Category: Behavior/Psychology Page 17 of 27

Making Sense of Noise: Stephen Lisberger

On January 28, 2016

Imagine catching a ball thrown at you out of mid-air. Your response seems almost instinctive, like a reflex. However, this seemingly simple movement contains complex components: one must judge the ball’s arc to decide where it will intersect a particular height, and how fast one must move his hand to catch the accelerating ball.

This calculation requires an entire concert of neural signals, firing in a manner so precise that it produces an accurate estimate of the speed and direction of the ball’s trajectory. Add to this complicated model the fact that each individual neuron produces a certain amount of noise — that is, across various trials, the same neurons produce different firing responses to the same stimuli. These multiple layers of convolution would frustrate most, but Dr. Stephen Lisberger thrives upon it.

Screen Shot 2016-01-27 at 12.47.43 PM Lisberger, the Chair of Neurobiology at Duke School of Medicine, emphasizes that while a single noisy neuron cannot produce an accurate estimate of speed and direction, the key lies in populations of neurons. On January 25, Lisberger presented his research to a diverse crowd of Duke scientists.

Lisberger and his team have performed multiple trials in which a monkey tracked a visual stimulus with his eye, thus activating certain neurons. They found that the noise persisted even in neural populations.

Lisberger, rather than being discouraged, turns this noise into an asset. He reasons that variation is something which the brain must handle; therefore, he can use variation to learn about the brain.

When a monkey follows a visual stimulus with his eye, he integrates the sensory system with a motor region of the brain called MT. Lisberger isolated the source of the noise to the sensory system, rather than MT. He found that other movements originating from MT did not display the same noise; thus, the noise in eye tracking must have come from the sensory system.

The noise from the sensory system propagates down to MT, and Lisberger follows in his analysis.

One of his colleagues proposed that the random noise over a large population of neurons should cancel itself out. Lisberger contradicts this idea, noting that the variation is correlated among neurons in MT. Variations in pairs of neurons fluctuate up and down together. Thus, some of the “noise” is actually signal. This shared noise is transmitted through the circuit, while independent noise averages itself away.

Ultimately, Lisberger models neural responses over multiple trials to statistically estimate the direction and speed indicated by a particular response. The brain though, has not the luxury of simultaneously integrating and analyzing such large pools of data in its fraction-of-a-second estimate. Instead, the brain makes do with what it has, which, as Lisberger points out, is enough.

By Olivia Zhu

Pace of Aging Story Makes Top Ten

By Karl Bates

On January 11, 2016

In Behavior/Psychology, Biology, Field Research, Genetics/Genomics, Guest Post

A study led by Center for Child and Family faculty fellows Daniel Belsky and Terrie Moffitt which found that some people grow old significantly faster than others, was named the No. 4 news story of 2015 by Science News.

The paper, published the week of July 6 in the Proceedings of the National Academy of Sciences, compared a panel of 18 biological measures that may be combined to determine whether people are aging faster or slower than their peers.

Dan Belsky

The data comes from the Dunedin Study, a landmark longitudinal study that has tracked more than a thousand people born in the same town between 1972-73. Health measures like blood pressure and liver function have been taken regularly, along with interviews and other assessments.

“We set out to measure aging in these relatively young people,” said first author Belsky, an assistant professor in the Department of Medicine. “Most studies of aging look at seniors, but if we want to be able to prevent age-related disease, we’re going to have to start studying aging in young people.”

Belsky said the progress of aging shows in human organs just as it does in eyes, joints and hair, but sooner. So, as part of their regular reassessment of the study population at age 38 in 2011, the team measured the functions of kidneys, liver, lungs, metabolic and immune systems. They also measured HDL cholesterol, cardiorespiratory fitness and the length of the telomeres—protective caps at the end of chromosomes that have been found to shorten with age.

Based on a subset of these biomarkers, the research team set a “biological age” for each participant, which ranged from under 30 to nearly 60 in the 38-year-olds.

According to Science News, “The finding tapped into a mystery that has long captivated scientists and the public alike…”

Where Memory Meets Imagination

By Karl Bates

On January 2, 2016

In Behavior/Psychology, Guest Post, Neuroscience

Imagine two scenarios. In the first, one of your close friends is driving down the road when, from behind, they hear the sound of wailing sirens. They pull off onto a sidestreet and ten minutes later they’re back on the road, holding a fresh speeding ticket. In the second, imagine the exact same scenario, but this time it’s not a close friend, it’s a random person who you know nothing about.

Felipe DeBrigard is an assistant professor of philosophy and a member of the Duke Institute for Brain Sciences. (Les Todd, Duke Photo)

This is the kind of scenario philosophy professor Felipe De Brigard might put someone through for his research. But while asking these questions, he would also be using an MRI machine to measure bloodflow in the brain and using the resulting data to think about philosophy.

De Brigard’s research is mostly concerned with this kind of thinking, the imagination of possibilities which never happened, but which could have happened. How many times have you wished you could change something about yourself? “Oh, if only I were two inches taller!?”

The way the brain does this, and what it means, are exactly what De Brigard is thinking about. For the example of speeding tickets, he’s found that in the first scenario, in which, your friend gets a ticket, the imagination activates parts of the brain which are also connected to autobiographical memory. It’s almost like you’re remembering something that happened to yourself.

But in the second scenario, the one with the stranger, he’s found something very different. The imagination activates parts of the brain which are connected to “semantic memory,” the memory of hard facts and data. This process is far more logical, he says.

What does this mean? That’s where the philosophy comes in. He says that memory is not a perfect window into the past, but instead “really good at allowing you to recall what could have been.”

The question which he’s asking now is how similar memory and imagination are and how they interact. It’s opening up new and exciting avenues for research. Research which can only be investigated using De Brigard’s bold, interdisciplinary approach to the mind.

Guest Post by Joe Wiswell, a senior at the North Carolina School of Science and Math

Middle Schoolers Ask: What's it Like to be a Scientist?

By Robin Smith

On December 16, 2015

In Animals, Behavior/Psychology, Biology, Chemistry, Environment/Sustainability, Physics, Science Communication & Education, Students

When a group of local middle schoolers asked four Duke postdocs what it’s like to be a scientist, the answers they got surprised them.

For toxicologist Laura Maurer, it means finding out if the tiny silver particles used to keep socks and running shirts from getting smelly might be harmful to your health.

For physics researcher Andres Aragoneses, it means using lasers to stop hackers and make telecommunications more secure.

And for evolutionary anthropologist Noah Snyder-Mackler, it means handling a lot of monkey poop.

The end result is a series of short video interviews filmed and edited by 5th-8th graders in Durham, North Carolina. Read more about the project and the people behind it at http://sites.duke.edu/pdocs/, or watch the videos below:

Five Duke Papers Crack the Altmetric 100

By Karl Bates

On December 14, 2015

In Animals, Behavior/Psychology, Biology, Medicine

The numbers are in, and five papers with Duke authors cracked the Top 100 Altmetric scores for 2015.

Example of an Altmetric analysis.

Yeah, it all seems a little gimmicky and meta, but the scores can be useful. Altmetric (to which Duke has an institutional membership) combines multiple counts of news stories, social media chatter and professional citations on an academic paper to give it a single score. Obviously, the system’s greatest strength is comparing this to other Altmetric scores, but it’s actually a lot of fun.

Duke’s biggest score – a very impressive Altmetric 2294 – came in at #5 on the list. “Estimating the reproducibility of psychological science” attracted a lot of attention in Science, spawning 74 news stories and nearly 2,000 tweets. Postdoctoral researcher Nina Strohminger of the Kenan Institute for Ethics is one of the authors from 125 institutions on the paper that suggests psychology has some housekeeping to do.

At number 28 with an Altmetric of 1,279, came “Global, regional and national incidence, prevalence, and years lived with disability for 301 acute and chronic diseases and injuries in 188 countries, 1990-2013 (here comes the colon!): a systematic analysis for the Global Burden of Disease Study 2013.” This Lancet paper, backed by the Bill and Melinda Gates Foundation, is every bit as massive and important as its title. Among its thousands of authors is our own Terrie Moffitt. It garnered 39 news stories and 1400 tweets and has already been incorporated into nine Wikipedia entries.

A companion paper with another big title for another big study, “Global, regional, and national age-sex specific all-cause and cause-specific mortality for 240 causes of death, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013,” came in at #36 on the list with an Altmetric of 1180. Its authors might be jealous of #28, but it’s mostly the same folks! Eighty people saw fit to post this one on Facebook and 60 on Google+.

Two papers out of the now-defunct NSF think-tank the National Evolutionary Synthesis Center (NESCent) rounded out our top 100 at #72 and #87.

What are the largest ocean giants?

Craig McClain of NESCent and Duke Biology led “Sizing Ocean Giants,” an analysis that tries to get the right dimensions on a bunch of intimidating ocean creatures including the giant clam and the colossal squid (which turns out to be only a third the size of the less impressively named giant squid). The paper’s Altmetric of 954 was led by 24 news stories, 24 blog posts and almost 900 tweets. McClain also leads a very popular marine science blog “Deep Sea News” which probably aided the story’s social presence.

Number 87 was “Synthesis of phylogeny and taxonomy into a comprehensive tree of life,” which included Karen Cranston of NESCent and Duke Biology. This hugely ambitious effort to draw a tree of life for the whole planet at once earned an Altmetric of 895 by garnering 21 news stories, 12 blogs and nearly 900 tweets. And it too has been incorporated into Wikimedia – once so far.

It’s a brave new world out there in academic publishing.

Post by Karl Leif Bates

Dam Good Research on Invasive Beavers in Patagonia

By Devin Nieusma

On December 11, 2015

In Animals, Behavior/Psychology, Biology, Environment/Sustainability, Field Research

Alejandro Pietrek and a subject of his research. Photo by Duke Forward.

For three years, Duke student Alejandro Pietrek has bravely grappled with some unusual marauders of the forests and steppes of Patagonia: invasive beavers. A biology graduate student, Pietrek recently presented his dissertation on the “Demography of invasive beavers in the heterogeneous landscapes of Patagonia.” Pietrek has studied over two dozen colonies of beavers in order to answer three questions:

“How do differences between habitats affect the demography of invaders?”
“How does density dependence affect the abundance and distribution of invaders post-establishment?”
“How can we manage biological invasions?”

Pietrek began by explaining how the furry rodents started ravaging the natural habitat of Patagonia, beginning with 20 beavers intentionally introduced into the forests of Tierra del Fuego in 1946. By the late 1960s, the growing colonies spread to the continent.

Today there are an estimated 100,000 individuals in Patagonia, disrupting the regional habitats and destroying biodiversity.

The biologist tackled his first question via quantitative science. “Very simply mathematical models have shown that speed of invasion is determined by two main things: population growth rate and movement,” he said. How the different habitats of Patagonia affected this invasion was what he worked to find out, by measuring colony size and the number of kits. Pietrek directly observed 25 colonies in each habitat over three years, using binoculars and seemingly endless patience. “It was very fun,” he said. He found that steppe habitats tended to have higher numbers of beavers and kits compared to forest.

Beaver Dam – Tierra del Fuego National Park, Argentina – Photograph by Anne Dirkse via Wikimedia Commons

Pietrek believed that the answer to the first question was counterintuitive, and he explored the possible reason in the second, where he figured the cause to be density dependence, as beavers in the steppe were more likely to survive in higher populations, and thus were dependent on living in large colonies for survival. In the forest, colony size wasn’t as important to the survival of the beavers. Pietrek found that as population density increased, the animals’ choice of landform changed: with denser numbers, the beavers were more likely to choose u-shaped valleys and plains than canyons. He noted the importance of identifying the preferred habitat of beavers, as it may allow easier detection of the presence of the invasive species.

Finally, Pietrek applied his findings toward the management of biological invasions. “One thing we can do is to build a model to predict the spread of beavers,” he said. He observed that beavers spread on average 7.8 km per year, though he also used individual-based models as well in order to track juvenile beavers. He found that young beavers tended to disperse and form new colonies, and formed another model in order to track this dispersal pattern. Juvenile beavers will first search for mates within their original colonies, only moving along if none can be found. These findings make for easier tracking of beavers across the landscape, allowing for easier management of their population growth.

Post by Devin Nieusma, Duke 2019

Science a waste of money? “Wastebook” misses big picture

By Robin Smith

On December 7, 2015

In Animals, Behavior/Psychology, Biology, Engineering, Faculty, Science Communication & Education

Duke biologist Sheila Patek explains the big picture behind a recent study on sparring mantis shrimp. Photograph by Roy Caldwell.

Sheep in microgravity. An experiment involving a monkey in a hamster ball on treadmill. These are among more than 100 descriptions of what Senator Jeff Flake, Republican of Arizona, deems wasteful federal spending in “Wastebook: The Farce Awakens,” released on Tuesday, Dec. 8. The latest in a series originally launched by retired Senator Tom Coburn, each “Wastebook” targets a range of federally-funded projects, many of them science-related, which the authors declare a waste of taxpayers’ money.

But what do the researchers behind these projects have to say? We asked Duke biologist Sheila Patek, whose work on fighting mantis shrimp was singled out in Flake’s latest report, to tell us her side of the story:

“What do we stand to learn from basic research on mantis shrimp? It turns out, a lot,” Patek said.

“First, mantis shrimp strike with weapons operating at the same acceleration as a bullet in the muzzle of a gun, yet they achieve high performance without explosive materials. They use a system based on muscles, springs and latches and neutralize their opponents with impact-resistant armor. This research helps us understand how animals survive when they have lethal weapons at their disposal but do not actually kill the opponent — something that could change the way we look at future defense systems,” Patek said.

“Second, these crustaceans have properties of extreme acceleration that are of great interest to military and manufacturing engineers. Mantis shrimp use a toothpick-sized hammer that can break snail shells in water that humans can only break with a larger hammer in air. Their small, lightweight hammer resists fracture over thousands of uses. Our research has already led to the development of novel engineered materials that resist impact fracture, based directly on mantis shrimp hammers,” Patek said.

“Third, mantis shrimp do something else that humans cannot: strike in water at the speed of cars on a major highway without causing cavitation, a phenomenon that occurs in systems with rapid motion (like propellers) where implosive bubbles emit heat, light and sound with energy sufficient to wear away steel. Naval engineers have been trying to solve this problem since the invention of the submarine. When we understand how mantis shrimp avoid cavitation during the rotation phase of their strikes while effectively using cavitation during their impact phase, the knowledge will undoubtedly improve the capabilities of ships, submarines, torpedoes and other machines,” Patek said.

“Research that helps us understand and apply the mechanics and evolutionary diversity of natural systems to create a better and safer society for all of us is a wise investment for this country.”

Post by Robin A. Smith, Senior Science Writer

The dangerous persistence of smoking into the 21st century

By Thabit Pulak

On November 16, 2015

In Behavior/Psychology, Lecture, Medicine

The “smoking ring” cigarette billboard advertisement in New York City. Picture Credit: theoldmotor.com

When Harvard historian of science Allan Brandt was a child, he couldn’t help but notice one thing in particular when in the car with his family — the cigarette advertising billboards. At the time, there was a very unique billboard that advertised Camel cigarettes, which actually smoked “rings” from the board. His young mind was captivated by how cool the board looked — and presumably, unaware of the dangers of the product the board was advertising.

As time passed, it became increasingly clear to Brandt and to the American public that smoking cigarettes was bad for you. Brandt’s most recent book – The Cigarette Century, was awarded the Bancroft Prize in 2008. In Brandt’s words, cigarettes are the “most dangerous product ever produced in such large quantities.” And indeed, the numbers are shocking — over 480,000 Americans die annually of tobacco-related diseases.

Given such obvious problems associated with cigarettes, Brandt started wondering, “How could something so bad for you be so advertised in such bold ways?”

The answer, Brandt explained to a Duke audience gathered on Nov. 11 for the 2015 Boyarsky Lecture in Law, Medicine and Ethics, was manipulation — the American public was being grossly manipulated by the bold advertising of cigarettes. Brandt talked about Mr. Edward Bernays, who, according to Brandt, is one of the main founders of the concept of modern public relations, made extensive efforts to put smoking into the mainstream media. One of Bernays’ biggest achievements was the widespread introduction of smoking to Hollywood. The efforts to introduce smoking to mainstream media worked amazingly well. By the mid-1950s, nearly half of all Americans were smoking. To put this into perspective, at the turn of the 20^th century, nearly no Americans were smoking!

However, as more and more research proved that cigarettes were actually harmful to Americans’ health, another curious phenomenon happened, where cigarette companies were actually funding their own research.

Brandt pointed out how this was a thinly disguised attempt to publish misleading conclusions about cigarettes to the public by establishing it as “science.” Such biased research funding occurs today in other industries as well, such as for oil companies, for research concerning climate change.

Children smoking in various developing countries is not uncommon, and poses a huge health risk to them. Picture Credit: CBSNews

However, public health campaigns still showed measurable positive impact — today it is evident that there is a declining trend in the number of smokers in America. However, wouldn’t that mean that the cigarette industry would die down? According to Brandt, it couldn’t be farther from the truth. The cigarette industries have now moved to exporting cigarettes to the developing world, where populations are less educated, and there are fewer regulations concerning such sales.

According to Brandt, in 2000, four million people died — two million died in the developed world, and two million in the developing world. By the year 2030, over 10 million people total will be killed by cigarette use — three million in developed nations, and seven million in developing nations. The rapid proliferation in such developing countries due to lack of education and awareness is heavily evident, especially with the much higher rate of childhood smoking. It is heavily evident that most of the disease fatalities will be borne by developing nations in the coming years, and will ensure copious profits for cigarette companies for years to come.

While Brandt did acknowledge the very persistent growth of the cigarette companies in the near future, he did not rule out that it was still possible to fight against this. By working together, we can all help bring awareness to the parts of the world where cigarettes are being advertised to uneducated people.

Post by Thabit Pulak, Duke 2018

Iridescent Beauty: Development, function and evolution of plant nanostructures that influence animal behavior

By Anika Radiya-Dixit

On October 27, 2015

In Animals, Behavior/Psychology, Biology, Chemistry, Field Research, Genetics/Genomics

Iridescent wings of a Morpho butterfly

Creatures like the Morpho butterfly on the leaf above appear to be covered in shimmering blue and green metallic colors. This phenomenon is called “iridescence,” meaning that color appears to change as the angle changes, much like soap bubbles and sea shells.

Iridescent behavior of a soap bubble

In animals, the physical mechanisms and function of structural color have been studied significantly as a signal for recognition or mate choice.

On the other hand, Beverley Glover believes that such shimmering in plants can actually influence animal behavior by attracting pollinators better than their non-iridescent counterparts. Glover,Director of Cambridge University Botanic Garden, presented her study during the Biology Seminar Series in the French Family Science Center on Monday earlier this week.

Hibiscus Trionum

The metallic property of flowers like the Hibiscus Trionum above are generated by diffraction grating – similar to the way CD shines – to create color from transparent material.

In order to observe the effects of the iridescence on pollinators like bees, Glover created artificial materials with a surface structure of nanoscale ridges, similar to the microscopic view of a petal’s epidermal surface below.

Nanoscale ridges on a petal’s epidermal surface.

In the first set of experiments, Glover and her team marked bees with paint to follow their behavior as they set the insects to explore iridescent flowers. Some were covered in a red grating – containing a sweet solution as a reward – and others with a blue iridescent grating – containing a sour solution as deterrent. The experiment demonstrated that the bees were able to detect the iridescent signal produced by the petal’s nanoridges, and – as a result – correctly identified the rewarding flowers.

Bees pollinating iridescent “flowers”

With the evidence that the bees were able to see iridescence, Glover set out for the second experiment: once the bees find a specific type of flower, how long does it take them to find the same flower in a different location? Using the triangular arrangement of shimmering surfaces as shown below, Glover observed that iridescence produced by a diffraction grating leads to significant increase in foraging speed as compared to non-iridescent flowers.

Triangular formation of iridescent disks used for experimentation on bees

While iridescence in plants is difficult to spot by a casual stroll through the garden, pollinators such as bees definitely can see it, and scientists have recently realized that insect vision and flower colors have co-evolved.

In order to ensure that pollen is transferred between flowers of the same species, these flowers have developed a unique structure of iridescence. As scientists work on understanding which plants produce these beautiful colors and how the nanoscale structure is passed down through reproduction, we can only look at our gardens in wonder at the vast amount of nature that still remains to be explored and learned.

Wonders of nature in an everyday garden

Beverley Glover is the Director of Cambridge University Botanic Garden and is currently accepting applications for PhD students.

Post written by Anika Radiya-Dixit

Moving Beyond #DistractinglySexy

By Olivia Zhu

On October 26, 2015

In Behavior/Psychology, Faculty, Students

Let’s not talk about Tim Hunt.

(Okay, a little: He’s the Nobel laureate who told the World Conference of Science Journalists, “Let me tell you about my trouble with girls. Three things happen when they are in the lab: you fall in love with them, they fall in love with you, and when you criticize them, they cry.”)

Instead, let’s talk about the invisible sexism and gender inequality pervasive in graduate school and industry, emphasized the panelists for the Graduate Women in Science’s Fall Career Development Panel, and let’s figure out how to effect meaningful change in the workplace.

Dr. Bruce, Dr. Reiskind, and Dr. Bickford, from left to right

On October 20, Dr. Donna Bickford, Associate Director of the Office of Undergraduate Research at UNC, Dr. Katherine Bruce, Assistant Professor at Salem College, and Dr. Martha Reiskind, Research Assistant Professor at NC State, hosted an honest conversation about microaggressions, social gender norms, and general advice for dealing with a hostile work environment.

Though the panelists and the attending graduate students were loath to talk about one individual’s aggression, they looked incredibly favorably upon the social media movement, #DistractinglySexy, which resulted from Hunt’s comments.

The hashtag movement declares that, “You can be feminine, and you can be a scientist,” said Dr. Bruce, a sociologist. It breaks from reactionary notions that women must adopt masculine behavior in order to excel in their professions, as well as fosters a larger support community for women who may often feel isolated as the only female in their lab.

The biggest disappointment of the #DistractinglySexy campaign though, was the lack of genuine conversation that followed. Dr. Bickford, an English professor, said that many men agreed with the sentiment of the movement but dismissed further concerns of daily sexism in the workplace, citing men like Hunt as anomalies and the sole perpetrators: “There are a few dinosaurs, but they’re dying.”

The panelists addressed the difficult question of how a woman ought to stand up to offending men in the workplace. “You’re damned if you do and damned if you don’t… How do you blow the whistle without being betrayed?” asked Dr. Reiskind, who addresses issues of sexism in her lab. Especially in situations where the perpetrator is in a position of power, calling out sexist behavior carries the risk of being perceived as a “baying witch,” while remaining silent condemns one to perpetual harassment.

On the question of inaction from women, Dr. Reiskind described the utter disbelief, echoed by the other panelists, that often strikes when assault or harassment has occurred– the bizarre nature of the situation may prevent women from speaking up in the immediate moment where action may be conducive to behavior remediation.

Ultimately, this panel set out to solve problems. While no legislation was passed or cases resolved, holding honest, open conversations to more deeply understand issues is the first step in creating gender-equal workplaces.

By Olivia Zhu, Duke 2016