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Kaleidoscopic image of a mouse’s brain is 64 million times sharper than a typical MRI

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Scientists recently boosted the resolution of magnetic resonance imaging (MRI) to 64 million times higher than normal. They used the technique to take captivating, high-definition images of a mouse brain, showing the organ like never before.

While the swirly, psychedelic images are that of a rodent’s brain, the research team thinks humans could be next to undergo one of these newly enhanced brain scans. The technology could help doctors detect changes to the human brain that occur due to neurodegenerative diseases, such as Alzheimer’s disease, as well as changes linked to healthy aging.

The mouse scan was shared as part of a new paper published April 17 in the journal PNAS (opens in new tab).

“It is something that is truly enabling,” lead author G. Allan Johnson (opens in new tab), a distinguished professor of radiology at Duke University, said in a statement (opens in new tab). “We can start looking at neurodegenerative diseases in an entirely different way.”

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For four decades, Johnson, with the help of a revolving team of students and researchers from Duke University’s Center for In Vivo Microscopy, has been working on improving MRI, which was invented by American physician Dr. Raymond Damadian (opens in new tab) 50 years ago.

MRI uses powerful magnets to generate magnetic fields, which cause the hydrogen atoms within water molecules in the body to align their “spins,” or point in a specific direction. The machine then uses a pulse of radio waves to “flip” the atoms’ spins. The atoms then fall back into alignment, and each flip generates a radio signal that can be detected by the MRI scanner and used to make an image.

To improve upon this technology, researchers created a souped-up MRI outfitted with a high-powered 9.4-tesla magnet. (For comparison, most MRIs are equipped with a 1.5- to 3-tesla magnet.) They also added gradient coils that are 100 times stronger than current models and are what create the images, as well as a high-speed computer that is as powerful as approximately 800 laptops, according to the statement.

After scanning the mouse brain, the researchers sent tissue samples to be imaged using a technique called light sheet microscopy, which allowed them to label specific groups of cells in the brain that were then mapped onto the original MRI. These additional steps provided a colorful view of cells and circuits throughout the brain, according to the statement.

The researchers took one set of MRI images that captured how the mouse’s brain-wide connectivity evolved with age. A second group of images showcased brilliantly colored brain connections that highlighted the deterioration of neural networks in a rodent model of Alzheimer’s disease, according to the statement.

By studying mouse models of human diseases like Alzheimer’s, researchers can better understand how these conditions emerge and progress in humans. The technique could also be useful for studying how the brain changes when mice are put on specific diets or given drugs in an effort to extend their life spans, Johnson said in the statement.

“The question is, is their brain still intact during this extended lifespan?” he said. “We have the capacity now to look at it. And as we do so, we can translate that directly into the human condition.”

 

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Giant prehistoric salmon had tusk-like teeth for defence, building nests

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The artwork and publicity materials showcasing a giant salmon that lived five million years ago were ready to go to promote a new exhibit, when the discovery of two fossilized skulls immediately changed what researchers knew about the fish.

Initial fossil discoveries of the 2.7-metre-long salmon in Oregon in the 1970s were incomplete and had led researchers to mistakenly suggest the fish had fang-like teeth.

It was dubbed the “sabre-toothed salmon” and became a kind of mascot for the Museum of Natural and Cultural History at the University of Oregon, says researcher Edward Davis.

But then came discovery of two skulls in 2014.

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Davis, a member of the team that found the skulls, says it wasn’t until they got back to the lab that he realized the significance of the discovery that has led to the renaming of the fish in a new, peer-reviewed study.

“There were these two skulls staring at me with sideways teeth,” says Davis, an associate professor in the department of earth sciences at the university.

In that position, the tusk-like teeth could not have been used for biting, he says.

“That was definitely a surprising moment,” says Davis, who serves as director of the Condon Fossil Collection at the university’s Museum of Natural and Cultural History.

“I realized that all of the artwork and all of the publicity materials and bumper stickers and buttons and T-shirts we had just made two months prior, for the new exhibit, were all out of date,” he says with a laugh.

Davis is co-author of the new study in the journal PLOS One, which renames the giant fish the “spike-toothed salmon.”

It says the salmon used the tusk-like spikes for building nests to spawn, and as defence mechanisms against predators and other salmon.

The salmon lived about five million years ago at a time when Earth was transitioning from warmer to relatively cooler conditions, Davis says.

It’s hard to know exactly why the relatives of today’s sockeye went extinct, but Davis says the cooler conditions would have affected the productivity of the Pacific Ocean and the amount of rain feeding rivers that served as their spawning areas.

Another co-author, Brian Sidlauskas, says a fish the size of the spike-toothed salmon must have been targeted by predators such as killer whales or sharks.

“I like to think … it’s almost like a sledgehammer, these salmon swinging their head back and forth in order to fend off things that might want to feast on them,” he says.

Sidlauskas says analysis by the lead author of the paper, Kerin Claeson, found both male and female salmon had the “multi-functional” spike-tooth feature.

“That’s part of our reason for hypothesizing that this tooth is multi-functional … It could easily be for digging out nests,” he says.

“Think about how big the (nest) would have to be for an animal of this size, and then carving it out in what’s probably pretty shallow water; and so having an extra digging tool attached to your head could be really useful.”

Sidlauskas says the giant salmon help researchers understand the boundaries of what’s possible with the evolution of salmon, but they also capture the human imagination and a sense of wonder about what’s possible on Earth.

“I think it helps us value a little more what we do still have, or I hope that it does. That animal is no longer with us, but it is a product of the same biosphere that sustains us.”

This report by The Canadian Press was first published April 24, 2024.

Brenna Owen, The Canadian Press

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Giant prehistoric salmon had tusk-like spikes used for defence, building nests: study

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A new paper says a giant salmon that lived five million years ago in the coastal waters of the Pacific Northwest used tusk-like spikes as defense mechanisms and for building nests to spawn.

The initial fossil discoveries of the 2.7-metre-long salmon in Oregon in the 1970s were incomplete and led researchers to suggest the fish had fang-like teeth.

The now-extinct fish was dubbed the “saber-tooth salmon,” but the study published in the peer-reviewed journal PLOS One today renames it the “spike-toothed salmon” and says both males and females possessed the “multifunctional” feature.

Study co-author Edward Davis says the revelation about the tusk-like teeth came after the discovery of fossilized skulls at a site in Oregon in 2014.

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Davis, an associate professor in the department of earth sciences at the University of Oregon, says he was surprised to see the skulls had “sideways teeth.”

Contrary to the belief since the 1970s, he says the teeth couldn’t have been used for any kind of biting.

“That was definitely a surprising moment,” Davis says of the fossil discovery in 2014. “I realized that all of the artwork and all of the publicity materials … we had just made two months prior, for the new exhibit, were all out of date.”

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SpaceX sends 23 Starlink satellites into low-Earth orbit

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April 23 (UPI) — SpaceX launched 23 Starlink satellites into low-Earth orbit Tuesday evening from Space Launch Complex 40 at Cape Canaveral Space Force Station in Florida.

Liftoff occurred at 6:17 EDT with a SpaceX Falcon 9 rocket sending the payload of 23 Starlink satellites into orbit.

The Falcon 9 rocket’s first-stage booster landed on an autonomous drone ship in the Atlantic Ocean after separating from the rocket’s second stage and its payload.

The entire mission was scheduled to take about an hour and 5 minutes to complete from launch to satellite deployment.

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The mission was the ninth flight for the first-stage booster that previously completed five Starlink satellite-deployment missions and three other missions.

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