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Your Brain’s Memory Capacity May Be as Big as the World Wide Web

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In an attempt to understand and measure the brain’s synapses, whose shape and size have remained mysterious to scientists, researchers at the University of Texas, Austin and the Salk Institute worked together to determine that the brain’s memory capacity is much larger than previously understood. The results, published in the journal eLife, estimate that an individual human brain may store as much as a petabyte of information—perhaps 10 times more than previously estimated, and about the equivalent of the World Wide Web.

The study was the first attempt “to reconstruct in three dimensions every single synapse and associated structure in a brain region,” to try to understand “basic synaptic structure and local connectivity among neurons,” Kristen Harris, co-senior author of the study and professor of neuroscience at UT Austin, tells mental_floss.

Synapses communicate signals between neurons. They're formed when the cable-like axon from one neuron connects with a "spine" on a dendrite, a branch-like structure extending from the neural cell body, of another. To better understand the way synaptic storage is measured, consider that a computer’s memory is measured in bits, each of which can have a value of 0 or 1. "In the brain, information is stored in the form of synaptic strength, a measure of how strongly activity in one neuron influences another neuron to which it is connected,” write the authors. “The number of different strengths can be measured in bits. The total storage capacity of the brain therefore depends on both the number of synapses and the number of distinguishable synaptic strengths."

Researchers were able to see these synapses by analyzing thin slices of tissue from the hippocampus—the brain region connected to learning and memory—from three male adult rats using electron microscopy. Then, over several years, they used computer software to reconstruct in 3D every “structural process” and roughly 500 synapses found in a tiny section of brain tissue the size of a single red blood cell.

They identified places where two neurons were connected to each other through two synapses, called "axon-coupled pairs,” which allowed them to estimate new sizes of synapses. What they found were 26 different “bins” of synapses that can store 4.7 bits of information each.

Not only is the diversity of synapses they observed in such a small brain region surprising, the storage capacity of each is “markedly higher than previous suggestions,” write the authors. Prior to this, researchers believed an individual synapse was only capable of storing 1 to 2 bits of information. This suggests we may have underestimated the memory capacity of the brain, which has trillions of synapses, "by an order of magnitude."

According to lead author Terry Sejnowski, in whose lab the study was conducted, "Our new measurements of the brain’s memory capacity increase conservative estimates by a factor of 10 to at least a petabyte, in the same ballpark as the World Wide Web." 

The research provides researchers who study memory and learning with a deeper understanding of the brain’s memory capacity, and a new dataset to work with. “This is just the beginning—a tiny chink in the mysterious armor of the structure and function of synapses in the brain,” Harris says.

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More Details Emerge About 'Oumuamua, Earth's First-Recorded Interstellar Visitor
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In October, scientists using the University of Hawaii's Pan-STARRS 1 telescope sighted something extraordinary: Earth's first confirmed interstellar visitor. Originally called A/2017 U1, the once-mysterious object has a new name—'Oumuamua, according to Scientific American—and researchers continue to learn more about its physical properties. Now, a team from the University of Hawaii's Institute of Astronomy has published a detailed report of what they know so far in Nature.

Fittingly, "'Oumuamua" is Hawaiian for "a messenger from afar arriving first." 'Oumuamua's astronomical designation is 1I/2017 U1. The "I" in 1I/2017 stands for "interstellar." Until now, objects similar to 'Oumuamua were always given "C" and "A" names, which stand for either comet or asteroid. New observations have researchers concluding that 'Oumuamua is unusual for more than its far-flung origins.

It's a cigar-shaped object 10 times longer than it is wide, stretching to a half-mile long. It's also reddish in color, and is similar in some ways to some asteroids in our solar system, the BBC reports. But it's much faster, zipping through our system, and has a totally different orbit from any of those objects.

After initial indecision about whether the object was a comet or an asteroid, the researchers now believe it's an asteroid. Long ago, it might have hurtled from an unknown star system into our own.

'Oumuamua may provide astronomers with new insights into how stars and planets form. The 750,000 asteroids we know of are leftovers from the formation of our solar system, trapped by the Sun's gravity. But what if, billions of years ago, other objects escaped? 'Oumuamua shows us that it's possible; perhaps there are bits and pieces from the early years of our solar system currently visiting other stars.

The researchers say it's surprising that 'Oumuamua is an asteroid instead of a comet, given that in the Oort Cloud—an icy bubble of debris thought to surround our solar system—comets are predicted to outnumber asteroids 200 to 1 and perhaps even as high as 10,000 to 1. If our own solar system is any indication, it's more likely that a comet would take off before an asteroid would.

So where did 'Oumuamua come from? That's still unknown. It's possible it could've been bumped into our realm by a close encounter with a planet—either a smaller, nearby one, or a larger, farther one. If that's the case, the planet remains to be discovered. They believe it's more likely that 'Oumuamua was ejected from a young stellar system, location unknown. And yet, they write, "the possibility that 'Oumuamua has been orbiting the galaxy for billions of years cannot be ruled out."

As for where it's headed, The Atlantic's Marina Koren notes, "It will pass the orbit of Jupiter next May, then Neptune in 2022, and Pluto in 2024. By 2025, it will coast beyond the outer edge of the Kuiper Belt, a field of icy and rocky objects."

Last month, University of Wisconsin–Madison astronomer Ralf Kotulla and scientists from UCLA and the National Optical Astronomy Observatory (NOAO) used the WIYN Telescope on Kitt Peak, Arizona, to take some of the first pictures of 'Oumuamua. You can check them out below.

Images of an interloper from beyond the solar system — an asteroid or a comet — were captured on Oct. 27 by the 3.5-meter WIYN Telescope on Kitt Peak, Ariz.
Images of 'Oumuamua—an asteroid or a comet—were captured on October 27.
WIYN OBSERVATORY/RALF KOTULLA

U1 spotted whizzing through the Solar System in images taken with the WIYN telescope. The faint streaks are background stars. The green circles highlight the position of U1 in each image. In these images U1 is about 10 million times fainter than the faint
The green circles highlight the position of U1 in each image against faint streaks of background stars. In these images, U1 is about 10 million times fainter than the faintest visible stars.
R. Kotulla (University of Wisconsin) & WIYN/NOAO/AURA/NSF

Color image of U1, compiled from observations taken through filters centered at 4750A, 6250A, and 7500A.
Color image of U1.
R. Kotulla (University of Wisconsin) & WIYN/NOAO/AURA/NSF

Editor's note: This story has been updated.

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Scientists Analyze the Moods of 90,000 Songs Based on Music and Lyrics
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Based on the first few seconds of a song, the part before the vocalist starts singing, you can judge whether the lyrics are more likely to detail a night of partying or a devastating breakup. The fact that musical structures can evoke certain emotions just as strongly as words can isn't a secret. But scientists now have a better idea of which language gets paired with which chords, according to their paper published in Royal Society Open Science.

For their study, researchers from Indiana University downloaded 90,000 songs from Ultimate Guitar, a site that allows users to upload the lyrics and chords from popular songs for musicians to reference. Next, they pulled data from labMT, which crowd-sources the emotional valence (positive and negative connotations) of words. They referred to the music recognition site Gracenote to determine where and when each song was produced.

Their new method for analyzing the relationship between music and lyrics confirmed long-held knowledge: that minor chords are associated with sad feelings and major chords with happy ones. Words with a negative valence, like "pain," "die," and "lost," are all more likely to fall on the minor side of the spectrum.

But outside of major chords, the researchers found that high-valence words tend to show up in a surprising place: seventh chords. These chords contain four notes at a time and can be played in both the major and minor keys. The lyrics associated with these chords are positive all around, but their mood varies slightly depending on the type of seventh. Dominant seventh chords, for example, are often paired with terms of endearment, like "baby", or "sweet." With minor seventh chords, the words "life" and "god" are overrepresented.

Using their data, the researchers also looked at how lyric and chord valence differs between genres, regions, and eras. Sixties rock ranks highest in terms of positivity while punk and metal occupy the bottom slots. As for geography, Scandinavia (think Norwegian death metal) produces the dreariest music while songs from Asia (like K-Pop) are the happiest. So if you're looking for a song to boost your mood, we suggest digging up some Asian rock music from the 1960s, and make sure it's heavy on the seventh chords.

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