Trump. In March, the F.D.A. issued a memo saying that it would only authorize e-cigarettes in flavors such as mint, tea and spices. The memo said the fruit and candy flavors would be unlikely to pass muster, given their appeal to young people.
Pressure continued, though, and on Tuesday the F.D.A. authorized blueberry and mango flavored e-cigarettes by Glas, a small company based in Los Angeles.
Abortion foes including Susan B. Anthony Pro-Life America have continued to turn up the heat on Dr. Makary, reiterating their call for his firing on Thursday. The group’s leaders and others view Dr. Makary as dragging his feet on a safety review of the abortion pill mifepristone, which they viewed as a way to highlight what they believe are dangers of the drug. Former Vice President Mike Pence, who also opposes abortion rights, amplified criticism of Dr. Makary on social media as well.
The administration has been under pressure from conservatives to tighten regulations on the prescribing and dispensing of mifepristone. The Supreme Court is reviewing a federal appeals court ruling that temporarily blocked abortion providers from prescribing the drug through telemedicine and sending it to patients by mail.
Biotech companies and their investors have also raised alarms with the White House about agency decisions to reject a series of treatments for rare diseases. The F.D.A. typically turns down about 20 percent of the applications it receives for drug approvals from companies.
Dr. Makary has been aggressive in defending the decisions, which he said came from career scientists who found the medications ineffective.
Dr. Makary also had to contend with a health secretary who seemed to view the F.D.A. as an avenue for getting his favored products authorized, exemplified by Mr. Kennedy’s social media post saying that the agency would end its “war on” stem cell treatments, peptides and raw milk. Mr. Kennedy pushed the F.D.A. to reverse a 2023 ban and allow the use of a number of peptides, unproven compounds purported to offer anti-aging or muscle-recovery benefits.
Before leading the F.D.A., Dr. Makary was a cancer surgeon and health policy researcher at Johns Hopkins University School of Medicine. He was also the author of several books about the health care system.
Some of Dr. Makary’s more popular moves included encouraging broader use of hormone replacement products for women and lifting the F.D.A.’s warnings on them. He helped speed some promising drugs to market, including a pancreatic cancer therapy and the pill form of the popular GLP-1 weight loss drugs.
Some California residents were among the 147 passengers and staff aboard a luxury cruise ship stricken by a suspected outbreak of hantavirus that has left three people dead and several others severely ill, officials confirmed Thursday.
California public health officials say they are monitoring the situation after being notified by the U.S. Centers for Disease Control and Prevention that some state residents were passengers on the MV Hondius. The precise status of those individuals, however, remains murky.
Hantavirus is a rare but deadly disease that attacks the lungs and is typically contracted by humans through inhalation of particles contaminated with the urine, feces or saliva of a wild rodent.
However, Dr. Tedros Adhanom Ghebreyesus, director-general of the World Health Organization, confirmed Thursday that the Andes virus — a form of hantavirus that can spread from person to person — was involved in the outbreak.
Here’s what we know:
The MV Hondius cruise ship anchored at a port in Praia, Cape Verde, on Wednesday.
(Misper Apawu / Associated Press)
As its name suggests, the Andes virus is typically found in South America. The Dutch-flagged MV Hondius was on a 46-day journey that traveled from Antarctica with stops in Argentina.
In the case of human-to-human transmission, a person would first be infected by a wild rodent’s contaminated particles and then pass the infection to someone else, said Dr. Gaby Frank, director of the Johns Hopkins Special Pathogens Center.
“In previous outbreaks of Andes virus, transmission between people has been associated with close and prolonged contact, particularly among household members, intimate partners and people providing medical care,” Ghebreyesus said. “That appears to be the case in the current situation.”
None of the remaining passengers or crew members on the ship are symptomatic, he said.
The ship was not permitted to allow passengers to disembark at its original destination, Cape Verde, and is sailing for Spain’s Canary Islands.
“I want to be unequivocal here: This is not SARS-CoV-2. This is not the start of a COVID pandemic. This is an outbreak that we see on a ship. There’s a confined area,” Dr. Maria Van Kerkhove, who leads the WHO’s epidemic and pandemic management, said at a briefing. “This is not the same situation we were in six years ago. It doesn’t spread the same way like coronaviruses do.”
California passengers on the cruise
On April 1, 114 guests boarded the cruise ship in Ushuaia, Argentina. Twenty-three days later, 30 passengers — including six people from the United States — disembarked on a stop in St. Helena, a remote island about 1,100 miles off the coast of Africa, according to the cruise operator Oceanwide Expeditions.
Public health agencies in California, Georgia and Arizona were notified by the CDC that some of their residents were among the passengers on the cruise. It’s unclear whether these individuals disembarked on April 24, however.
The CDC is assisting local health authorities with monitoring California residents who were aboard the cruise, according to a statement by the California Department of Public Health on Friday.
As of Friday, one passenger has returned to their California residence and is in contact with local public health officials, and at least one other remains aboard the ship, according to the state agency.
“We understand that news of an unusual outbreak can be concerning,” said Dr. Erica Pan, director of the California Department of Public Health. “Unlike influenza and COVID-19, years of experience in South America have shown that this Andes hantavirus rarely spreads between people.”
Officials said the current public health protocol is to do daily symptom monitoring and reporting.
“As there are no known cases of Andes hantavirus infection from people without symptoms, and any spread has usually been limited to people with prolonged close contact with an ill person with this virus, the risk to the general public in California is extremely low,” the agency said in a statement.
In a statement earlier this week, the CDC also said that the risk to the American public “is extremely low” at this time.
“We urge all Americans aboard the ship to follow the guidance of health officials as we work to bring you home safely,” the agency said.
The others who exited the ship on April 24 were individuals from Canada, Denmark, Germany, the Netherlands, New Zealand, Switzerland, Sweden, Singapore, St. Kitts and Nevis, Turkey and the United Kingdom.
Of the remaining passengers still aboard the ship headed for Spain’s Canary Islands, California Department of Public Health said none were ill as of Friday.
How many people have been infected?
The number of lab-confirmed hantavirus cases has risen to five, according to the WHO. There are three additional suspected cases.
A timeline of reported cases of hantavirus aboard the cruise ship can be found here.
The WHO is monitoring reports of other people with symptoms “who may have had contact with one of the passengers. In each case, we are in close contact with the relevant authorities,” Tedros said.
The first passenger to have been infected, a Dutchman, became sick aboard the cruise ship on April 6 and died on April 11.
No samples were taken, because his symptoms were similar to other respiratory diseases. His widow left the ship with his body on April 24 during the scheduled stop at St. Helena.
“She deteriorated during a flight to Johannesburg on the 25th of April and died the next day,” Tedros said.
Before boarding the cruise ship, the Dutch couple had traveled through Argentina, Chile and Uruguay on a bird-watching trip, “which included visits to sites where the species of rat that is known to carry Andes virus was present,” Tedros said.
After leaving the ship, the woman was briefly aboard a KLM aircraft in Johannesburg bound for Amsterdam but was barred from the flight due to her medical condition, the airline said in a statement.
Dutch news outlets reported that a flight attendant on a KLM airplane — who briefly had contact with the widow — started feeling sick and had mild symptoms and was in isolation at a hospital in Amsterdam.
The flight attendant has since tested negative for the Andes virus, Dr. Jeremy Faust, an emergency medicine physician, wrote on his Substack blog, Inside Medicine, citing a text message sent to him by Tedros.
“It is still possible that the flight attendant contracted the Andes virus. However, given our understanding of the virus, this information means that the flight attendant’s symptoms are not caused by the Andes hantavirus, but by some other medical illness,” Faust wrote.
More cases may be reported, because the incubation period — the time it takes between exposure to the virus and the onset of illness — for the Andes strain of the hantavirus is up to six weeks.
What we know about hantavirus
There are roughly 50 identified species of hantavirus. The virus that’s found in the Americas tends to cause a cardiopulmonary syndrome, a condition that affects the heart and the lungs, according to Frank.
There have been 890 laboratory-confirmed cases of hantavirus disease reported in the U.S. since surveillance began in 1993, according to the most recent data from the CDC.
From 1980 to 2025, 99 California residents have been diagnosed with a hantavirus infection, according to the California Department of Public Health.
CDC officials said 38% of people who develop respiratory symptoms may die from the disease.
Still, the data suggest that contracting hantavirus is rare, said Dr. Afif El-Hasan, member of the American Lung Assn.’s national board of directors.
There is no vaccine or specific antiviral medicine for hantavirius.
Intensive-care treatment may include intubation and oxygen therapy, fluid replacement and use of medications to lower blood pressure, according to the American Lung Assn.
The signs of hantavirus
Early symptoms of hantavirus are similar to the flu and include fatigue, fever and muscle aches, according to the CDC. Symptoms start to develop within one to eight weeks after contact with an infected rodent.
Half of those who contract the virus also experience headaches, dizziness, chills, nausea, vomiting, diarrhea and abdominal pain.
Four to 10 days after the initial phase of the illness, another round of symptoms can develop, which include coughing, shortness of breath and possible tightness in the chest as the lungs fill with fluid.
Even though contracting hantavirus in the U.S. continues to be a rare event, El-Hasan said, people should take these initial symptoms seriously and promptly seek medical care.
How to protect yourself
Hantavirus cases can occur year-round, but the peak seasons in the United States are the spring and summer, which coincide with the reproductive seasons for deer mice.
To lessen your risk of infection, keep wild rodents out of your home and other enclosed spaces by sealing any holes and placing snap traps.
If you find evidence of mice, wear personal protective equipment and disinfect the area. When you’re done, put everything, including cleaning materials, in a bag and toss it in your trash bin.
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