A do-it-yourself map of touch

http://www.maxplanckflorida.org/fitzpatricklab/homunculus/experiment/

A website shows how your sense of touch maps to sites in your brain:

This map shows the parts of the body next to the areas of the brain that process their sense of touch. The eyes and hands have a lot of space devoted to them; other parts, not so much.

Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/.

 

WASHINGTON – Our fingertips are very sensitive to touch, much more than are our arms or legs. Different parts of the brain respond to the touch sensations of our fingers, arms, legs and other body parts. But this can be hard to picture. An educational website now makes learning about these sensory systems and the brain easy. Anyone can do it. All you need is a friend, some toothpicks, a pen, paper and glue.
Mapping how well different parts of the body respond to touch “is an easy way to get people excited about science and thinking critically,” says Rebekah Corlew. She’s a neuroscientist at the Max Planck Institute for Neuroscience in Jupiter, Fla. Corlew came up with the idea for mapping our touch sensitivity as a way to teach students about their somatosensory cortex. That’s the area of our brain that responds to our sense of touch. She presented information on the new website November 16 at the Society for Neuroscience Meeting.
When you want to get a good sense of how soft something is, such as a cat’s fur, you touch it with your fingers, not your arm or the back of your hand. Your fingertips are far more sensitive to touch. They have more nerve endings than your arm or back. Our fingers’ high degree of sensitivity makes us able to tackle many delicate tasks, from rapid texting to surgery.
Having lots of nerve endings and a great sensitivity requires that the brain reserve more space to process all of the information arriving from that region’s nerves. So the area of your brain devoted to sensing fur on your fingertips is much larger than that responsible for sensing a bug on your leg.
These brain areas have been mapped by many scientists and portrayed as a visual map. Presented as a map on the brain, as pictured at right, it looks like a jumble of body parts laid over the cortex  — the outermost layer of the brain closest to the skull. Brain areas that process touch from the thumb lie right next to those for the eye. The areas responsive to the toes are next to those for the genitals.
Many times, scientists represent the map of a physical system on a human figure called a homunculus (Ho-MUN-keh-lus).  When presented as a model of a person, or cortical homunculus, each body part is scaled to the brain real estate that responds to it. In this format people look like odd puppets, with huge and sensitive hands and tongues and tiny insensitive torsos and legs.
Anyone can make a homunculus of their personal touch sensitivity. All you need is a friend to place two toothpicks on various parts of the body. Start by putting them far apart, maybe 60 millimeters (2.4 inches) apart, on your arm. Can you feel both toothpicks — or just one? Have the friend touch you again, this time with the toothpicks closer together. Do you still feel two toothpicks? Keep doing this until the pair feel like just one toothpick. Now do the same thing on other areas of the body. Stop when you only felt one poke instead of two and record the distance between the toothpicks.
As you measure different body parts, you will quickly realize that your palm can distinguish two points even when they are very close together. But your back can’t make this two-point discrimination even when the toothpicks are relatively far apart.
At this point, many high school and college classes might do some math to figure out how “big” their hand should look on their homunculus. As a general rule, if a body part detects a very small difference between two points, the area devoted to that body part on the homunculus is correspondingly huge. As the distance that can resolve two toothpicks shrinks, the brain area gets bigger. This means it is inversely proportional: As one feature grows, another shrinks in size or impact.
The inverse proportion of each body part is calculated, mathematically, as 1 divided by the smallest distance needed for two-point discrimination in the target area. So if you measured 0.375 centimeter (or 0.15 inch) as the smallest distance your hand could detect two toothpicks, the inverse proportion would be 1 divided by 0.375 — or a ratio of 2.67.

This is my cortical “homunculus,” which I mapped with the help of a new website. My hands are very sensitive to touch and therefore appear large. Because my torso and arms are less sensitive, they appear small.

R. Corlew/Homunculus Mapper

To draw your own homunculus, you can plot out the inverse proportion of each body part onto graph paper. Here, the inverse proportion is portrayed by the number of boxes on the graph paper. This can take a lot of time. The images often don’t look very much like a person, either.The new Homunculus Mapper website takes out the math and the graphing paper. It has you make a pair of two-point discrimination cards, using five different pairs of toothpicks. One pair is attached 60 millimeters (2.4 inches) apart. The others are 30 millimeters (1.2 inches), 15 millimeters (0.59 inch), 7.5 millimeters (0.30 inch) and 3.5 mm (0.15 inch) apart. In the last spot on the cards, place a single toothpick. Perform the two-point discrimination test with a partner. Write down the number for the smallest distance you detected two points for your hand, arm, back, forehead, leg and foot.
Now go to the website. Once you select an avatar, enter the numbers that you measured. You don’t need to find their inverse. As you select the numbers from the dropdown menus on the left of the screen, you will see your avatar change. Hands will become gigantic, while the torso shrinks. A computer program takes the measurements you enter on the site and converts them automatically. It provides an easy way to visualize how your sense of touch maps to your brain.
The site is free to use. It also comes with a full set of instructions, both for making the toothpick cards and for performing the test. In future, Corlew hopes to add an instruction video to make the process even easier.

Scientists Say: Your weekly word

 https://student.societyforscience.org/article/scientists-say-your-weekly-word

Scientists Say (noun, “SIGH-en-tists Sae”)

This is a weekly feature from our science inspiration blog, Eureka! Lab. Every week, science education writer Bethany Brookshire highlights a new science word, from allele to zoonosis. Each word has a definition and is used in a sentence to help you understand the meaning. There’s even an audio recording, so you can hear exactly how to pronounce the term. All the words covered so far are listed below. Got a word you want to know about? Tweet to @eureka_labs and put in a request!



http://www.sciencebuddies.org/science-fair-projects/project_guide_index.shtml

Fossils show sign of ancient vampire microbes.

 

 An amoeba (top cell) is eating the innards of green algae. Fossils from around 750 million years ago show evidence of similar vampirelike predation.

https://student.societyforscience.org/article/fossils-show-sign-ancient-vampire-microbes?mode=topic&context=60 

Meteorites likely wiped out Earth’s earliest life.

https://student.societyforscience.org/article/meteorites-likely-wiped-out-earth%E2%80%99s-earliest-life?mode=topic&context=60


 




Repeatedly during its early history, Earth was bombarded by space rocks larger in diameter than the state of Utah. Such collisions likely killed off any emerging life on the planet’s surface — probably again and again. The last of these death rocks struck around 4.3 billion years ago. At least that’s the estimate that scientists propose in the July 31 Nature. This date offers an upper limit to how long our planet may have continuously sustained life.
Earth appears to be around 4.6 billion years old. For its first 800,000 years, the planet was a hellish place. That’s why geologists call this the Hadean eon — after Hades, the Greek god of the underworld. Debris left over from the solar system’s creation regularly slammed into Earth. This would have boiled away the early ocean and coated the planet with molten rock.
But scientists think that it was during this chaotic time that life began.
“If life on Earth emerged before [a] final sterilizing impact, it may have been completely erased,” says Simone Marchi. That’s right: Rendered extinct. “Life would have had to start all over again,” concludes this planetary scientist at the Southwest Research Institute in Boulder, Colo. She led the new study.
So much material struck Earth during the Hadean that it would have built up the planet’s surface by a height equal to that of Mount Everest. These impacts shaped the emergence of tectonic plates. Those relatively thin, migrating slabs of rock make up Earth’s surface, floating over a layer of molten rock below. Over time, those slabs continually rise out of the molten rock and submerge again. Their activity, which renews Earth’s surface, plays out over billions of years.
It also means that few surface rocks remain that are older than around 3.8 billion years old. So our planet holds no obvious record of events earlier than that.
In search of records for even earlier collisions, Marchi and her colleagues looked to the moon. Why? Its surface lacks the recycling action of plate tectonics, so the moon still shows scars from early asteroid impacts.

Scientists can determine the ages of those very ancient impacts by crater counting. As a crater ages, newer meteorites pock its surface at each new impact site. During Apollo missions to the moon, astronauts retrieved moon rocks. Back on Earth, geologists dated rocks collected from lunar craters. Scientists can estimate the age of the moon’s large and old craters by counting the number of smaller, fresher ones within the older ones.
Marchi’s team used this information to estimate the number, frequency and size of asteroids that likely impacted early Earth. Of course this works only if they assume both had a similar impact history.
The team then created a computer program to simulate Earth’s early asteroid bombardment. And the moon data suggest that asteroid impacts became smaller and less frequent with time. The computer also suggested that every bit of Earth’s surface had at some point been covered in a magma-oozing crater created by an impact.
Three to seven asteroids larger than 500 kilometers (roughly 310 miles) across probably struck Earth during this early time. At least, that's what the computer program indicates. Any of these could have vaporized all of the planet’s surface water. This hot, sizzling rock and lava would likely have destroyed any life then living on the surface.
The last of these life-sterilizing impacts took place 4.27 billion years ago, the researchers estimate. Fossils preserve evidence of life on Earth going back only 3.8 billion years (although some scientists dispute that earliest evidence).
Geochemist Jeffrey Bada works at the Scripps Institution of Oceanography in La Jolla, Calif. He believes that a better understanding of early asteroid bombardment will help researchers probing the origins of life. Earth’s really big asteroid smashups would have obliterated any cells that had evolved, he says. “Life could not have started prior to that and survived.”

Early Earth survived a billion years of asteroid impacts | Science News

Stephen Hawking: “We will have to find homes elsewhere in the universe”

http://elpais.com/elpais/2015/09/25/inenglish/1443171082_956639.html“Merry Christmas.” The unmistakable robotic voice belonging to the most famous scientist on the planet rings out along the promenade at El Camisón beach in Tenerife, prompting laughter among the tourists gathered round him. “It’s Stephen Hawking,” they whisper to each other, as they jostle to see him.

The laws of science are sufficient to explain the origin of the universe. It is not necessary to invoke God”

“It’s a joke he likes: it makes people laugh,” says Pat, one of the team that follows him everywhere, to explain the rather un-seasonal greeting. The 73-year-old Hawking is visiting the Canary Islands to promote the third biennial Starmus festival, a unique international gathering focused on celebrating astronomy, space exploration, music, art and allied sciences such as biology and chemistry founded by Garik Israelian, an astronomer at the Canarian Institute for Astrophysics in Tenerife. The 2016 edition will bring together around a dozen Nobel laureates, along with many other famous figures from the worlds of art and science, astronomy and space exploration.
Hawking, who recently saw his remarkable life portrayed in the Oscar-winning movie The Theory of Everything, is able to write using a sensor in his cheek, one of the few muscles he is still able to move. He uses several software programs to help him communicate, but it can sometimes still take him up to two hours to answer a simple question – although he does have a special button that cracks jokes.

I would tell a young Spanish scientist to go to America. They value science because it pays off in technology”

A woman in a bathing suit approaches Hawking, saying: “Thanks for your sense of humor, Stephen.” This happens all the time, says one of his team: “His books about astrophysics and his work have made him popular around the world.” He is accompanied by seven people on the trip, among them doctors and close friends. Hawking agrees to answer EL PAÍS’s questions, and discusses the need to conquer space if humanity is to survive, as well as the dangers that artificial intelligence poses, and the future for science in Spain.
Question. Despite the difficulties involved, you’ve increased your public appearances. You keep a dizzying schedule of trips, lectures, interviews, festivals… almost like a rock star. Why do you do it?
Answer. I feel a duty to inform the public about science.
Q. Is there anything that you would like to do in life and still haven’t?
A. Go into space with Virgin Galactic.
Q. In one of your most recent books you focused on the theories that could unite relativity and quantum physics. What will the next one be about?
A. Go into my life against the odds.

My disability has been a help in a way. It has freed me from teaching or sitting on boring committees, and given me more time to think and do research”

Q. Spain, like many other countries, has cuts its science budget, prompting many young scientists to go abroad to continue their work. What would you say to a Spanish youngster who is considering whether or not to become a scientist?
A. Go to America. They value science because it pays off in technology.
Q. You recently launched a very ambitious initiative to search for intelligent life in our galaxy. A few years ago, though, you said it would be better not to contact extraterrestrial civilizations because they could even exterminate us. Have you changed your mind?
A. If aliens visit us, the outcome could be much like when Columbus landed in America, which didn’t turn out well for the Native Americans. Such advanced aliens would perhaps become nomads, looking to conquer and colonize whatever planets they can reach. To my mathematical brain, the numbers alone make thinking about aliens perfectly rational. The real challenge is to work out what aliens might actually be like.

I believe everyone can, and should have a broad picture of how the universe operates, and our place in it”

Q. You have said information can survive a black hole. What does that mean for the average person, especially if he or she ends up falling into a black hole?
A. Falling into a black hole is like going over Niagara Falls in a canoe, if you paddle fast enough, you can get away. Black holes are the ultimate recycling machine, what comes out is the same as what went in but it’s reprocessed.
Q. In 2015 the theory of relativity turns 100. What you would say to Einstein if you could speak to him, and what do you expect from science in the next 100 years?
A. Einstein wrote a paper in 1939 in which he claimed matter couldn’t be compressed beyond a certain point, ruling out black holes.
Q. Why should we fear artificial intelligence?
A. Computers will overtake humans with AI at some point within the next 100 years. When that happens, we need to make sure the computers have goals aligned with ours.
Q. What do you think our fate as a species will be?
A. I think the survival of the human race will depend on its ability to find new homes elsewhere in the universe, because there’s an increasing risk that a disaster will destroy Earth. I therefore want to raise public awareness about the importance of space flight. I have learnt not to look too far ahead, but to concentrate on the present. I have so much more I want to do.
Q. What would you say to the Spanish prime minister, who has approved major cuts to science spending?

Computers will overtake humans with AI at some point within the next 100 years. When that happens, we need to make sure the computers have goals aligned with ours”

A. The Spanish are very interested in science and cosmology. They were great readers of my book, A Brief History of Time. It is important that we all have a good understanding of science and technology. Science and technology are changing our world dramatically, and it is important to ensure that these changes are in the right directions. In a democratic society, this means that we all need to have a basic understanding of science, so we can make informed decisions ourselves, rather than leave them to the experts. Of course you have to simplify. Most people don’t have time to master the very mathematical details of theoretical physics. But I believe everyone can, and should have a broad picture of how the universe operates, and our place in it. This is what I have tried to convey in my books and lectures.
Q. Do you think one can be a good scientist and believe in God?
A. I use the word, God, in an impersonal sense, like Einstein did, for the laws of nature.
Q. You said God is unnecessary to explain the universe as it is. Do you think humans would one day abandon religion and God?
A. The laws of science are sufficient to explain the origin of the universe. It is not necessary to invoke God.

I have learnt not to look too far ahead, but to concentrate on the present. I have so much more I want to do”

Q. People who use wheelchairs face many difficulties in leading a normal life. Having experienced difficulties yourself, what is your message to people who have to use wheelchairs?
A. Although I was unfortunate enough to get motor neurone disease, I have been very fortunate in almost everything else. I was lucky to be working in theoretical physics, one of the few areas in which disability was not a serious handicap, and to hit the jackpot with my popular books. My advice to other disabled people would be, concentrate on things your disability doesn’t prevent you doing well, and don’t regret the things it interferes with. Theoretical physics is one of the few fields in which being disabled is no handicap. It’s all in the mind. I must admit, I do tend to drift off to thinking about physics or black holes when I get left behind in the conversation. In fact, my disability has been a help in a way. It has freed me from teaching or sitting on boring committees, and given me more time to think and do research.
Q. What’s so important about Starmus?
A. Starmus 3 is not only about black holes, a subject I have done important work on, but it also includes music and the arts. Starmus 3 is where serious science finds a wider audience where intellectual thought, nuance and complexity are celebrated, where the way scientists work is explored and where new ideas are harnessed.