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The Incredible Shrinking Human Brain

Michael Balter
Science Now
Mon, 25 Jul 2011 15:00 UTC
Shrinking Brain
© (woman) Fotostock; (chimp) Danita Delimont/AlamyDownhill slope. Humans and chimps live relatively long lives, but only the human brain seems to degenerate over time.

The human brain is big, and it's powerful, able to dream up innovative solutions to complex problems. Yet our brains don't age well: As we grow older, they tend to shrink and become increasingly vulnerable to cognitive dysfunctions such as memory loss and dementia. A new magnetic resonance imaging (MRI) study comparing humans and chimpanzees finds that chimp brains maintain their size as they age. Slowly losing our minds, it turns out, may be the evolutionary price we pay for having bigger brains and longer life spans.

As far as researchers can tell, humans are the only animals subject to specific brain maladies such as Alzheimer's disease, which in the United States afflicts nearly 50% of people over the age of 85. But even normal, apparently healthy human brains show the effects of aging, such as the buildup of amyloid-β plaque deposits and loss of neural connections, especially in regions linked to learning and memory. And previous studies of human brains have suggested that these brain regions, which include the frontal lobe and the hippocampus, are especially prone to shrinkage with age.

Although few similar studies of other primates have been conducted, recent research with rhesus monkeys has shown only very limited shrinkage with age. Nevertheless, the evolutionary lineages leading to humans and rhesus monkeys diverged about 30 million years ago, leaving scientists in the dark about when the human pattern of brain aging might have begun.
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Question

Are We Alone In the Universe? New Analysis Says Maybe

Natalie Wolchover
Live Science
Mon, 25 Jul 2011 17:05 UTC
Alien Life
© Discovery Channel / Evergreen FilmsStill from the 2005 film Alien Planet.

Scientists engaged in the search for extraterrestrial intelligence (SETI) work under the assumption that there is, in fact, intelligent life out there to be found. A new analysis may crush their optimism.

To calculate the likelihood that they'll make radio contact with extraterrestrials, SETI scientists use what's known as the Drake Equation. Formulated in the 1960s by Frank Drake of the SETI Institute in California, it approximates the number of radio-transmitting civilizations in our galaxy at any one time by multiplying a string of factors: the number of stars, the fraction that have planets, the fraction of those that are habitable, the probability of life arising on such planets, its likelihood of becoming intelligent and so on.

The values of almost all these factors are highly speculative. Nonetheless, Drake and others have plugged in their best guesses, and estimate that there are about 10,000 tech-savvy civilizations in the galaxy currently sending signals our way - a number that has led some scientists to predict that we'll detect alien signals within two decades.
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Magnify

Retinal Cells Thoughts to be the Same Are Not: Study


MedicalXpress
Mon, 25 Jul 2011 14:40 UTC
The old adage "Looks can be deceiving" certainly rings true when it comes to people. But it is also accurate when describing special light-sensing cells in the eye, according to a Johns Hopkins University biologist.

In a study recently published in Nature, a team led by Samer Hattar of the Department of Biology at the Krieger School of Arts and Sciences and Tudor Badea at the National Eye Institute found that these cells, which were thought to be identical and responsible for both setting the body's circadian rhythm and the pupil's reaction to light and darkness, are actually two different cells, each responsible for one of those tasks.

"In biology, as in life, you can't always trust what you see," said Hattar. "You have to delve deep to find out what's really going on. This study has shown that two structurally similar neurons are actually quite different and distinct, communicate with different regions of the brain and influence different visual functions."

The findings are significant, Hattar said, because doctors sometimes use pupillary light reflex (the pupil's response to light and darkness) as a way of diagnosing patients who may have sleep problems, and those clinicians now must recognize that the cells controlling pupillary response and those controlling the sleep-wake cycle are different.
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Bizarro Earth

NASA to Land Astronauts Where No Man Has Gone Before - Asteroids


gulfnews.com
Mon, 25 Jul 2011 00:00 UTC
Image
© AP PhotoThe asteroid Vesta shot from a distance of about 15,000km by the Dawn spacecraft on July 17. If all goes to plan at NASA, there could be a man on one such astral body by 2025.
And with no Scotty to beam them up, allocated 15-year time looks daunting

Houston: With the space shuttle now history, NASA's next great mission is so audacious, the agency's best minds are wrestling with how to pull it off: Send astronauts to an asteroid in less than 15 years.

The challenges are innumerable. Some old-timers are grousing about it, saying going back to the moon makes more sense. But many NASA brains are thrilled to have such an improbable assignment. And NASA leaders say civilization may depend on it.

An asteroid is a giant space rock that orbits the sun, like Earth. And someday one might threaten the planet.

But sending people to one won't be easy. You can't land on an asteroid because you'd bounce off - it has virtually no gravity. Reaching it might require a NASA spacecraft to harpoon it. Heck, astronauts couldn't even walk on it because they'd float away.
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Magic Wand

Myelin Influences How Brain Cells Send Signals


The Ohio State University
Thu, 21 Jul 2011 08:24 UTC
Image
© The Ohio State UniversityChen Gu
The development of a new cell-culture system that mimics how specific nerve cell fibers in the brain become coated with protective myelin opens up new avenues of research about multiple sclerosis. Initial findings suggest that myelin regulates a key protein involved in sending long-distance signals.

Multiple sclerosis (MS) is an autoimmune disease characterized by damage to the myelin sheath surrounding nerve fibers. The cause remains unknown, and it is a chronic illness affecting the central nervous system that has no cure.

MS has long been considered a disease of white matter, a reference to the white-colored bundles of myelin-coated axons that project from the main body of a brain cell. But researchers have discovered that the condition also affects myelinated axons scattered in gray matter that contains main bodies of brain cells, and specifically the hippocampus region, which is important for learning and memory.
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Sherlock

Hotspot found on Moon's far side

Stuart Gary
ABC
Mon, 25 Jul 2011 12:29 UTC
Image
© NASA/JPLUntil now the best known examples of volcanism were on the Moon's near side
Scientists have found evidence of volcanoes on the far side of the Moon.

The new discovery, reported in the journal Nature Geoscience is a rare example of volcanism on the lunar surface not associated with asteroid, meteor or comet impact events.

Until now the best known examples of volcanism were on the Moon's near side in a region known as the Procellarum KREEP terrane.

A team of scientists, led by Dr Bradley Jolliff from Washington University in St Louis, used images and other data gathered by NASA's Lunar Reconnaissance Orbiter (LRO) to assess the composition of an unusual region on the far side of the moon called the Compton-Belkovich thorium anomaly.
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Beaker

With DNA Discovery, 'Human Soup' Gets More Complex


Fox News
Fri, 22 Jul 2011 00:00 UTC
DNA
© unknownAn illustration of the double-helix structure of a strand of DNA.
The human recipe just got complicated: It turns out there are more ingredients in us than we thought.

In high school science, we were taught of the four basic units that make up DNA -- adenine, guanine, thymine and cytosine. When scientists talk of DNA sequencing, it's written as strings of these units: ATCGGTGA, and so on.

In recent years, scientists expanded that list of nucleotides from four to six. And in a study published online in the most recent issue of Science magazine, researchers from the University of North Carolina School's medical school have discovered the seventh and eight bases of DNA.

But the meaning of this extra ingredient in the alphabet soup that makes us who we are isn't as simple as A, B, C.

"Before we can grasp the magnitude of this discovery, we have to figure out the function of these new bases," said Yi Zhang, biochemistry and biophysics professor at UNC.'s Howard Hughes Medical Institute.
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Bizarro Earth

Paleoecologists Suggest Mass Extinction Due to Huge Methane Release

Bob Yirka
PhysOrg.com
Fri, 22 Jul 2011 15:00 UTC
earth
© PhysOrg.comThis wide angle view of the Earth is centered on the Atlantic Ocean between South America and Africa.
Micha Ruhl and colleagues from the University of Copenhagen's Nordic Center for Earth Evolution have published a paper in Science where they contend that the mass extinction that occurred at the end of the Triassic period, was due to a "sudden" increase in the amount of methane in the atmosphere due to the effects of global warning that resulted from the spewing of carbon dioxide from volcanoes.

Prior to this research, most scientists have believed that the sudden extinction of nearly half of all life forms on the planet was due solely to the emissions from that were occurring in what was to become the Atlantic Ocean. Ruhl et al contend that instead, what happened, was that the small amount of atmospheric heating that occurred due to the exhaust from the volcanoes, caused the oceans to warm as well, leading to the melting of ice crystals at the bottom of the sea that were holding on to methane created by the millions of years of decomposing . When the ice crystals melted, methane was released, which in turn caused the planet to warm even more, which led to more methane release in a , that Ruhl says, was the real reason for the that led to the next phase in world history, the rise of dinosaurs.
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Info

Time Travel Impossible, Say Scientists


Agence France-Presse
Sun, 24 Jul 2011 13:30 UTC
Time Travel
© iStockPhotoBy proving a single photon can't travel faster than light, scientists say they have proven time travel is impossible.
Hong Kong physicists say they have proved that a single photon obeys Einstein's theory that nothing can travel faster than the speed of light -- demonstrating that outside science fiction, time travel is impossible.

The Hong Kong University of Science and Technology research team led by Du Shengwang said they had proved that a single photon, or unit of light, "obeys the traffic law of the universe."

"Einstein claimed that the speed of light was the traffic law of the universe or in simple language, nothing can travel faster than light," the university said on its website.

"Professor Du's study demonstrates that a single photon, the fundamental quanta of light, also obeys the traffic law of the universe just like classical EM (electromagnetic) waves."
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Magic Wand

Gardening in the brain: Specialist cells prune connections between neurons


European Molecular Biology Laboratory
Thu, 21 Jul 2011 02:24 UTC
Image
© EMBL/R.PaolicelliThis is microglia (green) in a mouse brain. The nuclei of all cells in the brain are labeled blue
Gardeners know that some trees require regular pruning: some of their branches have to be cut so that others can grow stronger. The same is true of the developing brain: cells called microglia prune the connections between neurons, shaping how the brain is wired, scientists at the European Molecular Biology Laboratory (EMBL) in Monterotondo, Italy, discovered. Published online today in Science, the findings could one day help understand neurodevelopmental disorders like autism.

"We're very excited, because our data shows microglia are critical to get the connectivity right in the brain," says Cornelius Gross, who led the work: "they 'eat up' synapses to make space for the most effective contacts between neurons to grow strong."
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