Researchers discover fundamental scaling rule that differentiates primate and carnivore brains

PASADENA, Calif.--Everybody from the Tarzan fan to the evolutionary biologist knows that our human brain is more like a chimpanzee's than a dog's. But is our brain also more like a tiny lemur's than a lion's?

In one previously unsuspected way, the answer is yes, according to neuroscientists at the California Institute of Technology. In the current issue of the Proceedings of the National Academy of Sciences (PNAS), graduate student Eliot Bush and his professor, John Allman, report their discovery of a basic difference between the brains of all primates, from lemurs to humans, and all the flesh-eating carnivores, such as lions and tigers and bears.

The difference lies in the way the percentage of frontal cortex mass increases as the species gets larger. The frontal cortex is the portion of brain just behind the forehead that has long been associated with reasoning and other "executive" functions. In carnivores, the frontal cortex becomes proportionately larger as the entire cortex of the individual species increases in size--in other words, a lion that has a cortex twice the size of another carnivore's also has a frontal cortex twice the size.

By contrast, primates like humans and apes tend to have a frontal cortex that gets disproportionately larger as the overall cortex increases in size. This phenomenon is known as "hyperscaling," according to Bush, the lead author of the journal article.

What this says about the human relationship to the tiny lemurs of Madagascar is that the two species likely share a developmental or structural quirk, along with all the other primates, that is absent in all the carnivores, Bush explains. "The fact that humans have a large frontal cortex doesn't necessarily mean that they are special; relatively large frontal lobes have developed independently in aye-ayes among the lemurs and spider monkeys among the New World monkeys."

Bush and Allman reached their conclusions by taking the substantial histological data from the comparative brain collection at the University of Wisconsin at Madison. The collection, accumulated over many years by neuroscientist Wally Welker, comprises painstaking data taken from well over 100 species.

Bush and Allman's innovation was taking the University of Wisconsin data and running it through special software that allowed for volume estimations of the various structures of the brain in each species. Their results compared 43 mammals (including 25 primates and 15 carnivores), which allowed them to make very accurate estimations of the hyperscaling (or the lack thereof) in the frontal cortex.

The results show that in primates the ratio of frontal cortex to the rest of the cortex is about three times higher in a large primate than in a small one. Carnivores don't have this kind of systematic variation.

The hyperscaling mechanism is genetic, and was presumably present when the primates first evolved. "Furthermore, it is probably peculiar to primates," says Allman, who is Hixon Professor of Neurobiology at Caltech.

The next step will be to look at the developmental differences between the two orders of mammals by looking at gene expression differences. Much of this data is already available through the intense efforts in recent years to acquire the complete genomes of various species. The human genome, for example, is already complete, and the chimp genome is nearly so.

"We're interested in looking for genes involved in frontal cortex development. Changes in these may help explain how primates came to be different from other mammals," Bush says.

At present, the researchers have no idea what the difference is at the molecular level, but with further study they should be able to make this determination, Allman says. "It's doable."

The article is titled "The scaling of frontal cortex in primates and carnivores." For a copy of the article, contact Jill Locantore, PNAS communications specialist, at 202-334-1310, or e-mail her at jlocantore@nas.edu.

The PNAS Web site is at http://www.pnas.org.

For more information on Bush and Allman's research, go to the Web site http://allmanlab.caltech.edu/people/bush/3d-histol/3d-brain-recon.html

 

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Robert Tindol
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Zombie Behaviors Are Part of Everyday Life, According to Neurobiologists

PASADENA, Ca.--When you're close to that woman you love this Valentine's Day, her fragrance may cause you to say to yourself, "Hmmm, Chanel No. 5," especially if you're the suave, sophisticated kind. Or if you're more of a missing link, you may even say to yourself, "Me want woman." In either case, you're exhibiting a zombie behavior, according to the two scientists who pioneered the scientific study of consciousness.

Longtime collaborators Christof Koch and Francis Crick (of DNA helix fame) think that "zombie agents"--that is, routine behaviors that we perform constantly without even thinking--are so much a central facet of human consciousness that they deserve serious scientific attention. In a new book titled The Quest for Consciousness: A Neurobiological Approach, Koch writes that interest in the subject of zombies has nothing to do with fiction, much less the supernatural. Crick, who for the last 13 years has collaborated with Koch on the study of consciousness, wrote the foreword of the book.

The existence of zombie agents highlights the fact that much of what goes on in our heads escapes awareness. Only a subset of brain activity gives rise to conscious sensations, to conscious feelings. "What is the difference between neuronal activity associated with consciousness and activity that bypasses the conscious mind?" asks Koch, a professor at the California Institute of Technology and head of the Computation and Neural Systems program.

Zombie agents include everything from keeping the body balanced, to unconsciously estimating the steepness of a hill we are about to climb, to driving a car, riding a bike, and performing other routine yet complex actions. We humans couldn't function without zombie agents, whose key advantage is that reaction times are kept to a minimum. For example, if a pencil is rolling off the table, we are quite able to grab it in midair, and we do so by executing an extremely complicated set of mental operations. And zombie agents might also be involved, by way of smell, in how we choose our sexual partners.

"Zombie agents control your eyes, hands, feet, and posture, and rapidly transduce sensory input into stereotypical motor output," writes Koch. "They might even trigger aggressive or sexual behavior when getting a whiff of the right stuff.

"All, however, bypass consciousness," Koch adds. "This is the zombie in you."

Zombie actions are but one of a number of topics that Koch and Crick have investigated since they started working together on the question of the brain basis of consciousness. Much of the book concerns perceptual experiments in normal people, patients, monkeys, and mice, that address the neuronal underpinnings of thoughts and actions.

As Crick points out in his foreword, consciousness is the major unsolved problem in biology. The Quest for Consciousness describes Koch and Crick's framework for coming to grips with the ancient mind-body problem. At the heart of their framework is discovering and characterizing the neuronal correlates of consciousness, the subtle, flickering patterns of brain activity that underlie each and every conscious experience.

The Quest for Consciousness: A Neurobiological Approach will be available in bookstores on February 27. For more information, see www.questforconsciousness.com. For review copies, contact Ben Roberts at Roberts & Company Publishers at (303) 221-3325, or send an e-mail to bwr@roberts-publishers.com.

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Robert Tindol
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Caltech Nobel Laureate Ed Lewisto be Feted at Campus Celebration

PASADENA—Edward Lewis, who pioneered the modern understanding of how genes regulate the development of specific regions of the body, will be honored at a special celebration on the California Institute of Technology campus at 4 p.m. Wednesday, February 4.

A member of the Caltech faculty, Lewis won the Nobel Prize in 1995 in physiology or medicine for his seminal work on fruit fly mutations, which led to a fundamental understanding of the relation between genes and embryonic development in humans as well as flies. Currently the Morgan Professor of Biology, Emeritus, Lewis continues an active fruit-fly research regimen that began when he was a high school student in the 1930s.

Guest lecturer Howard Lipshitz will present "From Fruit Flies to Fallout: Ed Lewis and His Science." A colleague of Lewis's for the last two decades, Lipshitz is editor of the new book Genes, Development, and Cancer: The Life and Work of Edward B. Lewis, which was published in the USA this month by Kluwer Academic Publishers in Norwell, Mass.

According to the publisher, Lewis's scientific research "is the bridge linking experimental genetics as conducted in the first half of the 20th century, and the powerful molecular genetic approaches that revolutionized the field in its last quarter." Much less widely known are Lewis's contributions to understanding the links between ionizing radiation and cancer, as well as the closely related issues concerning nuclear-weapons testing policy.

A native of Wilkes-Barre, Pennsylvania, Lewis earned his bachelor's degree at the University of Minnesota in 1939, and his Ph.D. at Caltech, where he has been on the faculty ever since, except as a U.S. Army Air Corps meteorologist in the Pacific theatre during World War II.

In the 1950s Lewis played a key role in discovering and explaining the role of homeotic genes--that is, genes that influence how the undifferentiated cells in a fertilized embryo separate into a head and a tail end, and how the eyes, legs, antennae, and other organs all form in their correct positions.

These genes are "highly conserved," as geneticists say, because the genes are similar in all organisms and play a role in the development of all animals, from fruit flies to mice to humans.

The lecture will be held in 119 Kerckhoff (the Norman Davidson Lecture Hall) on the west side of campus. Parking is available in the nearby parking structure on Wilson Avenue.

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The length of the gaze affects human preferences, new study shows

PASADENA, Calif.—Beauty may be in the eye of the beholder, but a new psychophysical study from the California Institute of Technology suggests that the length of the beholding is important, too.

In an article appearing in the December 2003 issue of the journal Nature Neuroscience, Caltech biology professor Shinsuke Shimojo and his colleagues report that human test subjects asked to choose between two faces will spend increasingly more time gazing at the face that they will eventually choose as the one more attractive. Also, test subjects will typically choose the face that has been preferentially shown for a longer time by the experimenter. In addition, the results show that the effect of gaze duration on preference also holds true for choices between abstract geometric figures.

The findings show that human preferences may be more fundamentally tied to "feedback" between the very act of gazing and the internal, cognitive prototype of attractiveness than was formerly assumed. Earlier work by other researchers has relied on the "attractiveness template," which assumes that an individual's ideal conception of beauty has somehow been imprinted on his or her brain due to early exposures to other people's faces, such as the mother.

In fact, Shimojo says, the new results come from experiments especially designed to minimize the influence of earlier biases and existing preferences. Even when images of faces have been computer-processed to eliminate possible biases due to ethnic origins and even such trivial factors as hairstyles, the results still show strongly that the gaze is subconsciously oriented toward the eventual choice. This holds true even more strongly when a test subject is asked to choose between two abstract geometric figures, suggesting that the slightly lower tendency to fix the gaze on the eventual choice of two faces is influenced by existing selection biases that cannot be totally controlled.

The findings in Nature Neuroscience comprise two experiments. The first was the choice of the more attractive face, in which all the test subjects were asked to rate the faces from 1 (very unattractive) to 7 (very attractive). The average rating for each face was then calculated so that faces in pairs could be matched in different ways.

In the "face-attractiveness-easy task" the faces were paired according to gender, race, and neutrality of facial expressions, but comprised a choice of a "very unattractive" face with a "very attractive" face. Five test subjects were then shown 19 face pairs and were asked to choose the face they preferred. A video camera recorded the movements of their eyes as they directed their attention from one face on the screen to the other.

The results showed that the likelihood of gaze of the test subjects started from chance (50 percent) but rose above 70 percent of their time gazing at the face till they chose that face.

Even more striking was the difference in gaze devoted to the "face-attractiveness-difficult task," in which 30 pairs of faces were matched according to the closeness in which they had been ranked for attractiveness. In this experiment, the test subjects spent up to 83 percent of their time gazing at the face they would choose immediately before their decision response, suggesting that the gaze is even more important when there is little difference in the features of stimuli themselves.

The test subjects were also asked to choose the least attractive face, as well as the rounder face, and the results also showed that the length of the gaze was an important indicator of the eventual choice. In addition, the subjects were asked to choose between abstract geometric shapes, and the length of gaze also correlated highly with the eventual choice.

The second experiment is "gaze manipulation," in which the faces are not shown simultaneously, but in sequences of varying duration on the two sides of the computer screen. In other words, one face was shown for a longer time (900 milliseconds) than the other face (300 milliseconds), and as a control, the faces were also shown to other subjects in the center of the screen in an alternating sequence.

The results show that the face shown for a longer time tends to be chosen at chance level (50 percent) with only two repetitions of the sequence, but about 59 percent of the time with 12 repetitions. This suggests that the duration of the gaze can influence the choice. However, this manipulation did not work in the control experiment without gaze shift, as mentioned above, indicating that it is not mere exposure time, but rather active gaze shift, that made the differences.

In sum, the results indicate that active orienting by gaze shift is wired into the brain and that humans use it all the time, albeit subconsciously, Shimojo says. One example is our preference for good eye contact with people whom we are engaging in conversation.

"If I look directly into your eyes, then glance at your ears, you can immediately tell that I've broken eye contact, even if we're some distance apart," Shimojo explains. "This shows that there are subtle clues to what's in the mind."

In addition to Shimojo, the other authors are Claudiu Simion, a graduate student in biology at Caltech; Christian Scheier, a former postdoctoral researcher in Shimojo's lab; and Eiko Shimojo, of the School of Human Studies/Psychology at Bunkyo Gakuin University in Japan. Shinsuke Shimojo and Claudiu Simion contributed equally to the work. 

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National Human Genome Research Institute awards $12 million, five-year grant to "WormBase"

PASADENA, Calif.— The Caltech-led WormBase project, an ongoing multi-institutional effort to make genetic information on the experimental animal known as C. elegans freely available to the world, has been augmented with a new $12 million grant from the National Human Genome Research Institute. The money will be distributed over five years for ongoing work on the genome database, which since its inception in 2000 has become a major resource for biomedical researchers as well as biologists attempting to better understand individual genes and how they interrelate. According to Caltech biology professor Paul Sternberg, leader of the project, WormBase has already succeeded in making available on-line the complete genome sequence (100.2 million base pairs) of the nematode, plus an almost complete sequence for the closely related organism C. briggsae, as well as genes for some 20 parasitic nematode species. In addition, the project makes available a huge amount of experimental data pertaining to the nematode.

The completed sequences will be vital for an emerging research effort that includes the new double-strand RNA interference technique for understanding a gene's function, and the fruits of the sequencing effort are already apparent. There are now 23,000 such experiments in WormBase, along with 280,000 DNA expression ("chip") microarray observations, as well as detailed information on the expression of more than 1,600 of the worm's 20,000 genes.

"For the future, researchers will look at interactions between genes, which means that there are 20,000-squared possibilities for the interactions of two genes alone," says Sternberg. "Also, our future effort will include working with similar databases of the genomes of other organisms, such as the mouse, fruit fly, and yeast, for shared software and shared conceptual vocabularies.

"The ultimate purpose is to allow medical researchers to get the information more easily," he adds.

The human-worm connection may seem tenuous to people outside biology, but it is known that the two organisms have similarity in about 40 percent of their genes. A very realistic motivation for the funding of genome sequencing of other organisms has been to provide data for comparisons of genes that are of interest in the quest to better understand human disease. Thus, a cancer researcher who discovers that a certain gene is expressed in cancer cells can use the WormBase to see if the gene exists in nematodes, and if so, what is known about the gene's function.

Exploring the fundamental relationships between genes from species separated by hundreds of millions of years of evolution is expected to be a cornerstone of 21st-century biological innovation. Improved knowledge of how a gene is expressed in one species--and as time goes on, how two or more genes interact--will provide new approaches for dealing with human disease and will almost certainly be the foundation for some important medical advances.

The role of WormBase in 21st-century medicine will continue to be as a resource for knowledge. Already the wormbase.org site is fully searchable in a number of ways, including by genes, cells (the nematodes have only 959, and all are clearly understood and clearly visible under a microscope), and biological processes, as well as by names of researchers.

Information in WormBase comes from teams at the two centers that sequence the C. elegans and C. briggsae genomes--a team at the Sanger Institute, in England, led by Richard Durbin, and one at Washington University, led by John Spieth. The innovative software used to display the information in WormBase was developed by Lincoln Stein of the Cold Spring Harbor Laboratory, where the WormBase Web server is located.

Fourteen individuals at Caltech are currently involved in the WormBase project, including nine biologists and three computer experts.

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Why Fearful Animals Flee—or Freeze

PASADENA, Calif. –In most old-fashioned black-and-white horror flicks, it always seems there's some hapless hero or heroine who gets caught up in a life-threatening situation. Instead of making the obvious choice--to run like hell--he/she freezes in place. That decision, alas, leads to their ultimate demise.

While their fate was determined by bad scriptwriting, scientists already know that in real life, environment and experience influence defensive behaviors. Less understood are the neural circuits that determine such decisions. Now, in an article in the May 1 issue of the Journal of Neuroscience, researchers at the California Institute of Technology have developed an experimental model using mice that can map and manipulate the neural circuits involved in such innate behaviors as fear.

Raymond Mongeau, Gabriel A. Miller, Elizabeth Chiang, and David J. Anderson, in work performed at Caltech, manipulated either a flight or freeze reaction in mice through the use of an ultrasonic auditory stimulus, and further, were able to alter the mouse's behavior by making simple changes in the animal's environment. They also found that flight and freezing are negatively correlated, suggesting that a kind of competition exists between these alternative defensive motor responses. Finally, they have begun to map the potential circuitry in the brain that controls this competition.

"Fear and anxiety are important emotions, especially in this day and age," says Anderson, a Caltech professor of biology and an investigator with the Howard Hughes Medical Institute. "We know a lot about how the brain processes fear that is learned, but much less is known about innate or unlearned fear. Our results open the way to better understanding how the brain processes innately fearful stimuli, and how and where anxiety affects the brain to influence behavior."

Using the ultrasonic cue, the researchers were able to predict and manipulate the animal's reaction to a fearful situation. They found that mice exposed to the ultrasonic stimulus in their home cage (a familiar environment) predominantly displayed a flight response. Those placed in a new cage (an unfamiliar environment), or treated with foot shocks the previous day, primarily displayed freezing and less flight.

Anderson noted that in previous fear "conditioning" experiments, where mice learn to fear a neutral tone associated with a footshock, the animals show only freezing behavior and never flight, even though in the wild, flight is a normal and important fear response to predators. This suggests that the ultrasonic stimulus used by Anderson and colleagues is tapping into brain circuits that mediate natural, or innate, fear responses that include flight as well as freezing.

What causes the shift from flight to freezing behavior? Probably high anxiety and stress, say the authors, caused by an unfamiliar environment or the foot shocks. The researchers suggest that freezing requires a higher threshold level of anticipatory fear (the heroine inside a dark, spooky house) before it can be elicited by the ultrasound.

Most brain researchers believe the brain uses a hierarchy of neural systems to determine which defensive behaviors, like flight or freezing, to use. These range from an evolutionary older neural system that generates "quick and dirty" defensive strategies, to more evolved systems that produce slower but more sophisticated reactions. These systems are known to interact, but the neural mechanisms that decide which response wins out are not understood.

One of the goals of their work was to map the brain regions that control the behaviors triggered by the fear stimulus, to observe whether any change in brain activity correlated with the different defensive behaviors. They achieved this, all the way down to the resolution of a single neuron, by mapping the expression pattern of the c-FOS gene, a so-called "immediate early gene" that is turned on when neurons are excited. The switching on of the c-FOS gene can therefore be used as an indication of neuronal activation.

A map of the c-FOS expression patterns during flight vs. freezing revealed that mice displaying freezing behavior had neural activity in different regions of the brain than those that fled. Some of these regions were previously known to inhibit each other, providing a possible explanation for the apparent competition between flight and freezing observed in the intact animal.

Anderson notes that more work needs to be done to pin down where and how anxiety modifies defensive behavior. "This system may also provide a useful model for understanding the neural substrates of human fear disorders, like panic and anxiety," says Anderson, "as well as provide a model for developing drugs to treat them."

Contact: Mark Wheeler (626) 395-8733 wheel@caltech.edu

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Caltech biology professor to directresearch program on brain signaling

California Institute of Technology biologist Mary Kennedy has been named project director for a $4 million federal project grant to better understand how the brain processes signals. Progress could lead to new insights into how drugs can be better custom-designed to treat a host of neurodegenerative disorders, mental illnesses, and disabilities, including Alzheimer's disease, depression, and schizophrenia.

The funding will come from the National Institute of Neurological Disorders and Stroke, a component of the National Institutes of Health (NIH). According to Kennedy, who is the Allen and Lenabelle Davis Professor of Biology at Caltech, the five-year project is innovative because it will integrate advanced computational methods with experiments to better analyze and model calcium signaling in the brain. In addition to Kennedy's research group at Caltech, the program will involve research teams from the Salk Institute, Cold Spring Harbor Laboratory, and the University of North Carolina.

"Another aspect of this research that is quite new is the application of these kinds of methods at the molecular level," she says. "This is important because, for about 20 years or so, it wasn't really possible to be rigorously quantitative about the biochemical functions of synapses at the molecular level. This was because we didn't know all the molecules that were involved."

With new advances, especially the completion of the Human Genome Project, it is now time for a new phase in research on the molecular mechanisms of brain functions, according to Kennedy. In addition to basic improvements in knowledge of how brain signaling works, the research program could also lead indirectly to pharmaceutical advances.

"Neurological and mental diseases result, in part, from derangements in regulation of synaptic transmission," Kennedy says. "In a type of neuronal structure known as dendritic spines -- so named because they sort of look like spines -- calcium influx through a certain type of receptor is a principal regulator of synaptic strength, or plasticity. Thus, calcium can lead to increases or decreases, of varying durations, in synaptic strength."

The program includes four projects and a core that will provide new computer software. One project will use a computer program called MCell to develop and test models of calcium dynamics in spines. Another will rely on microscopy to study the organization of calcium sources and sinks in spines, as well as calcium distribution. A third, which will be centered in Kennedy's lab, will develop and test kinetic models of enzymes regulated by calcium; and a fourth will use advanced imaging techniques to measure calcium signals and their regulation in individual spines.

The program will be highly interdisciplinary, Kennedy says. Three physicists will be among the team members in her lab. Work at the other institutions, as well, will involve specialists from disciplines outside biology.

"Once we have a better quantitative understanding of signaling, it will be possible to ask much 'cleaner' questions about what kind of drugs will treat certain conditions, and under what circumstances."

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Contact: Robert Tindol (626) 395-3631

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New Insight Into How Flies Fly

PASADENA, Calif. –How does a fly fly and why should we care? To the first, says Michael Dickinson, a professor of bioengineering at the California Institute of Technology, the short answer is different from what we have thought, and he and his colleagues used a dynamically-scaled flapping robot (aka Robofly), a free flight arena (aka Fly-O-Rama), and a 3D, infrared visual flight simulator (Fly-O-Vision) to prove it.

And we should care, says Dickinson, because the simple motion of a flying fly links a series of fundamental and complex processes within both the physical and biological sciences. Studying a fly may eventually lead to a model that will provide insight into the behavior and robustness of complex systems in general, and, for roboticists, may help them in the design of flying robots that mimic nature.

In a paper entitled "The Aerodynamics of Free Flight Maneuvers in Drosophila," Steven Fry of the University of Zurich, Rosalyn Sayaman, a Caltech research assistant, and Dickinson show how tiny insects use their wings to generate enough torque to overcome inertia, and not--as conventional wisdom has held--friction. The paper will appear in the April 18 issue of the journal Science.

Flies and other dipterans (insects within the family that includes houseflies, hoverflies, and fruit flies), are capable of making rapid 90-degree turns, called saccades, at "extraordinary" speeds, says Dickinson, less than 50-thousandths of a second. That's faster, he says, "than a human eye can blink." To make the turn, a fly must generate enough torque, or twisting force, to offset two forces working against it--the inertia of its own body and the viscous friction of air.

Until now, it's always been assumed that viscosity, a resistance to flow, is the enemy for small critters, while inertia is the bane of larger animals like birds. But the theory has never been tested.

To study the aerodynamics of active flight maneuvers, the researchers employed infrared, three-dimensional, high-speed video (the Fly-O-Vision) to capture the fruit fly, Drosophila melanogaster, performing saccades in free flight. The animals were released in a large, enclosed arena (the Fly-O-Rama), and lured toward a vertical cylinder laced with a drop of vinegar. As the flies approach the cylinder, it looms within their field of view, triggering a rapid turn that helps the fly avoid a collision.

Many flies performed saccades within the intersecting fields of view of the three cameras, which allowed the researchers to film the turn, measure the wing and body position throughout the maneuver, and calculate the velocity of its path.

The improved resolution of the 3D video showed that, despite its small size and slow speed (relative to other animals), the fly performed a banked turn, similar to those observed in larger fly species, first accelerating, then slowing as it changed heading, then accelerating again at the end of the turn. This suggests that the time and velocity of the small fly are dominated by body inertia and not friction.

To see if the measured patterns of wing motion were sufficient to explain the saccades, the researchers played the sequences through a dynamically scaled robotic model (you guessed it, Robofly) to measure the aerodynamic forces as they vary by time. They found that the time and torque they calculated based on the fly's body morphology and body motion from the video matched "amazingly well," says Dickinson, with the calculations derived from the wing motion of the robot. These results, he notes, further support the notion that even in small insects the torques created by the wings act primarily to overcome inertia and not friction.

Although these experiments were performed on tiny fruit flies, says Dickinson, the results impact nearly all insects, because the importance of inertia over friction increases with the size of the animal. The results also provide a basis for future research on the neural and mechanical basis of insect flight, and, for roboticists, may offer insights for the design of biomimetic flying devices. It may also yield a little respect for the common fly. As Rosalyn Sayaman puts it on her web page, "I now love flies. I used to just shoo and swat. Now, I can't even swat anymore."

Note to Editors: Video and still photos are available.

Contact: Mark Wheeler (626) 395-8733 wheel@caltech.edu

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Six Caltech Professors Awarded Sloan Research Fellowships

PASADENA, Calif.— Six Caltech professors recently received Alfred P. Sloan Research Fellowships for 2003.

The Caltech recipients in the field of chemistry are Paul David Asimow, assistant professor of geology and geochemistry, Linda C. Hsieh-Wilson, Jonas C. Peters, and Brian M. Stoltz, assistant professors of chemistry. In mathematics, a Sloan Fellowship was awarded to Danny Calegari, associate professor of mathematics, and in neuroscience, to Athanassios G. Siapas, assistant professor of computation and neural systems.

Each Sloan Fellow receives a grant of $40,000 for a two-year period. The grants of unrestricted funds are awarded to young researchers in the fields of physics, chemistry, computer science, mathematics, neuroscience, computational and evolutionary molecular biology, and economics. The grants are given to pursue diverse fields of inquiry and research, and to allow young scientists the freedom to establish their own independent research projects at a pivotal stage in their careers. The Sloan Fellows are selected on the basis of "their exceptional promise to contribute to the advancement of knowledge."

From over 500 nominees, a total of 117 young scientists and economists from 50 different colleges and universities in the United States and Canada, including Caltech's six, were selected to receive a Sloan Research Fellowship.

Twenty-eight former Sloan Fellows have received Nobel prizes.

"It is a terrific honor to receive this award and to be a part of such a tremendous tradition of excellence within the Sloan Foundation," said Stoltz. Asimow commented that he will use his Sloan Fellowship to "support further investigation into the presence of trace concentrations of water in the deep earth... I'm pleased because funds that are unattached to any particular grant are enormously useful for seeding new and high-risk projects that are not quite ready to turn into proposals." On his research, Peters said, "The Sloan award will provide invaluable seed money for work we've initiated in the past few months regarding nitrogen reduction using molecular iron systems."

The Alfred P. Sloan Research Fellowship program was established in 1955 by Alfred P. Sloan, Jr., who was the chief executive officer of General Motors for 23 years. Its objective is to encourage research by young scholars at a time in their careers when other support may be difficult to obtain. It is the oldest program of the Alfred P. Sloan Foundation and one of the oldest fellowship programs in the country.

Contact: Deborah Williams-Hedges (626) 395-3227 debwms@caltech.edu

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Caltech Professor Receives Award for Research into Mechanisms of Memory Formation

PASADENA, Calif.— How do we form short-term and long-term memories in the brain? A California Institute of Technology professor will try to answer this question and others. Athanassios Siapas, assistant professor of computation and neural systems, has been awarded a $445,120 grant by the James S. McDonnell Foundation for his project "Network Mechanisms of Memory Formation."

The establishment of long-term memories is a gradual process that involves intricate interactions across distributed networks of neurons in the brain. Until recently, the direct experimental observation of such interactions was not technically feasible. Using techniques that enable monitoring of the simultaneous activity of large numbers of single neurons across multiple brain areas, Siapas's research group will study the mechanisms that orchestrate memory formation in distributed brain circuits.

Understanding the fundamental principles that underlie memory formation and learning may offer insights into neurological disorders that affect memory, such as Alzheimer's disease, and may aid in finding a cure for such debilitating illnesses.

Siapas joined Caltech in January 2002, after conducting postdoctoral work at the Center for Learning and Memory at the Massachusetts Institute of Technology. Siapas also earned his PhD from MIT.

Founded in 1950 by aerospace pioneer James S. McDonnell, the James S. McDonnell Foundation was established to improve the quality of life, and has done so by contributing to the generation of new knowledge through its support of research and scholarship. In 2002 the foundation awarded approximately $16 million in grants. Since its inception, the McDonnell Foundation has awarded over $264 million in grants.

Contact: Deborah Williams-Hedges (626) 395-3227 debwms@caltech.edu

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