Hey boy, you really activate my ventral midbrain.

By Brooke Napier

Scientists at CalTech simultaneously found a way to stimulate your midbrain without invasive methods (ie: opening up your skull) and make you find them attractive.

Chib, et al. reported in Translational Psychiatry that by using their newly designed noninvasive method called transcranial direct current stimulation (tDCS) on the prefrontal cortex they were able to activate the interconnected midbrain.

Why would you want to activate the midbrain?

The ventral midbrain (also known as: the substantia nigra and ventral tegmental area) is the location of a group of very important dopaminergic neurons (neurons whose primary neurotransmitter is dopamine).  These dopaminergic neurons are involved in reward, addiction, movement, cognition, motivation, intense emotions like love, and many more things. TL;DR – they’re important.

The neurons project into multiple areas of the brain and impairments in these neurons have been associated with a number of neurological and neuropsychiatic disorders such as Parkinson’s disease, depression, and addiction.

When impairment occurs the most popular means of influencing these impaired neurons is through pharmacological intervention or deep brain stimulation. Pharmacological intervention will not be region-specific, and will influence the dopamine levels throughout not only the nervous system, but also other systems including the immune system, the pancreas, etc.

And, well, deep brain stimulation is Deep. Brain. Stimulation… wherein neurosurgeons drill a hole into your skull and implant a device that is essentially a brain pacemaker. This device will send electrical impulses to where ever the electrode is placed. Though it sounds medieval, this treatment has been successful in treating symptoms of Parkinson’s disease, depression, dystonia, etc.

Adapted from: http://www.mayfieldclinic.com/Images/PE-DBS_fig1.jpg

Previously (meaning before this study), the only means of non-invasive stimulation of the brain was through methods that could only stimulate neurons on the cortical surface, not anywhere near the ventral midbrain.

One of these methods is called transcranial direct current stimulation, which has been shown to be able to influence midbrain neurons by stimulation of the frontal cortex.

What is transcranial direct current stimulation (tDCS)?

tDCS applys  a small current between anodal and cathodal electrodes placed on the scalp, in this case they would be placing the electrodes on the prefrontal cortex in effort to induce activation of dopaminergic neurons in the ventral midbrain.

Adapted from: (http://www.transcranialbrainstimulation.com/images/home-page-slides/tdcs-patient.jpg)

Is this where the good-looking people come in?

Well, they needed a read-out. Turns out the ventral midbrain is also important in determining attractiveness of other people.

Here’s the set up: The experiment was divided into three sessions. The first session (before stimulation) participants made “facial attractiveness judgements”, during the second session participants were stimulated via tDCS for 15 mins, and during the final session (after stimulation) participants again made facial attractiveness judgments.

There were three experimental groups, the main condition which was the group that received the tDCS treatment (anodal stimulation of the ventromedial prefrontal cortex and cathodal stimulation from the right dorsolateral prefrontal cortex), the sham group that received no stimulation, and the active sham group that received stimulation with the anode and cathode switched.

As the graph depicts, the group that received the tDCS treatment perceived a higher attractiveness level after stimulation. Though the attractiveness level was a great read-out, they also quantified this behavior by measuring activation with functional magnetic resonance imaging (fMRI). fMRI scans show that tDCS treatment induced a larger effect size and that increased with perceived attractiveness levels.

This was the very first time that anyone has shown tDCS directly yields both stimulation-induced changes in the brain connectivity AND corresponding behavioral changes – which makes the future bright for using tDCS in the clinic for treating Parkinson’s disease and psychiatric disorders.

Basically, all of the researchers got a wicked paper and a hot date out of this study.

Chib VS, Yun K, Takahashi H, & Shimojo S (2013). Noninvasive remote activation of the ventral midbrain by transcranial direct current stimulation of prefrontal cortex. Translational psychiatry, 3 PMID: 23756377

How far away is that pulsar, exactly?

A team of scientists just used a Hemisphere-sized network of radio telescopes to find out exactly (well, within 0.4%) how far away the binary pulsar J2222-0137 is. With this new distance, which is 15% closer than everybody thought it was, astronomers can figure out what the pulsar's orbiting companion is and are one step closer to detecting gravitational waves.

Spoiler alert: This pulsar is 871.4 light-years from Earth.

But it's not the actual distance that matters. The important part is that astronomers can figure out the distance at all. Here's the story in three acts.

Act 1: PulsarsThis is not an image (Credit: Bill Saxton/NRAO/AUI).

They're weird.

Aside from black holes, they're the weirdest things in the universe. They have more mass than the Sun but are the sizes of earthly cities. In other words, dense. According to a Nature Physics result released today, they are made of nuclear pasta. They spin tens or hundreds of times every second (seriously, imagine DC rotating 716 times in a "one Mississippi," as the fastest known pulsar does) and warp spacetime way more than you do. Once every time they spin, the radiation coming out of their poles is pointed toward Earth, so we see a pulse.

Most pulsars are precise "clocks," hardly slowing down at all. If a pulsar is spinning once per second today, you can bet the farm that it will be spinning once per second tomorrow. As long as the person you're betting against doesn't have a super-atomic stopwatch. The average pulsar will slow down by approximately 10^-15 seconds every second, which means that a pulsar that spins every 1 second today will spin once every 0.999999999136 seconds tomorrow. 

But the fast-spinning pulsars -- called millisecond pulsars (MSPs) -- are even more precise. If one rotated every 0.01 second, that number might change to 0.00999999999999136 seconds tomorrow.

These minute changes in period, too, are stable.

Act 2: Pulsars as tools

Because pulsars appear to pulse once for each rotation AND their rotation changes so slowly and measurably, astronomers know when they should see each pulse.

For the fastest and most stable objects, one could almost say they know exactly when they should see each pulse. So when one is off by 0.0000001 second, a dozing graduate student (j/k) sits up and takes notice.Bow down, atomic clocks. You have been beaten. By tiny, dead stars. (Credit: METAS).

Astronomers who are part of the European Pulsar Timing Array (EPTA), the Parkes Pulsar Timing Array (PPTA), and North American Nanohertz Observatory for Gravitational Waves (NANOGrav) are searching for -- you guessed it -- gravitational waves (GWs).

GWs ripple spacetime when objects with mass interact, like when they orbit each other or collide. As a GW passes through the universe, undulating the fabric of the cosmos, it will affect pulsars' pulses. Astronomers, obsessively monitoring a batch of the most reliable pulsars, are watching for tiny deviations in their pulses' arrival times, incidcating they were delayed by GWs. The set of pulsars -- currently there are 40 -pulsars that are worthy -- that astronomers watch closely is called a "pulsar timing array." Having more pulsars and knowing more about each one -- say, its distance from Earth -- increases the array's abilities.

Although scientists have found indirect evidence that gravitational waves are real and not something Einstein just made up, no one has seen them directly. Pulsar-timing astronomers would like to be the first. 

Act 3: Binary pulsar J222-0137

In the research paper headed-up by A. T. Deller of ASTRON, the scientists share new details about J222-0137, which is in a binary system that the Green Bank Telescope (GBT) discovered as part of a large survey.

Objects orbiting around each other radiate gravitational waves into space. They don't look like this unless you squint and turn your head to the right (Credit: NASA).

It

• is 871.4 light-years away
• spins every 32.82 milliseconds, or 30.5 times every second
• will spin 0.00000000000000409536 seconds slower tomorrow
• has a binary companion that is at least 1.1 times as massive as the Sun. Its nature is still unknown, but since astronomers know its mass and its distance, ID is on the way. If it shows up in optical observations, it's likely a white dwarf. If not, it's likely a fraternal twin neutron star.

They did all of this with precise observations from the National Radio Astronomy Observatory's Very Long Baseline Array, a set of 10 radio telescopes that work together to synthesize a larger radio telescope that has higher resolution than Hubble. By measuring the pulsar's parallax*, or how much it appears to move relative to distant background objects, they made the most accurate distance measurement ever for this kind of object.

Gathering up lots of accurate distance measurements to the timing-array pulsars would help in the race to finally "see" gravitational waves. Unfortunately, the paper says, most of the superfast pulsars are much farther away than J222-0137, and their parallaxes would be harder -- or, for the most part, impossible -- to measure well.

But fear not. Science, like love, will find a way ... to find gravitational waves.

It will, however, take a lot longer if the National Science Foundation (NSF) de-funds both the telescope that discovered this pulsar (and at least 85 of its closest pulsar friends) -- the GBT --- and the VLBA. Both are under threat of divestment, meaning all NSF funding would disappear.

Not good for many science topics, but especially for GW research. Maura McLaughlin, a professor at West Virginia University and an author on this paper, says, "Both the GBT and the VLBA are absolutely essential to detecting gravitational waves with pulsars. The GBT is the most sensitive instrument in the world for pulsar searches, and the VLBA can measure pulsar distances more accurately than any other telescope. Accurate distances to pulsars dramatically increase our ability to characterize gravitational wave sources. The GBT and the VLBA are really a perfect match, and it would be disastrous if we lost one or, god forbid, both of them."

Deller, A., Boyles, J., Lorimer, D., Kaspi, V., McLaughlin, M., Ransom, S., Stairs, I., & Stovall, K. (2013). VLBI ASTROMETRY OF PSR J2222-0137: A PULSAR DISTANCE MEASURED TO 0.4% ACCURACY The Astrophysical Journal, 770 (2) DOI: 10.1088/0004-637X/770/2/145

**I've written about parallax several times. If you're interested in this technique's superpowers, consider these posts:

1. For a summary of why parallax is important, see "Wink once if you think astronomy is is better because of parallax."
2. VLBA-observed parallax bested Hubble's distance estimates and solved a mystery.
3. Parallax also proved the most famous black hole actually is a black hole and not something else weird.
4. To read an overview of the different ways scientists determine how far away stuff in space is, check out the intro of "Variable Stars: Blinking the way to better distances since 1957."

A new microbe that correlates with weight loss

by Brooke Napier

Meet the bacterium Akkermansia muciniphila. It’s new to me too. I’m scared but excited.

All I remember about Belgium is the chocolate waffles, sweet beautiful waffles.

Patrice Cani and her team at the Walloon Excellence in Life sciences and BIOtechnology (WELBIO) Institute in Belgium isolated Akkermansia muciniphila from the mucus layer of the intestine. They were particularly interested in this mucus dwelling bacterium because they found the presence of it interferes with the permeability of the intestinal layer.

Why is the permeability of the intestinal layer important?

Recently this same group found that increased permeability of the intestinal layer is associated with obesity and type 2 diabetes. They found this by showing that obese patients or patients diagnosed with type 2 diabetes showed signs of bacterial lipids (specifically endotoxin lipopolysaccharide) within the blood.

How would bacterial lipids get into the blood? Permeability of the intestinal wall.

The presence of these bacterial lipids cause chronic inflammation of the intestine, which is horrible for anyone to live with (but comes in handy when you know this type of person because they always know where the bathroom is…) and this inflammation is a hallmark of obesity and type 2 diabetes.

See that circle? It’s a beautiful scientific circle, but it’s a dreadful real-life circle. What is missing is what is causing the intestinal permeability, and that is where Akkermansia mucinphila comes in…

This is not the first group to have the idea that our gut microbiota is responsible for intestinal permeability in this scheme, however they are the first to identify one out of millions of bacterial species that correlates with this symptom, and that’s pretty huge.

Akkermansia mucinphila is a mucin-degrading bacterium that resides in the mucus layer of the intestine. It loves the mucus layer so much that is the predominate species found in this wet, sticky, dark layer – and interestingly the presence of this bacterium inversely correlates with body weight in humans (and mice!). Meaning, genetically and diet-induced obese mice had a dramatic decrease in A. mucinphila.

How is Akkermansia mucinphila related to weight loss/gain and type 2 diabetes?

It turns out, the presence of A. mucinphila in the intestines restores intestinal permeability in diet-induced obese mice, or type 2 diabetic mice. They did this by having control mice, high-fat diet mice, and another set of control + A. mucinphila (Akk) and high-fat diet + mucinphila (below).

M = mucus layer, IM = inner mucus layer

Basically, A. mucinphila decreased intestinal permeability, bacterial lipids in the blood, insulin resistance, and chronic inflammation AND increased mucus layer thickness (above) and adipose tissue (FAT!) degradation – all in obese or type 2 diabetes model mice. All of this without changing any of the other gut microbiota.

Miracle bug? Perhaps.

Basically I want this bug in me. Interestingly, there is a prebiotic that increases colonization of the gut with A. mucinphila called oligofructose, however the mechanism is uses to increase this gut microbe is unknown (along with it’s side effects in humans). So maybe just a pill with A. mucinphila within a capsule (that can withstand the low pH of the stomach)?  Would that even work? I’m not sure, but…

I would sign up for that study.

Everard, A., Belzer, C., Geurts, L., Ouwerkerk, J., Druart, C., Bindels, L., Guiot, Y., Derrien, M., Muccioli, G., Delzenne, N., de Vos, W., & Cani, P. (2013). Cross-talk between Akkermansia muciniphila and intestinal epithelium controls diet-induced obesity Proceedings of the National Academy of Sciences, 110 (22), 9066-9071 DOI: 10.1073/pnas.1219451110

SS Cygni: A red dwarf-white dwarf pair that's closer than scientists thought (or, how Hubble got told)

Determining distances to objects in space is no easy task, unless you're some kind of special person with an impossible faster-than-light spaceship and can just measure the miles between Earth and UDFj-39546284. This is what it's like to be in a helicopter above SS Cygni, minus the arrows and text (Credit: J. Miller-Jones [ICRAR], using software created by R. Hynes).But no astronomer I know has such a ship, and so they all are likely to say, "That galaxy is 3 billion light-years away, plus or minus a million light-years."

And that level of uncertainty doesn't apply only to far-away objects. It also applies to relatively nearby stars, such as SS Cygni, a close binary system in which a red dwarf and a white dwarf orbit each other every 6.6 hours. The Hubble Space Telescope had pegged the distance between us and SS Cygni at 540 light-years.

And, well, it's not often that you get to tell the Hubble Space Telescope it's wrong. But when the Hubble Space Telescope is wrong, you gotsta tell it loud and clear. So, "Hubble, SS Cygni is more like 372 light-years away. Take that in your face."

And what instruments were able to so diss the high-res space telescope? The Very Long Baseline Array (VLBA), a combination of 10 radio antennas spread between Hawaii and St. Croix, giving the telescope as a whole an effective diameter of more than 5,000 miles, and the European VLBI Network (EVN), which has antennas in Europe, China, Russia, and South Africa.

Here's the low-down on the SS Cygni system, how scientists used the VLBA to determine its distance from us, and why that 168 light-year revision matters.

What is this binary system like?

The solar flare in the upper left extends 100,000 miles from the Sun's surface, the same distance as the separate between SS Cygni's two stellar components.

Tight. The red and white dwarfs are separated by only 100,000ish miles. If the Sun were that close to another star, the star would begin just at the end of the solar flare in the image to the right.

Such a close sharing of quarters can lead to violent outbursts on the part of the white dwarf. The white dwarf roommate siphons material--Ramen noodles, the last of the Fruity Pebbles, clean underwear--from the red dwarf roommate, and all that stuff forms a disk around the white dwarf. When the white dwarf is taking a lot of material, the relationship is stable (and the analogy totally unravels), but when the transfer rate is lower, the disk destabilizes and undergoes an outburst. 

This burst happens with regularity--in the case of SS Cygni, once every 49ish days. Because of these explosions, it is categorized as a dwarf nova. It's only during the burst period that the system emits radio waves. 

But it didn't appear to work the same way all the other dwarf novae do.

This is what astronomers thought until today: SS Cygni is too bright. It's so bright that lots of mass must be changing hands. So much mass that the disk should always be stable. Meaning SS Cygni should never, ever have an outburst. But it does--often. If SS Cygni is in fact 500 light-years away, and is super bright but does the nova thing anyway, our theories about how dwarf novae work must be wrong.

So when amateur astronomers from the American Association of Variable Star Observers (AAVSO) noticed that it was, in fact, having an outburst, they informed professional astronomers, who perked up and took action because they were eager to prove that their theories were not, in fact, wrong.

When an object emits radio waves, and you have a 5,000-mile diameter radio telescope, you can do science. 

Who are these so called "professional astronomers," and what did they do with that gigantic telescope?

A team led by James Miller-Jones from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR) took advantage of the radio emission to watch how it "wobbled" compared to the galaxies behind it (from our perspective).

"The wobble we were detecting is the equivalent of trying to see someone stand up in New York from as far as away as Sydney," Miller-Jones said in a press release.

Why couldn't astronomers do that any old time using the optical light, even if it's not emitting radio waves?

After all, SS Cygni is always putting out visible light.

"Our key advantage was using radio telescopes to observe the system. In visible light, optical telescopes like Hubble see hundreds of different stars, all of which are moving by different amounts, whereas in radio waves the background we compare against is much further away and therefore doesn't appear to move at all," co-author Assistant Professor Gregory Sivakoff from the University of Alberta, said.

Energetic radio galaxies were much more common at the beginning of the universe, so most are extremely far away.

Why are far-off things better for determining distance?

Astronomers were trying to find SS Cygni's parallax, which is the numerical measurement of the "wobble"--how much it appears to move relative to a distant background when the observer's position changes.

When you're looking out the passenger window of a car, the road's shoulder is flying by you, but the mountain peak moves slowly across your view. If we can measure the angle by which an object appears to move due to our motion, we can determine how far away it is--this is parallax.Parallax is based on the concept that objects close to you seem to "move" faster when you're moving than far-away objects do. I'm about to plagiarize myself here, but I'm being honest about it. "When you're looking out the passenger window of a car, the road's shoulder is flying by you, but the mountain peak moves slowly across your view." Because of that differential, astronomers can measure the difference between how the "shoulder"and the "mountain peak" change relative to each other and thus determine how far away the "shoulder" is.

Wikipedia user Natejunk2004, aka Best Screen-Named Person Ever, made this animation demonstrating what I clumsily tried to convey above.

Miller-Jones, et al., looked at SS Cygni when Earth was at different, widely separated points in its orbit (see the figure to the left) and observed where it was relative to background radio galaxies from each of those perspectives. The radio galaxies, by the way, are so distant that they don't seem to move at all.

So they used parallax to figure out that SS Cygni is 168 light-years closer than they'd previously thought. So what?

Well, if SS Cygni is closer to us, it's not quite as intrinsically bright as scientists thought. It's just nearby (in the same way that the Sun seems to be really bright compared to Sirius but is really just average and next-door). Which means that the mass transfer rate is low enough to create an unstable disk. Which means that astronomers were right about dwarf novae (or, at least, that they weren't wrong in this particular way).

And we all know how astronomers love to be right. Right?

But, really, using evidence to prove that a physical process does mesh with a theory is truly a significant scientific feat. It is, in fact, what science is all about.

How to see a black hole birth

by Sarah Scoles

What if this was what you did to the space around you? How would you feel? Well, scientists can't answer that, but they now may be able to tell when a black hole is forming. even if its stellar progenitor doesn't explode (Credit: Alain Riazuelo, IAP/UPMC/CNRS).

When really massive stars die, they collapse into black holes. But no one has actually observed this process in action. So what happens, exactly, when a star stops being a star and starts being the universe's weirdest object? How does it look, and what signals would allow scientists to point at some tiny spot in the sky and say, "Hey, right there, a black hole was just born"?

A new paper suggests one such signal, and, almost as importantly, this paper has a great title: "Taking the 'Un' out of 'Unnovae.'" Good job, sole author theoretical astrophysics postdoctoral researcher Anthony L. Piro.

Piro suggests that the death of a star and the subsequent birth of a black hole--the Simba-style circle of cosmic life--is marked by a specific type of flash.

Wait, did you just use the word 'unnova' and proceed to write another sentence before defining it?

Sorry. While some stars-turning-black-holes produce spectacular explosions that are supernovae or supernova-like and/or include ultra-energetic gamma-ray bursts, others may simply implode and disappear without all the fanfare. This "now it's there, now it's not" version is the theoretical-and-as-yet-unobserved unnova. As in, not a nova.

But it is something, even if it is not a nova. When a massive star is turning into a black hole, it collapses into a neutron star first, its protons and electrons so squished together that they combine into neutrons. As the star is essentially cramming itself into a medium-sized city's limits, it is also releasing neutrinos--nearly massless particles that travel almost as fast as light and don't interact much with the rest of the universe. As a result, the star loses about a tenth of its mass in the course of a few seconds.

Consider losing a tenth of your mass. Like you would, the star feels its loss of gravitational strength. While you would probably just run faster or jump higher or be really hungry, the star can no longer hold on to its outer layers. As they expand, they create a shock wave in the star's envelope, which is consequently ejected. When the wave reaches the star's surface, the surface heats up and glows. It's a bit like a slow-mo, low-energy supernova...which is not a supernova at all and is, in fact, an unnova. The resulting light, though it would last for about a year, is too faint for our telescopes to reliably identify at the moment.

Piro's paper asks the question, "Is there a brighter signature within the unnova-ing process that scientists could latch onto?"

The short answer: Yes! A flash.

The longer answer: When the shock wave hits the star's surface, he predicts there will be a blast of light. Not nearly as bright as a supernova, but 10-100 (I know, I know, check out that range) times brighter than the "glow."

In other words, if scientists can find instances of this flash, which Piro estimates should occur detectably once per year, they will be able to say, "Look at that unnova! Probably," and will suspect that they have seen a black hole being born. And who doesn't want to be in the delivery room to witness that?

All of a sudden, this emerges from the dying massive star, and everybody's like, "What?" (Credit: DC Comics).

Stats on the flash:

• it would last 3-10 days (so "flash" is perhaps not the best word to describe it, except to astronomers, who think on million-year timescales at the smallest)
• it would equate to a temperature of 10,000 kelvin, or 17,540F
• it would travel at a max speed of 200 km/second or 124 miles/second
• it wouldn't show any evidence of nuclear synthesis, but hydrogen would be prevalent
• it would have a luminosity of 10^40-41 ergs/second, or 2.6 million-26 million times as bright as the Sun
• it would be brightest in UV light but a similarly strong blue component

So keep your transient-identifying, world-class UV-sensitive telescope's eyes open, and maybe you'll be the first one to see a black hole progenitor's final moments, before it Houdinis itself out of the visible universe.

Piro, A. (2013). TAKING THE “UN” OUT OF “UNNOVAE” The Astrophysical Journal, 768 (1) DOI: 10.1088/2041-8205/768/1/L14