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Pasca Lab at Stanford University
Pasca Lab at Stanford University

Scientists Grow Working Human Brain Circuits

Pasca Lab at Stanford University
Pasca Lab at Stanford University

Researchers at the Stanford University School of Medicine have successfully grown the first-ever working 3D brain circuits in a petri dish. Writing in the journal Nature, they say the network of living cells will allow us to study how the human brain develops.

Scientists have been culturing brain cells in the lab for some time now. But previous projects have produced only flat sheets of cells and tissue, which can’t really come close to recreating the three-dimensional conditions inside our heads. The Stanford researchers were especially interested in the way brain cells in a developing fetus can join up together to create networks.

“We’ve never been able to recapitulate these human-brain developmental events in a dish before,” senior author Sergiu Pasca, MD said in a statement.

Studying real-life pregnant women and their fetuses can also be ethically and technically tricky, which means there’s still a lot about our journey into the world that we don’t know.

“[This] process happens in the second half of pregnancy, so viewing it live is challenging,” Pasca said.

The latest project builds on earlier work from Pasca and his colleagues. In 2015, they devised a way to encourage pluripotent stem cells to grow, not into flat sheets, but into dense little spheres that can connect in three dimensions. The researchers used these spheres to grow two types of neurons, each found in a different region of the brain. Once the cells were functional, the researchers gently introduced the two groups to one another and watched to see what would happen.

Two cell groups, playing nice. Image credit: Pasca Lab at Stanford University

The results were extraordinary. Within three days, the two batches had begun reaching toward and networking with one another. Experiments on the new circuits showed that the still-growing cells were sending signals back and forth, strengthening connections between two areas of the brain. It was like watching a brain come into being.

“Our method of assembling and carefully characterizing neuronal circuits in a dish is opening up new windows through which we can view the normal development of the fetal human brain,” said Pasca. “More importantly, it will help us see how this goes awry in individual patients.”

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Jamie McCarthy/Getty Images for Bill & Melinda Gates Foundation
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Medicine
Bill Gates is Spending $100 Million to Find a Cure for Alzheimer's
Jamie McCarthy/Getty Images for Bill & Melinda Gates Foundation
Jamie McCarthy/Getty Images for Bill & Melinda Gates Foundation

Not everyone who's blessed with a long life will remember it. Individuals who live into their mid-80s have a nearly 50 percent chance of developing Alzheimer's, and scientists still haven't discovered any groundbreaking treatments for the neurodegenerative disease [PDF]. To pave the way for a cure, Microsoft co-founder and philanthropist Bill Gates has announced that he's donating $100 million to dementia research, according to Newsweek.

On his blog, Gates explained that Alzheimer's disease places a financial burden on both families and healthcare systems alike. "This is something that governments all over the world need to be thinking about," he wrote, "including in low- and middle-income countries where life expectancies are catching up to the global average and the number of people with dementia is on the rise."

Gates's interest in Alzheimer's is both pragmatic and personal. "This is something I know a lot about, because men in my family have suffered from Alzheimer’s," he said. "I know how awful it is to watch people you love struggle as the disease robs them of their mental capacity, and there is nothing you can do about it. It feels a lot like you're experiencing a gradual death of the person that you knew."

Experts still haven't figured out quite what causes Alzheimer's, how it progresses, and why certain people are more prone to it than others. Gates believes that important breakthroughs will occur if scientists can understand the condition's etiology (or cause), create better drugs, develop techniques for early detection and diagnosis, and make it easier for patients to enroll in clinical trials, he said.

Gates plans to donate $50 million to the Dementia Discovery Fund, a venture capital fund that supports Alzheimer's research and treatment developments. The rest will go to research startups, Reuters reports.

[h/t Newsweek]

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science
Eye Doctors Still Use This 100-Year-Old Test for Color Blindness

You may have seen them at your ophthalmologist's office: large circular diagrams made up of colored dots. People with normal vision are able to discern a number among the dots of contrasting colors. People who are color blind might see only a field of spots.

These elegant, deceptively modern drawings were published 100 years ago by a Japanese ophthalmologist, Shinobu Ishihara. Thanks to the designs' simplicity and diagnostic accuracy, the Ishihara test is still the most popular and efficient way to identify patients with color vision deficiencies.

Born in Tokyo in 1879, Ishihara studied medicine at the prestigious Tokyo Imperial University on a military scholarship, which required him to serve in the armed forces. After graduating in 1905, he worked for three years as a physician specializing in surgery in the Imperial Japanese Army, and then returned to the university for postgraduate studies in ophthalmology. In his research, Ishihara focused on identifying and recruiting soldiers with superior vision, thereby increasing the overall effectiveness of the military. And that became of prime importance to Japan beginning in 1914.

As World War I spread across Europe, Asia, and the Pacific, the Japanese army asked Ishihara to develop a better way to screen draftees for color vision problems. The most popular method at the time was the Stilling test, invented by German ophthalmologist Jakob Stilling in 1878 as the first clinical color vision test. (Previous tools had asked patients to identify the colors of wool skeins or illuminated lanterns—useful skills for sailors and railway conductors, but an imprecise method for diagnosing vision issues.)

"Though popular, 'the Stilling' retained a distinctly 19th-century flavor, more treatise-like and less diagnostically incisive," according to Eye magazine.


Shinobu Ishihara
Wellcome Images // CC BY 4.0

Japanese army officials requested a new diagnostic tool that was easier to administer and interpret. The test Ishihara began to develop was based, like Stilling's, on the principle of pseudo-isochromatism—a phenomenon in which two or more colors are seen as the same (or isochromatic) when they're actually different. A person with normal vision could easily see the difference, while people with red-green deficiency, the most common form of color blindness, would have difficulty distinguishing those two opposing colors. Those with blue-yellow color blindness, a less common type, would have a hard time discerning reds, greens, blues, or yellows.

Ishihara hand-painted circular designs comprised of small dots of different areas and colors so that variations in the design could be discerned only by color and not shape, size, or pattern. Hidden in the field of dots was a figure of a contrasting color that people with normal vision could see, while those with deficiencies could not. Other plates in the series were designed to show figures that would be visible only to people with deficiencies. When physicians displayed the diagrams, patients said or traced the visible figure within the circle without needing to use ambiguous color names, which standardized the possible results.

The earliest sets of Ishihara plates, produced in 1916, were reserved exclusively for the army's use and featured Japanese characters within the diagrams. In 1917, in an effort to sell the series internationally, Ishihara redesigned it with the now-familiar Arabic numerals and published a set of 16 plates as Tests for Colour Deficiency.

The tests were adopted throughout the world beginning in the early 1920s, and eventually grew into a set of 38 plates. But their popularity almost led to their undoing. Unauthorized publishers printed their own version of the plates to meet demand, throwing the accuracy of the diagnostic colors into doubt. "The plates have been duplicated along with an easily memorized key by cheap color processes in the tabloid press, and exposed in public places, reducing the fifth edition [of the collection] to a parlor game," one psychologist warned in the Journal of the Optical Society of America in 1943.

Despite those obstacles, the tests proved indispensable for both practicing physicians and researchers. Ishihara continued to refine the designs and improve the color accuracy of the images into the late 1950s, while he also served as the chair of the ophthalmology department and then dean of the medical school at Tokyo Imperial University. In addition to Tests for Colour Deficiency, he also published an atlas, textbook, lectures, and research studies on eye diseases. But he is remembered most for the iconic charts that seamlessly blend art and science.

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