The Top 13 Space Stories of 2006
The makings of life in space, dark matter in the spotlight, the first inflatable space station, and more
3 Cosmic Collision Brings Dark Matter Into View A violent collision has turned up the most direct evidence yet of dark matter...
10 Pluto DemotedPluto now falls under the quaint designation "dwarf planet"...
13 Probe Snaps Baby Picture of the Cosmos
A detailed snapshot of what the universe was like as a trillionth-of-a-second-old newborn...
22 Methane Rain Falls Mainly on Titan's PlainThe Huygens probe made a splat. "It landed in mud"...
45 Alien Planets Get Smaller, Fatter, Faster, and Hotter
This year ushered some of the oddest extrasolar plaents ever found...
48 Nearby Universe MappedAstrophysicists have produced the most detailed full-sky map of the nearby universe...
51 Ice Volcanoes Seen On Saturnian Moon
NASA's Cassini probe showed a geyser shooting jets of water and fine icy particles hundreds of miles into space...
56 Comet Dust Records Solar System Chaos
One-third of a milligram of dust from comet Wild 2 landed on Earth last January...
67 Complex Organic Molecules Formed in Outer SpaceAstronomers have identified eight new complex molecules in space...
75 Astro-Hotel LaunchedBigelow Aerospace last July launched Genesis 1, the first inflatable space station...
93 Renegade Planet Pair Defy ExplanationA pair of celestial objects circling one another have fed a growing debate over the dividing line between planets and stars...
96 Strange Swirls Spotted at Venus's PoleVenus is Earth's near-twin in size and mass, yet bafflingly different in other particulars...
100 Saturn SunburstThe Cassini spacecraft captured an extraordinary backlit image of Saturn and its gossamer rings...
Sunday, March 4, 2007
it is... science!
it is.... science!
World's Biggest Binoculars
Astronomers open a new window onto the universe. 12.11.2006
One Giant Step for a Small, Crowded Country
Are the Japanese moving to the moon? 11.28.2006
A Death in the Solar System
Say good-bye to the old nine planets. Say hello to a whole new celestial family. 11.27.2006
Map: Space Junk
Garbage zipping through space could shatter a spececraft or crash into Earth. 11.16.2006
Did Life Begin In Space?
Interstellar organic molecules suggest that Earth may have been seeded by the cosmos. 11.9.2006
Mars Exposed
With the new Mars Reconnaissance Orbiter zeroing in on its target, NASA scientists prepare for an unprecedented look at the Red Planet's ancient seas and modern ice fields—key sites in the ongoing search for life. 10.10.2006
Mars Exposed
An unprecedented look at the Red Planet's ancient seas and modern ice fields. 10.1.2006
The Buzz on NASA
The Apollo 11 pioneer charts a radical course back into space. 9.13.2006
The Future of NASA
Michael Griffin is gearing NASA up to build a moon base. Is he paving the way to Mars or jeopardizing the future of American space exploration? 9.1.2006
Map: X-Ray Vision Shows How a Galaxy Cluster Grows
New X-ray data unveils the dynamics of galaxy cluster Abell 3266. 9.1.2006
Fossils of the First Life
New fossil analysis puts the beginning of life more than 3.4 billion years ago. 9.1.2006
Sky Lights: Confused About Your Direction?
If you lack a sense of personal trajectory, astronomers can help. 9.1.2006
Blinded by Science: Hawking's Exit Strategy
Why is one of the thinking community's heavy hitters dabbling in doomsday prophecy? 9.1.2006
Map: Earth's Fourth Dimension
A gravitational rainbow points to our planet's invisible topography. 8.14.2006
20 Things You Didn't Know About... Meteors
The Perseids may be a washout this year, but that's no excuse to ignore valuable news about X-ray slaps, the Tears of St. Lawrence, and the fiddly meteor/meteoroid/asteroid/meteorite distinction.
World's Biggest Binoculars
Astronomers open a new window onto the universe. 12.11.2006
One Giant Step for a Small, Crowded Country
Are the Japanese moving to the moon? 11.28.2006
A Death in the Solar System
Say good-bye to the old nine planets. Say hello to a whole new celestial family. 11.27.2006
Map: Space Junk
Garbage zipping through space could shatter a spececraft or crash into Earth. 11.16.2006
Did Life Begin In Space?
Interstellar organic molecules suggest that Earth may have been seeded by the cosmos. 11.9.2006
Mars Exposed
With the new Mars Reconnaissance Orbiter zeroing in on its target, NASA scientists prepare for an unprecedented look at the Red Planet's ancient seas and modern ice fields—key sites in the ongoing search for life. 10.10.2006
Mars Exposed
An unprecedented look at the Red Planet's ancient seas and modern ice fields. 10.1.2006
The Buzz on NASA
The Apollo 11 pioneer charts a radical course back into space. 9.13.2006
The Future of NASA
Michael Griffin is gearing NASA up to build a moon base. Is he paving the way to Mars or jeopardizing the future of American space exploration? 9.1.2006
Map: X-Ray Vision Shows How a Galaxy Cluster Grows
New X-ray data unveils the dynamics of galaxy cluster Abell 3266. 9.1.2006
Fossils of the First Life
New fossil analysis puts the beginning of life more than 3.4 billion years ago. 9.1.2006
Sky Lights: Confused About Your Direction?
If you lack a sense of personal trajectory, astronomers can help. 9.1.2006
Blinded by Science: Hawking's Exit Strategy
Why is one of the thinking community's heavy hitters dabbling in doomsday prophecy? 9.1.2006
Map: Earth's Fourth Dimension
A gravitational rainbow points to our planet's invisible topography. 8.14.2006
20 Things You Didn't Know About... Meteors
The Perseids may be a washout this year, but that's no excuse to ignore valuable news about X-ray slaps, the Tears of St. Lawrence, and the fiddly meteor/meteoroid/asteroid/meteorite distinction.
The God Experiments
The God Experiments
Five researchers take science where it's never gone before.
by John Horgan -->
Three years ago, the British evolutionary biologist Richard Dawkins became a guinea pig in an experiment. Neuroscientist Michael Persinger claimed he had induced religious experiences in subjects by stimulating specific regions of their brains with electromagnetic pulses. Dawkins, renowned for his biological theories as well as for his criticism of religion, volunteered to test Persinger's electromagnetic device—the "God machine," as some journalists dubbed it. "I've always been curious to know what it would be like to have a mystical experience," Dawkins said shortly before the experiment. Afterward, he admitted on BBC that he was "very disappointed" that he did not experience "communion with the universe" or some other spiritual sensation.
Many researchers, like Persinger, view the brain as the key to understanding religion. Others focus on psychological, genetic, and biochemical origins. The science of religion has historical precedents, with Sigmund Freud and William James addressing the topic early in the last century. Now modern researchers are applying brain scans, genetic probes, and other potent instruments as they attempt to locate the physiological causes of religious experience, characterize its effects, perhaps replicate it, and perhaps even begin to explain its abiding influence.
The endeavor is controversial, stretching science to its limits. Religion is arguably the most complex manifestation of the most complex phenomenon known to science, the human mind. Religion's dimensions range from the intensely personal to the cultural and political. Additionally, researchers come to study religious experiences with very different motives and assumptions. Some of them hope that their studies will inform and enrich faith. Others see religion as an embarrassing relic of our past, and they want to explain it away.
"Even when the neural basis of religion has been identified, it remains a plausible interpretation of any conceivable neuropsychological facts that there is a genuine experience of God," notes Fraser Watts, a psychologist and theologian at the University of Cambridge and an Anglican vicar. A major funder of research on religion is the John Templeton Foundation, started in 1987 by the Christian financier John Templeton to promote "collaboration" between science and religion.
The theories described below illustrate the diversity of scientific approaches to understanding religion. All these theories are tentative at best, and some will almost certainly turn out to be wrong. The field suffers from vague terminology, disagreement about what exactly "religion" is, and which of its aspects are most important. Does religion consist primarily of behaviors, such as attending church or following certain moral precepts? Or does it consist of beliefs—in God or in an afterlife? Is religion best studied as a set of experiences, such as the inchoate feelings of connection to the rest of nature that can occur during prayer or meditation? Comparing studies is often an exercise in comparing apples and oranges. Nonetheless, the science merits close attention.
Inventing God
Stewart Guthrie, an anthropologist at Fordham University in New York, is in the explain-it-away camp of researchers. Noting the plethora of gods that populate the world's religions, many with minds and emotions similar to our own, Guthrie argues that the belief in supernatural beings is a result of an illusion that arises from our tendency to project human qualities onto the world. Religion "may be best understood as systematic anthropomorphism," he writes in his book, Faces in the Clouds.
Anthropomorphism is an adaptive trait that enhanced our ancestors' chances of survival, he adds. If a Neanderthal mistook a tree creaking outside his cave for a human assailant, he suffered no adverse consequences beyond a moment's panic. If the Neanderthal made the opposite error—mistaking an assailant for a tree—the consequences might have been dire. In other words, better safe than sorry. Over millennia, as natural selection bolstered our unconscious anthropomorphic tendencies, they reached beyond specific objects and events to encompass all of nature, goes Guthrie's theory, until we persuaded ourselves that "the entire world of our experience is merely a show staged by some master dramatist."
Humans are not alone in this trait. In The Descent of Man, Charles Darwin noted that many "higher mammals" share the human propensity "to imagine that natural objects and agencies are animated by spiritual or living essences." As an example, he recalled watching his dog growl at a parasol lifted off the ground by a gust of wind.
Andrew Newberg, a neuroscientist at the University of Pennsylvania, has focused on the tendency of people from different religious traditions to report similar mystical experiences, which typically involve sensations of self-transcendence and "oneness." These commonalities indicate that the visions stem from the same neural processes, Newberg hypothesizes. To test his theory, Newberg has scanned the brains of more than 20 adherents of spiritual practices, including Christian prayer and Tibetan Buddhist meditation. He uses a technique called single-photon-emission-computed tomography, or SPECT, a variant of the better-known positron-emission tomography, PET.
The chief advantage of SPECT is that it can capture the brains of meditators in a relatively natural setting. The subject meditates not in the SPECT chamber itself but in a separate room. When a subject—a Franciscan nun, in one case—feels her ordinary self "dissolving into Christ consciousness," as she describes it, a radioactive fluid is injected into her body through an intravenous tube; the fluid travels to her brain and becomes trapped in nerve cells there. The nun then goes to the SPECT chamber, where a computer-controlled camera scans her brain. The resulting image reveals levels of neural activity in the moment immediately after she received the radioactive fluid, when she presumably was still immersed in contemplation.
Next Page » [1] 2 3
Five researchers take science where it's never gone before.
by John Horgan -->
Three years ago, the British evolutionary biologist Richard Dawkins became a guinea pig in an experiment. Neuroscientist Michael Persinger claimed he had induced religious experiences in subjects by stimulating specific regions of their brains with electromagnetic pulses. Dawkins, renowned for his biological theories as well as for his criticism of religion, volunteered to test Persinger's electromagnetic device—the "God machine," as some journalists dubbed it. "I've always been curious to know what it would be like to have a mystical experience," Dawkins said shortly before the experiment. Afterward, he admitted on BBC that he was "very disappointed" that he did not experience "communion with the universe" or some other spiritual sensation.
Many researchers, like Persinger, view the brain as the key to understanding religion. Others focus on psychological, genetic, and biochemical origins. The science of religion has historical precedents, with Sigmund Freud and William James addressing the topic early in the last century. Now modern researchers are applying brain scans, genetic probes, and other potent instruments as they attempt to locate the physiological causes of religious experience, characterize its effects, perhaps replicate it, and perhaps even begin to explain its abiding influence.
The endeavor is controversial, stretching science to its limits. Religion is arguably the most complex manifestation of the most complex phenomenon known to science, the human mind. Religion's dimensions range from the intensely personal to the cultural and political. Additionally, researchers come to study religious experiences with very different motives and assumptions. Some of them hope that their studies will inform and enrich faith. Others see religion as an embarrassing relic of our past, and they want to explain it away.
"Even when the neural basis of religion has been identified, it remains a plausible interpretation of any conceivable neuropsychological facts that there is a genuine experience of God," notes Fraser Watts, a psychologist and theologian at the University of Cambridge and an Anglican vicar. A major funder of research on religion is the John Templeton Foundation, started in 1987 by the Christian financier John Templeton to promote "collaboration" between science and religion.
The theories described below illustrate the diversity of scientific approaches to understanding religion. All these theories are tentative at best, and some will almost certainly turn out to be wrong. The field suffers from vague terminology, disagreement about what exactly "religion" is, and which of its aspects are most important. Does religion consist primarily of behaviors, such as attending church or following certain moral precepts? Or does it consist of beliefs—in God or in an afterlife? Is religion best studied as a set of experiences, such as the inchoate feelings of connection to the rest of nature that can occur during prayer or meditation? Comparing studies is often an exercise in comparing apples and oranges. Nonetheless, the science merits close attention.
Inventing God
Stewart Guthrie, an anthropologist at Fordham University in New York, is in the explain-it-away camp of researchers. Noting the plethora of gods that populate the world's religions, many with minds and emotions similar to our own, Guthrie argues that the belief in supernatural beings is a result of an illusion that arises from our tendency to project human qualities onto the world. Religion "may be best understood as systematic anthropomorphism," he writes in his book, Faces in the Clouds.
Anthropomorphism is an adaptive trait that enhanced our ancestors' chances of survival, he adds. If a Neanderthal mistook a tree creaking outside his cave for a human assailant, he suffered no adverse consequences beyond a moment's panic. If the Neanderthal made the opposite error—mistaking an assailant for a tree—the consequences might have been dire. In other words, better safe than sorry. Over millennia, as natural selection bolstered our unconscious anthropomorphic tendencies, they reached beyond specific objects and events to encompass all of nature, goes Guthrie's theory, until we persuaded ourselves that "the entire world of our experience is merely a show staged by some master dramatist."
Humans are not alone in this trait. In The Descent of Man, Charles Darwin noted that many "higher mammals" share the human propensity "to imagine that natural objects and agencies are animated by spiritual or living essences." As an example, he recalled watching his dog growl at a parasol lifted off the ground by a gust of wind.
Andrew Newberg, a neuroscientist at the University of Pennsylvania, has focused on the tendency of people from different religious traditions to report similar mystical experiences, which typically involve sensations of self-transcendence and "oneness." These commonalities indicate that the visions stem from the same neural processes, Newberg hypothesizes. To test his theory, Newberg has scanned the brains of more than 20 adherents of spiritual practices, including Christian prayer and Tibetan Buddhist meditation. He uses a technique called single-photon-emission-computed tomography, or SPECT, a variant of the better-known positron-emission tomography, PET.
The chief advantage of SPECT is that it can capture the brains of meditators in a relatively natural setting. The subject meditates not in the SPECT chamber itself but in a separate room. When a subject—a Franciscan nun, in one case—feels her ordinary self "dissolving into Christ consciousness," as she describes it, a radioactive fluid is injected into her body through an intravenous tube; the fluid travels to her brain and becomes trapped in nerve cells there. The nun then goes to the SPECT chamber, where a computer-controlled camera scans her brain. The resulting image reveals levels of neural activity in the moment immediately after she received the radioactive fluid, when she presumably was still immersed in contemplation.
Next Page » [1] 2 3
Mind-Control Microbe
Mind-Control Microbe
A bug in your body can give you schizophrenia, make you have a car crash, or determine the sex of your child.
by Kathy A. Svitil
Five years ago, Oxford University zoologists showed that the parasite Toxoplasma gondii alters the brain chemistry of rats so that they are more likely to seek out cats. Infection thus makes a rat more likely to be killed and the parasite more likely to end up in a cat—the only host in which it can complete the reproductive step of its life cycle. The parasite also lives in the brain cells of thousands of species, including about 60 million supposedly symptom-free Americans. Studies over the past few years have suggested that toxoplasmosis infections in humans, too, may cause behavioral changes—from subtle shifts to outright schizophrenia. Two studies this year add even weirder twists.
U.S. Geological Survey biologist Kevin Lafferty has linked high rates of toxoplasmosis infection in 39 countries with elevated incidences of neuroticism, suggesting the mind-altering organism may be affecting the cultures of nations.
Stranger still, parasitologist Jaroslav Flegr of Charles University in Prague thinks T. gondii could also be skewing our sex ratios. When he looked at the clinical records of more than 1,800 babies born from 1996 to 2004, he noted a distinct trend: The normal sex ratio is 104 boys born for every 100 girls, but in women with high levels of antibodies against the parasite, the ratio was 260 boys for every 100 girls. Exactly how the parasite might be tipping the odds in favor of males isn't understood, but Flegr points out that it is known to suppress the immune system of its hosts, and because the maternal immune system sometimes attacks male fetuses in very early pregnancy, the parasite's ability to inhibit the immune response might protect future boys as well as itself.
"Our present study was rejected by eight journals, usually without any formal review," says Flegr, who had the same problem publishing an earlier one showing that infection more than doubles the odds of a person having a traffic accident. "People don't like the possibility that their behavior and life are manipulated by a parasite," he says.
If altering our culture and causing car crashes weren't bad enough, toxoplasma may actually wheedle their genes into our genomes.
There are plenty of other theories about what affects the reproductive sex ratio. Some of them are actually true.
A bug in your body can give you schizophrenia, make you have a car crash, or determine the sex of your child.
by Kathy A. Svitil
Five years ago, Oxford University zoologists showed that the parasite Toxoplasma gondii alters the brain chemistry of rats so that they are more likely to seek out cats. Infection thus makes a rat more likely to be killed and the parasite more likely to end up in a cat—the only host in which it can complete the reproductive step of its life cycle. The parasite also lives in the brain cells of thousands of species, including about 60 million supposedly symptom-free Americans. Studies over the past few years have suggested that toxoplasmosis infections in humans, too, may cause behavioral changes—from subtle shifts to outright schizophrenia. Two studies this year add even weirder twists.
U.S. Geological Survey biologist Kevin Lafferty has linked high rates of toxoplasmosis infection in 39 countries with elevated incidences of neuroticism, suggesting the mind-altering organism may be affecting the cultures of nations.
Stranger still, parasitologist Jaroslav Flegr of Charles University in Prague thinks T. gondii could also be skewing our sex ratios. When he looked at the clinical records of more than 1,800 babies born from 1996 to 2004, he noted a distinct trend: The normal sex ratio is 104 boys born for every 100 girls, but in women with high levels of antibodies against the parasite, the ratio was 260 boys for every 100 girls. Exactly how the parasite might be tipping the odds in favor of males isn't understood, but Flegr points out that it is known to suppress the immune system of its hosts, and because the maternal immune system sometimes attacks male fetuses in very early pregnancy, the parasite's ability to inhibit the immune response might protect future boys as well as itself.
"Our present study was rejected by eight journals, usually without any formal review," says Flegr, who had the same problem publishing an earlier one showing that infection more than doubles the odds of a person having a traffic accident. "People don't like the possibility that their behavior and life are manipulated by a parasite," he says.
If altering our culture and causing car crashes weren't bad enough, toxoplasma may actually wheedle their genes into our genomes.
There are plenty of other theories about what affects the reproductive sex ratio. Some of them are actually true.
Consciousness in a Cockroach
Consciousness in a Cockroach
Neuroscientists are teasing apart the insect nervous system, looking for clues to attention, consciousness, and the origin of the brain.
by Douglas Fox -->
To Nicholas Strausfeld, a tiny brain is a beautiful thing. Over his 35-year career, the neurobiologist at the University of Arizona at Tucson has probed the minute brain structures of cockroaches, water bugs, velvet worms, brine shrimp, and dozens of other invertebrates. Using microscopes, tweezers, and hand-built electronics, he and his graduate students tease apart—ever so gently—the cell-by-cell workings of brain structures the size of several grains of salt. From this tedious analysis Strausfeld concludes that insects possess "the most sophisticated brains on this planet.
" Strausfeld and his students are not alone in their devotion. Bruno van Swinderen, a researcher at the Neurosciences Institute (NSI) in San Diego, finds hints of higher cognitive functions in insects—clues to what one scientific journal called "the remote roots of consciousness."
"Many people would pooh-pooh the notion of insects having brains that are in any way comparable to those of primates," Strausfeld adds. "But one has to think of the principles underlying how you put a brain together, and those principles are likely to be universal."
The findings are controversial.
"The evidence that I've seen so far has not convinced me," says Gilles Laurent, a neuroscientist at Caltech. But some researchers are considering possibilities that would shock most lay observers. "We have literally no idea at what level of brain complexity consciousness stops," says Christof Koch, another Caltech neuroscientist.
"Most people say, 'For heaven's sake, a bug isn't conscious.' But how do we know? We're not sure anymore. I don't kill bugs needlessly anymore."
Heinrich Reichert of the University of Basel in Switzerland has become more and more interested in "the relatedness of all brains." Reichert's own studies of the brain's origin lead to a little-known ancestor, a humble creature called Urbilateria, which wriggled and swam nearly a billion years ago. The granddaddy of all bilaterally symmetrical animals, Urbilateria is the forebear of spiders, snails, insects, amphibians, fish, worms, birds, reptiles, mammals, crabs, clams—and yes, humans.
There is, of course, good reason to view insect brains as primitive—at least quantitatively. Humans possess 100,000,000,000 brain cells. A cockroach has nearly 1,000,000 brain cells; a fruit fly, only 250,000. Still, insects exercise impressive information management: They pack neurons into their brains 10 times more densely than mammals do. They also use each brain cell more flexibly than mammals. Several far-flung tendrils of a single neuron can each act independently—boosting computing power without increasing the number of cells. Somehow that circuitry allows a honeybee, with barely a million neurons on board, to meander six miles from its hive, find food, and make a beeline directly home. Few humans could do the same even with a map and a compass.
On the surface, the brains of insects and mammals look nothing alike. Only from studies of cell-by-cell connections does the astounding similarity emerge. One afternoon Christopher Theall, one of Strausfeld's Ph.D. students, shows me his own experimental setup for tapping into a portion of the cockroach brain known as the mushroom body. This mushroom-shaped brain structure is thought to be analogous to the mammalian hippocampus, a brain component involved in forming memories of places.
"What we're trying to do," says Theall, as we enter a cramped laboratory, "is scale down the techniques that have been used in rat and primate brains—scale them down to a brain that's a thousandth the size."
Theall's experimental apparatus rests on a table that floats on vibration-absorbing pressurized air. Even a cart rattling in the hallway outside could undermine the experiment. Because Theall needs to record nerve impulses amounting to just one 1/10,0000 of a volt, the table is enclosed in a cage that blocks electromagnetic interference from the room's lights. Working under a microscope with tweezers, steady hands, and held breath, Theall fashions copper wire only twice the diameter of a red blood cell into electrodes that he will insert into the cockroach's brain.
"They're fragile," he says. "Even a breeze from a door opening can ruin a couple hours of work."
After 20 hours of prep, Theall is ready to do the experiment. Twisting a knob while gazing into the microscope, he sinks the electrode into the roach's brain until it rests in one of the mushroom bodies. During the experiment, Theall will train this cockroach to earn a reward: If the insect points its antenna toward certain landmarks, it will receive thrilling puffs of peanut-butter odor. Theall wants to eavesdrop on neurons to determine how they contribute to learning the location of those landmarks.
The final step of the experiment—dissection of the mushroom body—allows Theall to see the two or three cells he has monitored. Because the cells have absorbed copper released from the electrode, he can tell them apart from the 200,000 other brain cells in the mushroom body. Theall then traces the structure of each cell using pen, paper, and a light box. It is like drawing a gnarled oak tree down to the last twig, and reconstructing a single cell can take two days. Theall, a typical student in Strausfeld's lab, will perform hundreds of experiments like these before his Ph.D. is complete.
Theall and Strausfeld never know which of the tens of thousands of cells they're going to hit when they tap into a roach's mushroom body. By repeating the experiment over and over, however, they are assembling a picture of what types of cells exist, how those cells function during tasks of place memory, and what kinds of connections they form with other cells. Cell by cell, they hope to piece together the structure's circuitry.
Paired structures called mushroom bodies in a cockroach brain play a key role in navigation.
During a chat in his office, Strausfeld sketches a mushroom body, pointing out several parallels to the hippocampus, the brain center devoted to memory and place location in mammals. The base consists of thousands of parallel nerve fibers running together like the grain in a piece of wood. Further up from the base, the fibers send out connections in loops that look like jug handles on a freeway; this is the shape that has earned this part of the brain the name "mushroom body." The connections rejoin the fibers higher up, near the top. Strausfeld suspects these looping pathways bring together related pieces of information, like the sights and smells of various landmarks that a roach encounters, one after another, as it travels to and from its home.
"The geometry of the structure," he says, "is so strangely reminiscent of the [human] hippocampus." Strausfeld and others are looking for clues as to whether the similarities result from a deep and ancient kinship or simply from analogous solutions that evolved independently to aid survival.
In his underground laboratory at the Neurosciences Institute, van Swinderen is observing a fly suspended in what amounts to a miniature IMAX theater. The setup is designed to monitor the focus of attention in a fly's brain. An LED screen wraps around the fly, displaying a sequence of flashing objects in front of its eyes, two objects at a time. Right now, it's an X and a square. The X is flickering 12 times per second and the square 15 times per second.
-->Next Page » [1] 2
Neuroscientists are teasing apart the insect nervous system, looking for clues to attention, consciousness, and the origin of the brain.
by Douglas Fox -->
To Nicholas Strausfeld, a tiny brain is a beautiful thing. Over his 35-year career, the neurobiologist at the University of Arizona at Tucson has probed the minute brain structures of cockroaches, water bugs, velvet worms, brine shrimp, and dozens of other invertebrates. Using microscopes, tweezers, and hand-built electronics, he and his graduate students tease apart—ever so gently—the cell-by-cell workings of brain structures the size of several grains of salt. From this tedious analysis Strausfeld concludes that insects possess "the most sophisticated brains on this planet.
" Strausfeld and his students are not alone in their devotion. Bruno van Swinderen, a researcher at the Neurosciences Institute (NSI) in San Diego, finds hints of higher cognitive functions in insects—clues to what one scientific journal called "the remote roots of consciousness."
"Many people would pooh-pooh the notion of insects having brains that are in any way comparable to those of primates," Strausfeld adds. "But one has to think of the principles underlying how you put a brain together, and those principles are likely to be universal."
The findings are controversial.
"The evidence that I've seen so far has not convinced me," says Gilles Laurent, a neuroscientist at Caltech. But some researchers are considering possibilities that would shock most lay observers. "We have literally no idea at what level of brain complexity consciousness stops," says Christof Koch, another Caltech neuroscientist.
"Most people say, 'For heaven's sake, a bug isn't conscious.' But how do we know? We're not sure anymore. I don't kill bugs needlessly anymore."
Heinrich Reichert of the University of Basel in Switzerland has become more and more interested in "the relatedness of all brains." Reichert's own studies of the brain's origin lead to a little-known ancestor, a humble creature called Urbilateria, which wriggled and swam nearly a billion years ago. The granddaddy of all bilaterally symmetrical animals, Urbilateria is the forebear of spiders, snails, insects, amphibians, fish, worms, birds, reptiles, mammals, crabs, clams—and yes, humans.
There is, of course, good reason to view insect brains as primitive—at least quantitatively. Humans possess 100,000,000,000 brain cells. A cockroach has nearly 1,000,000 brain cells; a fruit fly, only 250,000. Still, insects exercise impressive information management: They pack neurons into their brains 10 times more densely than mammals do. They also use each brain cell more flexibly than mammals. Several far-flung tendrils of a single neuron can each act independently—boosting computing power without increasing the number of cells. Somehow that circuitry allows a honeybee, with barely a million neurons on board, to meander six miles from its hive, find food, and make a beeline directly home. Few humans could do the same even with a map and a compass.
On the surface, the brains of insects and mammals look nothing alike. Only from studies of cell-by-cell connections does the astounding similarity emerge. One afternoon Christopher Theall, one of Strausfeld's Ph.D. students, shows me his own experimental setup for tapping into a portion of the cockroach brain known as the mushroom body. This mushroom-shaped brain structure is thought to be analogous to the mammalian hippocampus, a brain component involved in forming memories of places.
"What we're trying to do," says Theall, as we enter a cramped laboratory, "is scale down the techniques that have been used in rat and primate brains—scale them down to a brain that's a thousandth the size."
Theall's experimental apparatus rests on a table that floats on vibration-absorbing pressurized air. Even a cart rattling in the hallway outside could undermine the experiment. Because Theall needs to record nerve impulses amounting to just one 1/10,0000 of a volt, the table is enclosed in a cage that blocks electromagnetic interference from the room's lights. Working under a microscope with tweezers, steady hands, and held breath, Theall fashions copper wire only twice the diameter of a red blood cell into electrodes that he will insert into the cockroach's brain.
"They're fragile," he says. "Even a breeze from a door opening can ruin a couple hours of work."
After 20 hours of prep, Theall is ready to do the experiment. Twisting a knob while gazing into the microscope, he sinks the electrode into the roach's brain until it rests in one of the mushroom bodies. During the experiment, Theall will train this cockroach to earn a reward: If the insect points its antenna toward certain landmarks, it will receive thrilling puffs of peanut-butter odor. Theall wants to eavesdrop on neurons to determine how they contribute to learning the location of those landmarks.
The final step of the experiment—dissection of the mushroom body—allows Theall to see the two or three cells he has monitored. Because the cells have absorbed copper released from the electrode, he can tell them apart from the 200,000 other brain cells in the mushroom body. Theall then traces the structure of each cell using pen, paper, and a light box. It is like drawing a gnarled oak tree down to the last twig, and reconstructing a single cell can take two days. Theall, a typical student in Strausfeld's lab, will perform hundreds of experiments like these before his Ph.D. is complete.
Theall and Strausfeld never know which of the tens of thousands of cells they're going to hit when they tap into a roach's mushroom body. By repeating the experiment over and over, however, they are assembling a picture of what types of cells exist, how those cells function during tasks of place memory, and what kinds of connections they form with other cells. Cell by cell, they hope to piece together the structure's circuitry.
Paired structures called mushroom bodies in a cockroach brain play a key role in navigation.
During a chat in his office, Strausfeld sketches a mushroom body, pointing out several parallels to the hippocampus, the brain center devoted to memory and place location in mammals. The base consists of thousands of parallel nerve fibers running together like the grain in a piece of wood. Further up from the base, the fibers send out connections in loops that look like jug handles on a freeway; this is the shape that has earned this part of the brain the name "mushroom body." The connections rejoin the fibers higher up, near the top. Strausfeld suspects these looping pathways bring together related pieces of information, like the sights and smells of various landmarks that a roach encounters, one after another, as it travels to and from its home.
"The geometry of the structure," he says, "is so strangely reminiscent of the [human] hippocampus." Strausfeld and others are looking for clues as to whether the similarities result from a deep and ancient kinship or simply from analogous solutions that evolved independently to aid survival.
In his underground laboratory at the Neurosciences Institute, van Swinderen is observing a fly suspended in what amounts to a miniature IMAX theater. The setup is designed to monitor the focus of attention in a fly's brain. An LED screen wraps around the fly, displaying a sequence of flashing objects in front of its eyes, two objects at a time. Right now, it's an X and a square. The X is flickering 12 times per second and the square 15 times per second.
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