Neuroscience 2025 - Dual Sleep - Epigenetics - Taking Testosterone

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Dec 31, 2025, 7:00:21 AM12/31/25

https://www.npr.org/2025/12/27/nx-s1-5647682/what-we-have-learned-about-neuroscience-in-2025

What we have learned about neuroscience in 2025

Jon Hamilton

SCOTT SIMON, HOST:

And it has been a banner year in brain science. We've learned that lifestyle changes really can keep your brain young and that electrical pulses can help with rheumatoid arthritis, and that LSD can relieve anxiety and depression. Scientists even managed to replicate a human brain network that carries pain signals. NPR science correspondent Jon Hamilton joins us. Jon, thanks so much for being with us.

JON HAMILTON, BYLINE: Hi, Scott.

SIMON: Well, let's start with that brain network. What does it do?

HAMILTON: Well, it recreates the pathway that carries brain signals from, say, your fingertip to the part of the brain that says, you know, ouch, that hurts. And that pathway has several sort of relay stations along the way. So a team at Stanford decided to recreate those stations using brain organoids, which are these pea-sized clumps of human brain cells that can mimic different types of brain tissue. In this case, the scientists used four different organoids representing the four types of nerve cells that relay pain signals. And when they put these organoids together in a dish, they spontaneously wired up to form the entire pain pathway.

SIMON: That sounds extraordinary, but I have to ask - can you tell if the organoids in a dish felt anything?

HAMILTON: You can, and the way you can tell is with red hot chile peppers. The scientists took the organoid that was acting like a nerve ending, and they exposed it to chemicals like the ones in hot chile peppers, you know, that burn your mouth. Here is Dr. Sergiu Pasca explaining what happened.

SERGIU PASCA: We discovered that if you start adding some of these compounds that are inducing inflammatory responses of pain, then you start seeing that information traveling. The neurons that sends these signals get activated. And they transmit that information to the next station and the next station, all the way to the cortex.

HAMILTON: There's good reason for this research, too. It's part of an effort to help people with chronic pain.

SIMON: Let's move on to the whole question of trying to keep your brain young. Like, can you really do that?

HAMILTON: Why, yes, you can. At least according to a really big study funded by the Alzheimer's Association. This study involved about 2,000 people in their 60s and 70s, and they were all pretty sedentary, at least at the beginning. Half of these people spent two years getting aerobic exercise at the gym, eating a Mediterranean diet, watching their blood pressure and taking part in this really demanding cognitive training program. The other people - they were just told to eat better and exercise more. At the end of the study, the people in the hardcore program did better on tests of thinking and memory. And their scores were actually as good as those from people a year or two younger than they were.

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https://www.thetransmitter.org/sleep/snoozing-dragons-stir-up-ancient-evidence-of-sleeps-dual-nature/

Snoozing dragons stir up ancient evidence of sleep’s dual nature

By Lauren Schenkman

In pursuit of the brain’s secrets, neuroscientist Paul-Antoine Libourel has traveled to the ends of the earth. But during the COVID-19 lockdown in 2020, he worked closer to home—in his own darkened garage in Lyon, filming a sleeping chameleon.

Libourel, a researcher at the Center for Functional and Evolutionary Ecology in Montpelier, had heard that chameleons lose their ability to camouflage during sleep. But as the hours passed in his garage, he observed something extraordinary: The chameleon’s skin fluctuated from bright to dark to bright again every few minutes.

This strobing skin display, Libourel and his colleagues have since discovered, reflects an inner rhythm. The chameleon’s brain activity alternates between waves of higher and lower amplitude, synchronized with increased and decreased eye movements, plus changes in the animal’s heart rate and breathing rate. Six other species of lizard, including bearded dragons—along with rats, mice, pigeons and humans—show the same “infraslow fluctuations” in EEG activity during non-REM sleep, according to a study Libourel’s team published today in Nature Neuroscience.

Because reptiles and mammals diverged about 320 million years ago, the findings mean these cycles “are a central thing, maybe a core building block of sleep,” says study investigator Antoine Bergel, research director at the Centre National de la Recherche Scientifique. They also raise the question of why these rhythms are so conserved, Bergel and Libourel say, and hint at how sleep has evolved.

The sleep field, which tends to focus on mice and humans, needed this type of comparative study, says Philippe Mourrain, associate professor of psychiatry and behavioral sciences at Stanford University, who studies sleep in zebrafish but was not involved in the new work. “It’s a tour de force to do science on nonconventional species.”

https://www.quantamagazine.org/how-dads-fitness-may-be-packaged-and-passed-down-in-sperm-rna-20251222/

How Dad’s Fitness May Be Packaged and Passed Down in Sperm RNA

By Ivan Amato

The standard sperm-meets-egg story posits that sperm cells are hardly more than bundles of shrink-wrapped DNA with tails. Their mission is simple: Deliver a father’s genes into a mother’s egg for sexual reproduction. Just about all other aspects of a developing embryo, including its cellular and environmental components, have nothing to do with dad. Those all come from mom.

But nearly two decades of studies from multiple independent labs threaten to rewrite that story. They suggest that dad’s gametes shuttle more than DNA: Within a sperm’s minuscule head are stowaway molecules, which enter the egg and convey information about the father’s fitness, such as diet, exercise habits and stress levels, to his offspring. These non-DNA transfers may influence genomic activity that boots up during and after fertilization, exerting some control over the embryo’s development and influencing the adult they will become.

The findings, so far largely described in mouse models, could end up changing the way we think about heredity. They suggest “that what we do in this life affects the next generation,” said Qi Chen (opens a new tab), a reproductive and developmental biologist at the University of Utah Medical School who is among the pioneers of this research. In other words: What a father eats, drinks, inhales, is stressed by or otherwise experiences in the weeks and months before he conceives a child might be encoded in molecules, packaged into his sperm cells and transmitted to his future kid. The researchers have largely zeroed in on RNA molecules, those short-lived copies of DNA that reflect genetic activity at a given time.

It’s a tantalizing notion. But the mechanistic details — how experience is encoded, how it’s transferred from sperm to egg, and whether and how it affects a developing embryo — are not easy to unpack, especially given the challenges of conducting research in human subjects. For this reason, and because of the potentially textbook-rewriting implications of the findings, researchers, including those spearheading the work, are cautious about overselling their results.

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https://www.nytimes.com/2025/12/26/magazine/what-its-like-when-your-wife-goes-on-testosterone.html

What It’s Like When Your Wife Goes on Testosterone

By Susan Dominus

After years of a marriage that had little sex in it, Greg Carter had largely accepted that his wife no longer had any interest. The last thing he expected was that right around the time that they both were nearing 50, his wife would have a complete change of heart. “She was pouncing on me,” he said.

His wife had recently started taking testosterone to manage her menopausal symptoms — at a dose so high that it brought her testosterone levels higher than is typical even for women in their 20s. The difference in her desire was almost immediate. “I had the experience of feeling like a teenage boy,” she told me. The shift vastly improved Greg’s own happiness, so much so that he sometimes felt pangs of regret about the years they spent together without a sex life. “I realized, later in life, all that we had missed out on,” he says.

Earlier this year, I published an article on how women are increasingly — with widely varying results — seeking out testosterone to help them with energy or their sex lives. Some women who take testosterone at relatively low doses approved by major medical societies feel little change in their bodies, while others see an increase in their desire. Women who take high doses — doses that exceed levels approved by major medical societies — often report sharp upticks in their interest in sex.

Franny’s doctor prescribed her testosterone (along with estrogen and progesterone) in what’s known as a pellet, a small medical product the size of a grain of rice that is inserted beneath the skin. Often those pellets, which release hormones over the course of several months, provide doses of testosterone that bring their levels much higher than those that women would have naturally — which was true in Franny’s case.

“I feel like I want it sometimes more than my husband,” Franny told me when I was reporting my original article. There was a hint of nervousness in her tone of voice — that dynamic was a shift from their norm and one that made me realize it wasn’t just Franny’s life that had changed, but also Greg’s. And that made me wonder what it would be like to be the partner of someone who was undergoing such a radical shift.

https://www.npr.org/sections/shots-health-news/2025/12/27/nx-s1-5658291/adhd-adderall-ritalin-mechanism

ADHD drugs may work indirectly to boost attention

Jon Hamilton

Scientists are updating their view of how drugs like Adderall and Ritalin help children with attention deficit hyperactivity disorder stay on task.

The latest evidence is a study of thousands of brain scans of adolescents that confirms earlier hints that stimulant drugs have little direct impact on brain networks that control attention.

Instead, the drugs appear to activate networks involved in alertness and the anticipation of pleasure, scientists report in the journal Cell.

"We think it's a combination of both arousal and reward, that kind of one-two punch, that really helps kids with ADHD when they take this medication," says Dr. Benjamin Kay, a pediatric neurologist at Washington University School of Medicine in St. Louis and the study's lead author.

The results, along with those of smaller studies, support a "mindset shift about what stimulants are doing for people," says Peter Manza, a neuroscientist at the University of Maryland who was not involved in the research.

The new research analyzed data from the Adolescent Brain Cognitive Development Study, a federally funded effort that includes brain scans of nearly 12,000 children. About 4% of these kids had ADHD when they entered the study, and nearly half of those were on a prescription stimulant.

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https://www.theguardian.com/society/2025/dec/30/two-new-subtypes-of-ms-found-in-exciting-breakthrough

Two new subtypes of MS found in ‘exciting’ breakthrough

Andrew Gregory Health editor

Scientists have discovered two new subtypes of multiple sclerosis with the aid of artificial intelligence, paving the way for personalised treatments and better outcomes for patients.

Millions of people have the disease globally – but treatments are mostly selected on the basis of symptoms, and may not be effective because they don’t target the underlying biology of the patient.

Now, scientists have detected two new biological strands of MS using AI, a simple blood test and MRI scans. Experts said the “exciting” breakthrough could revolutionise treatment of the disease worldwide.

In research involving 600 patients, led by University College London (UCL) and Queen Square Analytics, researchers looked at blood levels of a special protein called serum neurofilament light chain (sNfL). The protein can help indicate levels of nerve cell damage and signal how active the disease is.

The sNfL results and scans of the patients’ brains were interpreted by a machine learning model, called SuStaIn. The results, published in medical journal Brain, revealed two distinct types of MS: early sNfL and late sNfL.

In the first subtype, patients had high levels of sNfL early on in the disease, with visible damage in a part of the brain called the corpus callosum. They also developed brain lesions quickly. This type appears to be more aggressive and active, scientists said.

In the second subtype, patients showed brain shrinkage in areas like the limbic cortex and deep grey matter before sNfL levels went up. This type seems to be slower, with overt damage occurring later.

Researchers say the breakthrough will enable doctors to more precisely understand which patients are at higher risk of different complications, paving the way for more personalised care.

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