Aha Moments - Brain Organoids - Sensory Input in Developing Cortex

[Breedlove, S]

https://www.quantamagazine.org/how-your-brain-creates-aha-moments-and-why-they-stick-20251105/

 How Your Brain Creates ‘Aha’ Moments and Why They Stick

By Nora Bradford

Here are three words: pine, crab, sauce. There’s a fourth word that combines with each of the others to create another common word. What is it?

When the answer finally comes to you, it’ll likely feel instantaneous. You might even say “Aha!” This kind of sudden realization is known as insight, and a research team recently uncovered how the brain produces it (opens a new tab), which suggests why insightful ideas tend to stick in our memory.

Maxi Becker (opens a new tab), a cognitive neuroscientist at Duke University, first got interested in insight after reading the landmark 1962 book The Structure of Scientific Revolutions (opens a new tab) by the historian and philosopher of science Thomas Kuhn. “He describes how some ideas are so powerful that they can completely shift the way an entire field thinks,” she said. “That got me wondering: How does the brain come up with those kinds of ideas? How can a single thought change how we see the world?”

Such moments of insight are written across history. According to the Roman architect and engineer Vitruvius, in the third century BCE the Greek mathematician Archimedes suddenly exclaimed “Eureka!” after he slid into a bathtub and saw the water level rise by an amount equal to his submerged volume (although this tale may be apocryphal (opens a new tab)). In the 17th century, according to lore, Sir Isaac Newton had a breakthrough in understanding gravity after an apple fell on his head. In the early 1900s, Einstein came to a sudden realization that “if a man falls freely, he would not feel his weight,” which led him to his theory of relativity, as he later described in a lecture.

Insights are not limited to geniuses: We have these cognitive experiences all the time when solving riddles or dealing with social or intellectual problems. They are distinct from analytical problem-solving, such as the process of doing formulaic algebra, in which you arrive at a solution slowly and gradually as if you’re getting warmer. Instead, insights often follow periods of confusion. You never feel as if you’re getting warmer; rather, you go from cold to hot, seemingly in an instant. Or, as the neuropsychologist Donald Hebb, known for his work building neurobiological models of learning, wrote in the 1940s, sometimes “learning occurs as a single jump, an all-or-none affair.”

 © 2025 Simons Foundation


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https://www.nytimes.com/2025/11/06/science/brain-organoids-neurons.html

What We Can Learn From Brain Organoids

By Carl Zimmer

In Paola Arlotta’s lab at Harvard is a long, windowless hallway that is visited every day by one of her scientists. They go there to inspect racks of scientific muffin pans. In every cavity of every pan is a pool of pink liquid, at the bottom of which are dozens of translucent nuggets no bigger than peppercorns.

The nuggets are clusters of neurons and other cells, as many as two million, normally found in the human brain. On their daily rounds, the scientists check that the nuggets are healthy and well-fed.

“No first-year students walk in that corridor,” Dr. Arlotta said. “You have to be experienced enough to go there, because the risk is very high that you’re going to mess up the work that took years to build.”

The oldest nuggets are now seven years old. Back in 2018, Dr. Arlotta and her colleagues created them from skin cells originally donated by volunteers. A chemical cocktail transformed them into the progenitor cells normally found in the fetal human brain.

The cells multiplied into neurons and other types of brain cells. They wrapped their branches around each other and pulsed with electrical activity, much like the pulses that race around inside our heads. One such nugget can contain more neurons than the entire brain of a honeybee. But Dr. Arlotta is quick to stress that they are not brains. She and her colleagues call them brain organoids.

“It’s so important to call them organoids and not brains, because they’re no such thing,” she said. “They are reductionist replicas that can show us some things that are the same, and many others that are not.”

And yet the similarities are often remarkable, as Dr. Arlotta and her colleagues recently demonstrated in a new report on their long-lived organoids.

After the organoids started growing in 2018, their neurons began behaving like the those in a fetal human brain, down to way their genes switched on and off. And as the months passed, the neurons matured to resemble the neurons in a baby after birth.

    © 2025 The New York Times Company


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https://www.nature.com/articles/d41586-025-03641-0

First-ever atlas of brain development shows how stem cells turn into neurons

    Miryam Naddaf 

Scientists have created the most detailed maps yet of how our brains differentiate from stem cells during embryonic development and early life. In a Nature collection including five papers published yesterday, researchers tracked hundreds of thousands of early brain cells in the cortices of humans and mice, and captured with unprecedented precision the molecular events that give rise to a mixture of neurons and supporting cells.

“It’s really the initial first draft of any ‘cell atlases’ for the developing brain,” says Hongkui Zeng, executive vice-president director of the Allen Institute for Brain Science in Seattle, Washington, and a co-author of two papers in the collection.

These atlases could offer new ways to study neurological conditions such as autism and schizophrenia. Researchers can now “mine the data, find genes that may be critical for a particular event in a particular cell type and at a particular time point”, says Zeng. “We have a very exciting time coming,” adds Zoltán Molnár, a developmental neuroscientist at the University of Oxford, UK, who was not involved with any of the studies.

The work is part of the BRAIN Initiative Cell Atlas Network (BICAN) — a project launched in 2022 by the Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative at the US National Institutes of Health with US$500 million in funding to build reference maps of mammalian brains.
Patterns of development

Two of the papers map parts of the mouse cerebral cortex — the area of the brain involved in cognitive functions and perception.

Zeng and her colleagues focused on how the visual cortex develops from 11.5-day-old embryos to 56-day-old mice. They created an atlas of 568,654 individual cells and identified 148 cell clusters and 714 subtypes1. “It’s the first complete high-resolution atlas of the cortical development, including both prenatal and postnatal” phases, says Zeng.

© 2025 Springer Nature Limited

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https://www.thetransmitter.org/spectrum/constellation-of-studies-charts-brain-development-offers-dramatic-revision/

 Constellation of studies charts brain development, offers ‘dramatic revision’

By Holly Barker

Multiple mouse and human brain atlases track the emergence of distinct cell types during development and uncover some of the pathways that decide a cell’s fate. The findings were published today in a collection of Nature papers.

The papers highlight the timing and location of cell diversification and offer fresh insights into the evolution of those cells. Neuronal subtypes emerge at starkly different times in distinct brain regions, according to multiple mouse studies. And the work upends ideas about cell migration, including the notion that a portion of cortical neurons are made on site, developmental maps of the human brain suggest. 

“This is a dramatic revision of the fundamental principles that we thought were true in the cerebral cortex,” says Tomasz Nowakowski, associate professor of neurological surgery, anatomy and psychiatry, and of behavioral sciences, at the University of California, San Francisco and an investigator on one of the new studies.

The special issue comprises 12 papers—including 6 newly published ones—from groups working as part of the BRAIN Initiative Cell Atlas Network. The work builds on the network’s complete cell census, published in 2023, that cataloged 34 classes and 5,322 unique cell types in the adult mouse brain.

“Those cell types don’t appear out of a vacuum at the same time,” says Nowakowski, who co-authored a commentary on the new collection. Pinpointing when those cells emerge and where they originate from was the “obvious next question,” he says.

At birth, the mouse brain contains all the initial cell classes that diversify into the multitude of neurons and glia found in older rodents. But precisely when that diversification occurs varies among brain regions: In the visual cortex, new cell types emerge weeks after birth and peak twice—once when the animal first opens its eyes and then again at the onset of the critical period, according to one study.

© 2025 Simons Foundation
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