Discover Magazine Shorties

A selection of short articles

All articles by Susan Kruglinski

See to Feel, Feel to See

Neuroscientists are finding that self-evident notions about our senses -- that the eyes allow us to see, that our tactile senses allow us to feel -- may be only half the story. It seems sensory pathways are not discrete, as previously thought, but are complementary, allowing for some pretty strange phenomena when sensory input deviates from the norm.

The "rubber hand illusion" is a parlor trick that neurologists have been marveling over for years. A rubber hand is positioned to resemble a normal hand extending from a subject's arm, with the real hand hidden from sight. If the fake and real hands are stroked simultaneously and repeatedly with a paintbrush, the subject may feel the stroking on the rubber hand, as if her tactile sensations were transferred from her real hand to the disembodied hand. Henrik Ehrsson of University College, London and colleagues scanned the brains of subjects experiencing the illusion and found the premotor cortex to be activated when the subjects "felt" the rubber hand as their own.

"It seems the premotor cortex, which integrates vision and touch, is the area that matches the look of the hand and the feel of the hand," says Ehrsson. Because the brain tends to rely more on vision than any other sense, this illusion allows vision to take over as the catalyst for tactile sensation. "When there is a conflict between the look of the hand and the feel of the hand," says Ehrsson, "the brain tends to believe the vision."

But perhaps there is even more going on than that. University of California, San Diego neurologist V.S. Ramachandran and his student Shai Azoulai are studying an unusual blind man who can "see" his own hand when he passes it in front of what would be his peripheral vision. Just as vision feeds into somatic sensation for Ehrsson's subjects, somatic sensations seem to create the illusion of sight for this subject when he feels his hand before his eyes. Ramachandran attributes this to the multimodality of neurons, which creates reciprocity between sensory pathways. In fact, studies show that people who are partially blind may extend their region of vision by placing their hand in their blind spot. If neurons can indeed function in multiple roles, this versatility seems to be working in overdrive for Ramachandran's subject.

"One thing that's clear from this is that we need to replace the static view of the brain," says Ramachandran. "This suggests that there is a tremendous amount of back and forth interaction between the senses."

Classical One Minute, Quantum the Next

Traversing the boundary between classical and quantum physics, scientists at the University of Vienna have induced molecules to smoothly switch from quantum to classical behavior by simply heating them up and cooling them down.

Physicists distinguish between the classical world, our everyday experience of physics, where objects behave in a predictable manner, and the confounding quantum realm, where an object is perceived to be everywhere at once and doing who-knows-what. Using heat from a lasar, Anton Zeilinger, Markus Arndt and their team were able to manipulate fullerenes -- among the largest and most complex objects ever seen behaving in a quantum manner - so that they crossed the quantum threshold on demand.

When the molecules were heated above 1340 degrees Fahrenheit in an airless environment, they emitted photons, or thermal radiation, as they continued to heat up or began to cool down. This interaction with their surroundings held them in the classical state, just as, scientists believe, the warmth of our bodies and the air and light around us keep us from acting in a quantum way. When the temperature dropped below the threshold and the buckyballs no longer emitted radiation, they phased into a wave-like state, the quantum state. Reheated above the threshold, the molecules succumbed to "decoherence," the transition from the quantum state, and acted classically once again.

This was the first demonstration of decoherence caused by temperature change, and not interaction of a quantum particle with a second particle.

Controlling the physical state of minute objects has been a major concern in the quest to create quantum computers, where it is essential that the miniscule components consistently behave in their bizarre, quantum manner. "Studying decoherence has become more fashionable since the 1980s," said Arndt. "We are still trying to get to larger molecules. We would like to do this with a protein."

Stop That Hurricane!

For decades, meteorologists have tried to dream up ways to stop hurricanes. Clouds have been seeded, the ocean coated with oily liquids, and a super-absorbent polymer called Dyn-O-Storm has been sprinkled from planes to mop up hurricane moisture. Some have even wondered what would happen if a nuclear bomb was dropped upwind or an iceberg towed to the tepid waters that are the foundation of the hurricane. Critics find these schemes far-fetched, but when faced with more than 1600 dead from last season's storms, it is easy to understand why a few crackpots, visionaries and even top meteorologists continue the quest.

"I find most of these things are not very credible," says Bruce Albrecht, a meteorologist at the University of Miami. While the actions of hurricanes are much better understood than ever before, he says, "at this point, we still don't understand very well how hurricanes intensify or de-intensify."

Kerry Edwards, a meteorologist at MIT who was involved in the failed attempts to create a hurricane-stopping oil, has faith in some newer ideas about "designer perturbations," where computer models allow scientists to devise precisely placed, modestly sized interventions to weaken or divert an accumulating storm. Interventions could include cloud-seeding or oil slicks, but also newer ideas like orbiting power stations that beam microwaves to heat water vapor around the hurricane to weaken or divert it, or planes that release dark contrails that absorb and shield sunlight, cooling the water below.

"I'd venture to say that it will eventually happen," says Edwards. "Maybe not in our lifetimes, but it's plausible enough that it's almost bound to happen sooner or later."

But would messing with a hurricane be messing with an ecosystem? Hurricanes churn water, resulting in algae blooms that contribute to the marine food chain, and can drive global ocean currents that transport heat from the tropics to higher latitudes.

Despite these benefits, many scientists believe that stopping a few hurricanes probably wouldn't do the oceanic world much harm. And it is clear from the tragedies of this year that many lives can be saved if specific hurricanes are extinguished.

Edwards agrees: "Who wouldn't jump at the opportunity to prevent that sort of thing from happening again?"

The Mystery of Mirror Pain

Strangely, some people with injuries to one limb feel pain in the exact same spot on the opposite limb. Many doctors have dismissed this mirror pain as simply a result of overuse of the healthy body part, but neurologist Anne Louise Oaklander at Massachausetts General has found that the cause may be much weirder than anyone suspected. When nerves in one limb become injured, she says, nerves in the healthy limb inexplicably become identically damaged.

After noticing this bizarre occurrence in her patients with shingles, she carefully cut a specific nerve bundle in the hind paw of a rat. Amazingly, about half of the nerves in the exact same spot in the other paw died.

"This comes on incredibly quickly," said Oaklander. "We observed changes in the opposite limb as early as one day after surgery." She thinks that because the mirror injuries are spatially precise, the cause may be a neuronal signal - some kind of communication via the central nervous system from the injury to its opposite nerves. Why would the body perform such a trick?

"This is most likely a mechanism that operates in health, and perhaps allows us to coordinate information coming from both sides of the body," Oaklander said.

At the University of Colorado, Linda Watkins and her team of pain experts are also mulling over this mystery. They believes glial cells, the less-understood sister cells of neurons, may be the cause. Glia in the spinal cord have been recently found to activate when the immune system is challenged or pain-related neurons are firing. She believes the cells release inflammatory substances that could be toxic to nerves. She found that mirror pain in rats vanished when glial cells were inactivated.

Watkins thinks Oaklander's results are "fantastically important" and is hoping to collaborate with the Boston lab to better understand mirror pain. "It's one of those things that up until recently people were reticent to even tell their doctors," she said. "They thought they must be nuts. But my rats are not nuts."

Liquid Body Armor

Soldiers wear stiff bulletproof vests on their torsos, but their arms and legs are unprotected. The U.S. Army Research Laboratory is developing a so-called liquid armor, a product that can saturate the fabric of pants and shirtsleeves, making them resistant to injury yet flexible and lightweight. When hit hard by any object, the liquid stiffens into a solid, and the fabric becomes almost impenetrable.

This liquid transformation is actually an everyday occurrence. Stir a mixture of cornstarch and water and you will find that the more force you use, the more resistance you will feel, because the particles cluster and lock together. Stir a can of latex paint, and you will find the opposite: the faster you stir, the easier it gets. One of the liquid armor's developers, University of Delaware chemical engineer Norman Wagner, has spent years designing liquids with the useful property of becoming less viscous when churned or impacted. But he and his colleagues realized that stiffening liquids could also serve a purpose. "We tried to engineer it out of materials," he said, "but realized there are advantages to this phenomenon." If a liquid is resistant enough, perhaps it could stop a bullet.

Working with a variety of particles suspended in liquids, including nano-sized bits of silica in non-toxic polymers, Wagner has created liquids that add incredible strength to plastic fabrics such as Kevlar. Although ballistics tests are still being run, fabrics dipped in Wagner's liquids have passed rigorous knife and ice pick tests - when struck, the silica particles cluster and act as a shield against the blade.

Wagner hopes fabrics treated with the liquid can be used for bomb blankets, military tents, and even for civilian use in protective sporting and industrial gear.

Dinosaurs Topple Theory

That Africa broke from the ancient continent of Gondwanaland more than 120 million years ago, well before India and South America broke away, has been called into question by recent dinosaur digs. This so-called "Africa first" theory was based on the dearth of certain Cretaceous dinosaur bones found in Africa, seemingly the result of the landmass being isolated and unreachable to migrating animals. University of Chicago paleontologist Paul Sereno, known for finding some of the oldest dinosaur fossils on record, led an expedition in 2000 that uncovered a trove of African bones that may rewrite history for years to come. "This was probably the most successful expedition I will ever lead," he said. "And I've led a lot of expeditions."

Among the twenty tons of fossils the team found is the skull of a new 30-foot carnivore from the abelisaurid family, named Rugops primus or the "first wrinkle face." Sereno guesses that this animal may have been a scavenger, nibbling at carcasses much like a vulture or hyena. Rugops' skull was heavily veined and seems to have had ornamentation, possibly a covering of keratin, the hard shell that makes up our fingernails or the attractive bill of a toucan. The covering may have been colorful, to attract mates, or may have protected the face when scavenging carcasses (which can get quite messy). It could also be a precursor of a horn.

Because it was thought that the African continent was separate from Gondwanaland before their existence, paleontologists assumed that the wrinkle-faced family of dinosaurs had never set foot on the African continent. Rugops, however, is a mere 95 million years old. Sereno is certain that the animal could not have called Africa its home unless there were land connections between Africa and the other southern continents at that time. As he and his team carefully analyze their many other finds from 2000, Sereno believes there will be even more evidence to support this idea. He believes they have the bones of anilasaurids, a small predator something like a raptor that had also never been found in Africa.

"You've always got some diversity of opinion," he said of his new theory, "but I think there is a coming together of evidence that is hard to deny. We have unearthed a new chapter with lots of new players."

No Words, No Numbers

In the mid-1950s, one of the vanguard theories in linguistics was Benjamin Lee Whorf's hypothesis that language greatly influences, or even determines, thought. While most linguists have since dismissed this notion, Peter Gordon of Teacher's College at Columbia University is giving it another look. He recently studied an isolated 200 person tribe in the Amazon called the Pirahã, whose language is so restrictive, its only numerical words are translations of "one", "two", and "many". Gordon ran some tribe members through a series of tests that required them to compare small amounts of objects and duplicate groups of AA batteries and nuts. He found that the community could not count or discern the number of objects above three. Previous studies have shown that babies and many animals have an innate sense of "three", which could imply that a requirement for understanding the concept of "four" and above requires the language for it. "Is it the language, or the lack of practice doing it?" Gordon asks, but adds: "You can't really have a number system if you don't have the number words."

Other researchers conducted math studies with a larger tribe, producing results that may oppose Gordon's work. French linguist Pierre Pica and neuroscience and mathematics expert Stanislaw Dehaene designed computer tests for the Mundurukú tribespeople, who only have the language for numbers up to five. The scientists found that the Amazonians were surprisingly adept at estimating the totals or differences in comparing sets of up to 80 objects, doing almost as well as a control group of French speakers. Although the tribespeople could not succeed in exact calculations, the researchers say their work suggests that a rough number sense is inherent in all humans. "It shows very clearly that they have the rudiments of arithmetic," says Dehaene. "I would tend to think that this is part of the endowment of humanity and of many animals."

Black Holes Found To Be Not Weird

Black holes have always been thought to be the exotic oddballs of the universe. Einstein thought they were too bizarre to exist despite his own theory's predicting them, and within the last decade black hole guru Kip Thorne wrote that they are more fantastic than unicorns. But new evidence suggests not only that they are commonplace -- every galaxy seems to have one - but that they may be the foundation in the architecture of galaxies and even the very universe itself. Scientists are now wondering how the voraciously destructive relic of a dead star can be a primary constructive force in the cosmos.

Astrophysicists have recently found astonishingly ancient quasars thought to be powered by supermassive black holes. These behemoths are calculated to have existed about a billion years after the big bang, early in the life of the 14 billion year old universe. "This sets a very severe constraint on when supermassive black holes are formed," says Stuart Shapiro of the University of Chicago in Urbana Champaign. "The story of the black hole was considered to be an independent stage in the afterlife of a star," he says, referring to a star's collapse. Supermassive black holes had been thought to be the result of smaller black holes collapsing into each other, a process that does not fit well into this early time slot. "Now, it can be believed that the formation of supermassive black holes may be part of the initial birth of structure in the universe," Shapiro says.

This leads to the concept that black holes are somehow constructive, an idea that is also emerging among those who study contemporary black holes. Astronomers Andrea Ghez of UCLA and Reinhard Genzel of the Max Planck Institute for Extraterrestrial Physics have been able to close in on what may be considered their personal Moby Dick, a roiling mass at the center of our galaxy that appears to be a supermassive black hole. Correlating its size and mass with the various properties of the Milky Way, the scientists have come to the conclusion that this black hole and our galaxy may have formed simultaneously. "It seems whatever mechanism forms the bulk of the galaxy is also forming the black hole," says Ghez.

In fact, recent observations from separate groups of scientists seem to confirm that every large galaxy with a bulging center is swirling around a black hole of proportional gargantuan mass. They have even found intermediate sized black holes at the center of non-bulging, lower mass galaxies (which are now considered candidate start-ups of the earliest supermassive black holes). Many astrophysicists are now convinced that not only is galaxy formation tied to a central black hole, but that the black hole may dictate how the galaxy shapes itself. "People always thought of the galaxy as the parent and the black hole as the child that is born in the galaxy," says astrophysicist Avi Loeb of Harvard University. "They thought the black holes were just a curiosity."

Instead, black holes may be as essential to the universe as we know it as our sun is to life on Earth. And they may be as basic as the planets and the stars. "It is now clear that black holes are ubiquitous," says Loeb, "and that black hole formation is not exotic in any way."

Prions May Be Essential to Memory

Prions are thought to be bizarre incarnations of proteins, capable of decimating the brain in such illnesses as mad cow disease and Creutzfeld-Jakob disease. Since their discovery in 1982, no one has been able to figure out why shape-shifting prions exist. But neurologist Eric Kandel and his postdoc Kausik Si at Columbia University may have hit upon a raison d'être. Prions might be the key to the formation to long-term memory, which means that they might also be useful in other ways.

Kandel knew from his sea-slug research that the protein CPEB strengthened neural connections that were essential to long-term memory storage, but did not know how these connections could remain stable enough to last for days, months or years, as memories do. When Si noticed a passing resemblance in CPEB to prions found in yeast, they asked yeast-prion expert Susan Lindquist of the Whitehead Institute for Biomedical Research to fuse the slug protein with yeast protein. Sure enough, the new yeast-friendly CPEB acted like a prion, shifting shape and causing yeast proteins all around it to act identically in a very durable way. This unusual stability, the scientists speculate, could be the foundation of memory storage.

This process is so efficient, Lindquist says, "we think it's actually a very ancient, very old mechanism," one that presumably would be useful in other ways, although it is anybody's guess how.

"This is unlikely to be an isolated case in all of biology," says Kandel. "And I don't think this need be uniquely a brain function."