Tuesday, September 22, 2020

'Firefly' method makes cellular forces visible at molecular scale

The image on the left shows the force activity of a cell at a resolution of about 250 nanometers. The image on the right shows how much clearer the image becomes with the resolution of 25 nanometers that is now possible with the new technique. (Microscopy photos by Alisina Bazrafshan)

Scientists have developed a new technique using tools made of luminescent DNA, lit up like fireflies, to visualize the mechanical forces of cells at the molecular level. Nature Methods published the work, led by chemists at Emory University, who demonstrated their technique on human blood platelets in laboratory experiments.

"Normally, an optical microscope cannot produce images that resolve objects smaller than the length of a light wave, which is about 500 nanometers," says Khalid Salaita, Emory professor of chemistry and senior author of the study. "We found a way to leverage recent advances in optical imaging along with our molecular DNA sensors to capture forces at 25 nanometers. That resolution is akin to being on the moon and seeing the ripples caused by raindrops hitting the surface of a lake on Earth."

Almost every biological process involves a mechanical component, from cell division to blood clotting to an immune response. "Understanding how cells apply forces and sense forces may help in the development of new therapies for many different disorders," says Salaita, whose lab is a leader in devising ways to image and map bio-mechanical forces.

The first authors of the paper, Joshua Brockman and Hanquan Su, did the work as Emory graduate students in the lab. Both recently received their PhDs.

Read the full story here.

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Thursday, September 10, 2020

Experiments reveal why human-like robots elicit uncanny feelings

"At the core of this research is what we perceive when we look at a face," says Emory psychologist Philippe Rochat, senior author of the study. (Getty Images)

By Carol Clark

Androids, or robots with humanlike features, are often more appealing to people than those that resemble machines — but only up to a certain point. Many people experience an uneasy feeling in response to robots that are nearly lifelike, and yet somehow not quite “right.” The feeling of affinity can plunge into one of repulsion as a robot’s human likeness increases, a zone known as “the uncanny valley.”

The journal Perception published new insights by Emory psychologists into the cognitive mechanisms underlying this phenomenon.  

 

Since the uncanny valley was first described, a common hypothesis developed to explain it. Known as the mind-perception theory, it proposes that when people see a robot with human-like features, they automatically add a mind to it. A growing sense that a machine appears to have a mind leads to the creepy feeling, according to this theory.

 

“We found that the opposite is true,” says Wang Shensheng, first author of the new study, who did the work as a graduate student at Emory and recently received his PhD in psychology. “It’s not the first step of attributing a mind to an android but the next step of ‘dehumanizing’ it by subtracting the idea of it having a mind that leads to the uncanny valley. Instead of just a one-shot process, it’s a dynamic one.”

 

The findings have implications for both the design of robots and for understanding how we perceive one another as humans.

 

“Robots are increasingly entering the social domain for everything from education to healthcare,” Wang says. “How we perceive them and relate to them is important both from the standpoint of engineers and psychologists.”

 

“At the core of this research is the question of what we perceive when we look at a face,” adds Philippe Rochat, Emory professor of psychology and senior author of the study. “It’s probably one of the most important questions in psychology. The ability to perceive the minds of others is the foundation of human relationships. ”

 

The research may help in unraveling the mechanisms involved in mind-blindness — the inability to distinguish between humans and machines — such as in cases of extreme autism or some psychotic disorders, Rochat says.

 

Co-authors of the study include Yuk Fai Cheong and Daniel Dilks, both associate professors of psychology at Emory.

 

Anthropomorphizing, or projecting human qualities onto objects, is common. “We often see faces in a cloud for instance,” Wang says. “We also sometimes anthropomorphize machines that we’re trying to understand, like our cars or a computer.”

 

Naming one’s car or imagining that a cloud is an animated being, however, is not normally associated with an uncanny feeling, Wang notes. That led him to hypothesize that something other than just anthropomorphizing may occur when viewing an android.

 

To tease apart the potential roles of mind-perception and dehumanization in the uncanny valley phenomenon the researchers conducted experiments focused on the temporal dynamics of the process. Participants were shown three types of images — human faces, mechanical-looking robot faces and android faces that closely resembled humans — and asked to rate each for perceived animacy or “aliveness.” The exposure times of the images were systematically manipulated, within milliseconds, as the participants rated their animacy.

 

The results showed that perceived animacy decreased significantly as a function of exposure time for android faces but not for mechanical-looking robot or human faces. And in android faces, the perceived animacy drops at between 100 and 500 milliseconds of viewing time. That timing is consistent with previous research showing that people begin to distinguish between human and artificial faces around 400 milliseconds after stimulus onset.

 

A second set of experiments manipulated both the exposure time and the amount of detail in the images, ranging from a minimal sketch of the features to a fully blurred image. The results showed that removing details from the images of the android faces decreased the perceived animacy along with the perceived uncanniness.

 

“The whole process is complicated but it happens within the blink of an eye,” Wang says. “Our results suggest that at first sight we anthropomorphize an android, but within milliseconds we detect deviations and dehumanize it. And that drop in perceived animacy likely contributes to the uncanny feeling.”


Related:

Schadenfreude sheds light on the darker side of humanity

How babies see faces


 

Tuesday, August 18, 2020

Study shows how a single gene drives aggression in wild songbirds

White-throated sparrows come in two different morphs, the white-striped (left) and the tan-striped (right). The morphs have both different plumage and behaviors, making these wild songbirds a good model organism for the genetic basis of behavior. (Photo by Jennifer Merritt)

By Carol Clark

A new study shows how differentiation of a single gene changes behavior in a wild songbird, determining whether the white-throated sparrow displays more, or less, aggression. The Proceedings of the National Academy of Sciences (PNAS) published the research, led by neuroscientists at Emory University.

The researchers singled out an estrogen receptor from a complex of more than 1,000 genes known as a “supergene,” or genetic material inherited together as a block. The work provides a rare look at how genomic divergence can lead to behavioral divergence in a vertebrate.

“Evolution has tinkered with the DNA sequence of a gene of this songbird, and we demonstrated that those little changes affect both the expression of the gene and the bird’s behavior,” says Emory graduate student Jennifer Merritt, first author of the paper.

Merritt is a PhD candidate in the lab of Donna Maney, senior author of the paper and an Emory professor of psychology.

“White-throated sparrows are common backyard birds found through most of North America,” Merritt says. “What’s remarkable about them is that they occur in two different morphs that have not only different plumage, but also different strategies for maximizing reproductive output. Both types of differences are caused by genetic differentiation of only one region of a single chromosome, and we know exactly where it is.”

At some point during the evolution of a species, a chromosome can break and flip. This process, called an inversion, isolates the genes that are trapped inside, producing a supergene. In some cases, supergenes have led to distinct morphs within a single species — individuals with the supergene and those without it.

In the case of the white-throated sparrows, the white-striped morph sports bright yellow, black and white stripes on its crown while the tan-striped morph has more muted, tan and grayish stripes. The white-striped birds, which all possess at least one copy of the rearranged chromosome, tend to be more aggressive and less parental than the tan-striped birds, which do not have the rearranged chromosome.

“Scientists have hypothesized for 100 years that inversions are important for the evolution of some of the complex behaviors that we see in nature,” Maney says. “But inversions are challenging to understand because, when they turn into supergenes, all of the genes are inherited together. We already knew a lot about the natural history of the white-throated sparrow, as well as the biological mechanisms underlying its aggression. Using that knowledge, we were able to finally show the evolutionary role of a supergene at the molecular level.”

The current paper builds on previous work by the Maney lab, a leader in connecting gene sequence with behavior in free-living animals. In 2014, the lab identified a hormone receptor —estrogen receptor alpha (ER-alpha) — that appeared connected to the differences in the sparrows’ aggression and parenting behaviors in the wild. The white-striped birds express this receptor at much higher levels than the tan-striped birds, and the more the expression, the more aggressive the bird.

“For this paper, we wanted to follow the genetic variation of ER-alpha all the way up to where it’s expressed in the brain, and then to behavior, to see if we could trace the behavioral variation to variation in this one gene,” Merritt says.

The birds sing to establish a territory. The rate at which they sing gives a measure of their level of aggression, along with the frequency at which they charge, or “attack,” animals encroaching on what they consider their territory.

In field studies of white-throated sparrows in their natural habitat, the researchers showed that the more a bird expresses the supergene version of the estrogen receptor, the more vigorously it defends its territory.

The researchers then moved beyond the correlational work by taking an experimental approach. White-throated sparrows in the lab were given a substance to block expression of the ER-alpha gene and their aggression levels were measured. The results showed that when expression of that one gene was blocked, the aggression of the white-striped birds went down so they behaved like the tan-striped ones.

“We believe this is the first demonstration of how a single gene within a supergene drives changes in a social behavior in a wild vertebrate,” Merritt says. She gives an analogy for the challenge involved: “Imagine each of the genes within a supergene as tributaries converging into a river, the behavior. And then taking a sample of water from the river and determining which tributary the sample came from.”

The Maney lab is continuing to investigate a suite of other neuroendocrine genes captured by the chromosome rearrangement in the white-throated sparrow that are thought to be important players in the regulation of social behavior.

Co-authors of the PNAS paper include Eric Ortlund, a biochemist and an expert in the ER-alpha gene at the Emory School of Medicine; Kathleen Grogan and Wendy Zinzow-Kramer, former post-doctoral fellows in the Maney lab; and Dan Sun and Soojin Yi, from Georgia Tech. The work was funded by grants from the National Institutes of Health and the National Science Foundation.

Related:
Wild sparrow study traces social behaviors in the wild to a single gene
Birdsongs study pecks theory that music is uniquely human

Friday, August 7, 2020

Emory students win Amazon's Alexa Prize for AI with strategy of caring about others

Jinho Choi (center), the faculty advisor for the Emory Alexa Prize team, with graduate students James Finch (left), and Sarah Fillwock, the team leader.

A team of Emory University students won Amazon’s 2020 Alexa Prize, a global competition to create the most engaging chatbot to advance the field of artificial intelligence. The team earned $500,000 for taking first place with their chatbot named Emora.

The students designed Emora to provide comfort and warmth to people interacting with Amazon’s voice-activated Alexa-enabled devices, whether they wanted to discuss movies, sports and their pets or their concerns for themselves and their families amid the COVID-19 pandemic.

The Emory team consisted of 14 students led by graduate student Sarah Fillwock and faculty advisor Jinho Choi, assistant professor in the Department of Computer Science. They christened their chatbot Emora because it sounds like a feminine version of “Emory” and is similar to a Hebrew term for a sage skilled in eloquence.

Even as they celebrate their win, the Emory team is looking ahead to how they can apply the concepts they developed to benefit everything from education to people suffering from depression and social isolation.

The annual Alexa Prize, launched in 2016, challenges university students to make breakthroughs in the design of chatbots, or social bots — software apps that simplify interactions between humans and computers by allowing them to talk with one another. Emory used a unique strategy to beat out nine other universities and take the top spot in this year’s competition, the most hotly contested ever. 

“Normally people think of a chatbot as being an intelligent assistant, to answer questions or provide a customer service,” Fillwock says. “We designed a more socially oriented chatbot that could actually show interest in an individual user and provide comfort to people if they wanted it.”

Read the full story.

Related:
Emory team vies for best social bot via Amazon's Alexa Prize

Wednesday, July 29, 2020

Butterfly genomics: Monarchs fly differently, but meet up and mate

An eastern monarch butterfly rests in Saint Marks, Florida, on its way to overwinter in Mexico. (Photo by Venkat Talla)

Each year, millions of monarch butterflies migrate across eastern North America to fly from as far north as the U.S.-Canadian border to overwinter in central Mexico — covering as much as 3,000 miles. Meanwhile, on the other side of the Rocky Mountains, western monarchs generally fly 300 miles down to the Pacific Coast to spend the winter in California. It was long believed that the eastern and western monarchs were genetically distinct populations.

A new study, however, confirms that while the eastern and western butterflies fly differently, they are genetically the same. The journal Molecular Ecology published the findings, led by evolutionary biologists at Emory University.

“It was surprising,” says Jaap de Roode, Emory professor of biology and senior author of the study. His lab is one of a handful in the world that studies monarch butterflies.

“You would expect that organisms with different behaviors and ecologies would show some genetic differences,” de Roode says. “But we found that you cannot distinguish genetically between the western and eastern butterflies.”

Read the whole story here.

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Mystery of monarch migration takes new turn
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