A new view of how the brain decides to make an effort

"The willingness to expend effort is something crucial to our survival that we use every day," says Emory psychologist Michael Treadway, senior author of the study.

Neuroscientists have provided clear visual evidence that a region of the human brain known as the ventral striatum kicks in during decision-making to weigh the costs versus the benefits of making a physical effort. 

Nature Human Behavior published the research by scientists at Emory University. It gives the first detailed view of ventral striatum activity during three phases of effort-based decision-making — the anticipation of initiating an effort, the actual execution of the effort and the reward, or outcome, of the effort. 

“It’s important to understand the neural mechanisms underlying motivation,” says Shosuke Suzuki, first author of the study and an Emory graduate student of psychology. “Our work has wide implications for treatment of disorders related to reduced motivation, such as depression, schizophrenia and PTSD. It may also help enhance motivational programs for everything from education to athletics and public health.”

Click here to read the full story.

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Valuing 'natural capital' vital to avoid next pandemic, global experts warn

Every economic decision needs to take natural capital into account to avoid an even bigger catastrophe than the current pandemic, says Emory disease ecologist Thomas Gillespie.

By Carol Clark

Pandemics will emerge more often, kill more people than COVID-19 and do even more damage to the world economy unless urgent steps are taken to address risk drivers such as deforestation, warns a major new report on biodiversity and pandemics. 

The report, entitled “Escaping the Era of Pandemics,” was made public by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), which includes United Nations members from more than 100 governments. The report is the result of an urgent workshop organized by the IPBES. The workshop brought together 22 experts to evaluate scientific evidence and make recommendations to control and prevent future pandemics, detailed in the report, which IPBES members will now consider whether to endorse. 

“The two biggest driving forces for pandemics are forest degradation and industrial animal production,” says Thomas Gillespie, an associate professor in Emory’s Department of Environmental Sciences and Rollins School of Public Health, who served as a scientific peer reviewer for the report. “Greater management and surveillance of wet markets, where live animals are sold, is also important.” 

Every major economic decision, Gillespie warns, needs to take into account what he calls “natural capital” in order to avoid even bigger catastrophes than the current pandemic. 

The economic costs of a major pandemic are 100 times the estimated costs of prevention, the report notes. It recommends government policy changes to reduce globalized agricultural expansion and the types of trade that have led to pandemics. Some of the possible measures it cites are taxing meat consumption and livestock production and reforming financial aid for land use to consider risks to biodiversity and health. 

Like all pandemics, the emergence of the novel coronavirus was driven entirely by human activities, the report states. The authors estimate that another 1.7 million currently “undiscovered” viruses exist in mammals and birds — and nearly half of them may have the potential to infect people. 

National governments need to incorporate a “One Health” approach — considering the deep connections between the health of people, domesticated animals, wildlife and ecosystems — to build pandemic control and prevention efforts, the report adds. 

Thomas Gillespie in 2018 with famed primatologist Jane Goodall. He is working with the Jane Goodall Institute on a One Health project in Tanzania's Gombe National Park.

Gillespie is a disease ecologist who helped pioneer the “One Health” approach to protect humans, ecosystems and biodiversity. His projects in Africa, including collaborating with Jane Goodall at Gombe National Park in Tanzania, are focused on helping farmers subsisting amid fragmented forests co-exist with primates and other wildlife in ways that minimize the risk of pathogen exchange between species, known as “spillover.” HIV, for instance, spilled over from chimpanzees to humans. Infectious disease and deforestation are the two biggest challenges facing chimpanzees at Gombe today, according to a newly published study led by Goodall and co-authored by Gillespie. 

The Gillespie Lab has a similar project in Costa Rica, focused on bats in fragmented natural ecosystems.

Now, Gillespie finds himself virtually managing his lab’s field projects while also advising global policymakers. “More people are listening,” Gillespie says. “This pandemic has fueled awareness that a One Health approach applied on a grand scale is vital to both local and global economies.” 

In the following Q&A, Gillespie explains the seismic shifts he says are needed to protect global health and economies against the impacts of pandemics. 

What do you mean exactly by “natural capital”? 

Natural capital consists of ecosystems of nature that sustain us. Human activity has driven an overall global decline in natural resources of 40 percent per capita in just over 20 years. Our economies, our health and our well-being are all built upon natural capital. 

There is growing recognition that we are totally dependent on the natural capital of our planet and that perpetual economic growth is not sustainable. We’ve had a false sense that we can simply measure the success of countries and policies through gross domestic product and economic growth, even when it means we are taking loans from nature that we have no capacity to repay. 

The rising risks of pandemics has caught the attention of people who are in charge of economies because COVID-19 is immediately affecting bottom lines. Every country is feeling the pain simultaneously, at both individual and national levels. 

Is it possible for human development and conservation to co-exist? 

When people talk about development from an economic standpoint it involves conversion of natural resources for profit, often by degradation of ecosystems via mining, timber cutting, oil extraction or clearing for cash crops. But when we talk about development from a sustainability perspective, we’re talking about improving the quality of human life. 

Use of the word “development” in these different ways can lead to a great deal of confusion. The urgency of the coronavirus pandemic is helping to break the silos down so that people from both camps can come together to think about solutions. There is growing recognition that instead of just considering whether a land-use project will impact a certain endangered species, we need to have mechanisms to evaluate more broadly how projects may impact the health of wildlife, people and an entire ecosystem. 

Right now, those profiting from economic development are not the ones paying the costs. The data shows very clearly that you can have a high GDP (gross domestic product) and also have plenty of poor people and a large proportion of a population struggling to survive. There is not a clear linkage between gains in the stock market and the quality of life for the average citizen. 

How does climate change fit into this “One Health” approach? 

Although many have rallied behind mitigating and adapting to climate change, it’s just one of the troubling vital signs of the planet. Climate change, biodiversity loss and the ever-increasing risks of pandemics are all symptoms of the same illness — our disconnect with nature and associated unsustainable norms. 

We’ve long needed to bring together climate scientists, disease ecologists and policymakers from agriculture, financial and environmental systems to tackle the illness instead of just having them all separately focus on individual symptoms. This shift is occurring, discussions are happening. The challenges are enormous, but at least now everyone has come together at the same table to try to work toward solutions. 

What are some examples of individual countries taking on these challenges? 

U.S. President-elect Joe Biden has vowed to rejoin the Paris Agreement for carbon reductions and set a 2050 carbon neutrality target. That holds huge implications for global climate diplomacy and will also create opportunities to rally behind shared solutions to prevent future pandemics and to safeguard the planet’s ecosystem services upon which our collective future depends. 

Some governments are beginning to remove environmentally harmful subsidies and redirecting incentives for a green recovery. In fact, New Zealand, Scotland and Iceland are recasting their entire economic frameworks to officially prioritize human well-being and planetary health over GDP. 

New Zealand developed a “Living Standards Framework” to set its budget. Bhutan now shapes policy to advance what it calls its “Gross Happiness Indicator.” Similarly, the world’s largest sovereign wealth fund — the Norwegian Government Pension Fund — has divested from 32 companies involved in unsustainable palm oil production. 

These kinds of initiatives are leading the way to build a better future together.

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Major review of plants' role in antibacterial activity clears new paths for drug discovery

"If ever there was a time to cultivate our knowledge and tap into the chemical power of plants, this is it," says ethnobotanist Cassandra Quave, noting that two in five plants are currently estimated to be threatened with extinction as a result of destruction of the natural world. (Getty Images)

By Carol Clark

Scientists have compiled the first comprehensive review of plant natural products that play a role in antibacterial activity, to serve as a guide in the search for new drugs to combat antibiotic-resistant pathogens. 

Chemical Reviews published the work by researchers at Emory University, which includes 459 plant natural products that met rigorous criteria for demonstrating antibacterial activity. The review is also deposited on the Shared Platform for Antibiotic Research and Knowledge (SPARK), sponsored by Pew Charitable Trusts. 

“We hope that chemists and pharmacology researchers will use our review as a guide to dig deeper into the promising potential of many plant compounds,” says Cassandra Quave, senior author of the review and associate professor in Emory’s Center for the Study of Human Health and Emory School of Medicine’s Department of Dermatology. Quave is also a member of the Emory Antibiotic Resistance Center. 

In the United States, at least 2.8 million people get antibiotic-resistant infections each year and more than 35,000 people die from them, according to the Centers for Disease Control and Prevention. 

“If ever there was a time to cultivate our knowledge and tap into the chemical power of plants, this is it,” Quave says. “We’re seeing a rise in antimicrobial resistance across the globe. And, at the same time, we’re also losing vast amounts of plant biodiversity.” 

Two in five plants are currently estimated to be threatened with extinction, according to the State of the World’s Plants and Fungi Report, published in 2020 by the Royal Botanic Gardens, Kew. 

Quave is a leader in the field of medical ethnobotany, studying how Indigenous people incorporate plants in healing practices to uncover promising candidates for new drugs. The Quave lab has identified compounds from plants such as the Brazilian peppertree, the American beautyberry and the European chestnut that inhibit dangerous antibiotic-resistant bacteria. Her lab found, for instance, that triterpenoid acids from the Brazilian peppertree “disarm” methicillin-resistant Staphylococcus aureus, known as MRSA, by blocking its ability to produce toxins. 

The first antibiotic, penicillin, was derived from microbes in mold that kill bacteria. Since then, scientists have found other microorganisms that live in soil that are easy to grow in a laboratory setting and can kill pathogens resistant to some drugs. The ability of bacteria to continue to evolve resistance, however, is outpacing the ability to generate effective drugs from these sources. 

“One obstacle to plant natural products making it into the new drug pipeline is the complexity of the discovery process,” Quave says. “You have to identify a promising plant candidate, tease through the hundreds of chemicals contained within a particular plant to identify the active compound, and then isolate enough of this compound to do experiments on it. It’s not nearly as easy as sequencing a soil microbe and growing up a big vat of it to conduct experiments.” 

Tapping the knowledge of traditional people who have used plants for centuries to treat infections offers valuable clues for where to focus research, she adds. 

“In recent decades, interest has grown in investigating plants as potential drug candidates,” Quave says. “Technologies have improved to more easily access and study bioactive molecules within plants. And more papers are being published that follow standardized procedures for evaluation of antimicrobial activities among plant compounds.” 

For the current review, the Quave lab looked at nearly 200 papers published between 2012 and 2019 that met strict standardization criteria for authenticating plant-derived compounds that significantly inhibited antibacterial activity. The co-authors spanned undergraduates who conducted the initial literature reviews to graduate students and scientists specialized in biology, chemistry, pharmacology and/or botany. 

The 459 compounds included in the review encompass a diverse range of species — including those from commonly known plant families such as citrus, daisies, beans and mint. The compounds fall into three major classes of chemicals: About half are phenolic derivatives, around 25 percent are terpenoids, nearly 6 percent are alkaloids and the remainder are classified as other metabolites. 

The co-authors selected 183 of the compounds and provided further discussion of their antibacterial activity, biosynthesis, chemical structure, mechanism of action and their potential as antibiotics. 

“These are all compounds as they appear in nature, not synthesized or derivatized by chemists,” Quave explains. “We wanted to provide a systematic overview that brings promising drug candidates to the forefront, opening up new chemical space for discovery. Our review can serve as a starting point for chemists to consider whether they could possibly optimize any of these compounds to become scaffolds for antibiotic treatments.” 

Co-authors of the review include the following members of the Quave lab: Gina Porras, a post-doctoral fellow specialized in natural products chemistry; François Chassagne, a post-doctoral fellow and a pharmacologist; James Lyles, an associate academic research scientist and analytical chemist; Lewis Marquez, a graduate student of pharmacology; Micah Dettweiler, a former research specialist in the lab who is now a graduate student in agronomy at the University of Florida; Akram Salam, a graduate student of pharmacology; Tharanga Samarakoon, a botanist and collections manager of the Emory University Herbarium; Sarah Shabih, an Emory senior majoring in human health; and Darya Farrokhi, who graduated from Emory in 2020 with a degree in biology. 

The work was supported by the National Institute of Allergy and Infectious Disease, the National Center for Complementary and Integrative Health, Emory University and The Jones Center at Ichauway in Georgia.

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Taking math by storm: Talea Mayo models how climate change may affect our coasts

"I use a computer to solve math problems surrounding the way that fluid moves during storms," says Emory mathematician Talea Mayo. "I don't study the atmosphere. I study the response of the ocean to the atmosphere."

By Carol Clark

Talea Mayo joined the Emory faculty in May as assistant professor in the Department of Mathematics. A computational mathematician, she specializes in developing numerical hydrodynamic models to help predict coastal hazards.  

By creating models for storm surge caused by hurricanes, for instance, she is able to investigate the potential impacts of climate change on coastal flood risks. The resulting data may help policymakers and others develop better plans for the safety and resilience of coastal communities. 

Among Mayo’s accolades are an Early-Career Research Fellowship from the National Academies of Sciences Gulf Research Program and the Early Career Faculty Innovator Award from the National Center for Atmospheric Research. 

In the following Q&A, Mayo talks about some of the environmental forces that helped shape her as a scientist and as an educator, and how she became what she describes as “a fierce advocate of accessible, inclusive science and education of all people.” 

You grew up in Littleton, Colorado. What were some of your early math and computer science influences? 

My mom was in software development and we always had a computer around. I don’t ever remember not having one nearby. Before I even started school, she bought me this really simple kid’s learning tool that was like a computer, with a keyboard and a screen. By the time I was in first grade, she was teaching me multiplication and I would practice on my “computer.” 

I liked school and most of the subjects. I especially liked that math and science subjects were objective. Your answer to a problem is either right or wrong. But I really thought I wanted to be a lawyer. 

How did you decide to attend Grambling State University in Louisiana? 

I wanted to go away somewhere different than Colorado. I applied to a few schools randomly but I got a scholarship to Grambling and so I went there. I loved being in the South. It was so green while Colorado is so dry. Also, Colorado’s population is about 4 percent Black. My experience with Black people was mainly limited to church and family. Grambling is an Historically Black College and University and probably 96 percent Black. It was nice to meet Black people from all over the country and from all different socio-economic backgrounds. I played the flute and piccolo and I joined Grambling’s famous marching band. The band is really tight knit and that made it easy for me to build community there. I really value that. 

I also valued how the professors interacted with students. I was a criminal justice major, but I took a high-level calculus class because math was important to me. The professor eventually called me into his office and said, “You should change your major to math.” I thought about it and I realized that he was right, so I did. 

What prompted your interest in modeling the coastal effects of hurricanes? 

I was a sophomore in 2005 when Hurricanes Katrina and Rita hit the Gulf Coast. The university is in northern Louisiana and we didn’t deal with the storm surges, but I remember the rain. And a lot of students were from places along the Gulf Coast. That allowed me to see the personal impacts of hurricanes. One of the band members was from New Orleans and his sister was killed in a shelter. I realized that it was people who looked like me on the news, sitting on roofs, and seemingly not being taken care of. Seeing that societal impact, particularly for my community, sparked my interest in trying to do something about it. 

The following summer I got an internship at the National Center for Atmospheric Research. I worked on a project to try to understand the relationship between the intensity of storms and atmospheric water vapor. I realized how much I loved research and doing something beyond analytical math that had a practical application. 

You went on to become the first African-American PhD student at what is now known as the Oden Institute for Computational Engineering and Sciences at the University of Texas. What was that experience like? 

The transition was very difficult. Initially, I felt isolated within the institute as the only Black person. You may not even be conscious of it, but if there is no one that looks like you who is studying or teaching in a program, it’s like a silent message. I had to get up to speed in computational math, there was this big learning curve, and I also was dealing with culture shock. I couldn’t relate to people on a personal level and I was intimidated, thinking everyone else was so far ahead of me. It took me a while to get myself together and adjust. 

UT Austin is mid-way between Dallas and Houston and near Louisiana, so it was relatively easy for me to connect with people that I knew, which was healthy for me. And once I got into my research things got much better. I loved working with mathematical models and computer coding. I had a really great advisor. The day I defended my dissertation went as smoothly as it could have gone. The timing, the way I answered questions, the way the sun looked when I walked out of the building. That was a perfect day. 

The net was positive. My initial struggles in graduate school make me a better mentor now. 

How do you sum up your research? 

I use a computer to solve math problems surrounding the way that fluid flows during storms. I work with a model that doesn’t have to depend on historical data from storms in coastal communities. I can change a variable in the model and determine how that may affect a storm’s impact. One of the scenarios that I look at a lot is variables due to climate change. 

I don’t study the atmosphere. I study the response of the ocean to the atmosphere. Many people get focused on the category of a hurricane, which tells you the wind strength. But there is also the hazard from water, via storm surge and inland flooding. The water hazards also pose a great threat to the built environment. And human deaths from hurricanes are usually related to water. 

What improvements would you like to see in national hurricane research?  

The hazards are multi-dimensional so we should not study the problems underlying them in isolation. Katrina was catastrophic not just became of the storm but because New Orleans is below sea level, it’s densely populated, and there was a failure of infrastructure. And there are bigger questions than those surrounding physical infrastructure. How do we develop the social infrastructure needed so that low-income people can evacuate in an emergency? How do we foster resilience? 

We need more science in politics if we want to protect coastlines. We need truly inter-disciplinary teams tackling the problems funded over 20-year timescales, so we don’t just do things halfway. As a nation, we’re so reactionary. But only one dollar in prevention equals six dollars spent on a reaction. 

Why did you decide to come to Emory? 

The faculty here really care about teaching and so do I. The students are well-supported, especially in the Department of Mathematics. And I feel valued as a truly inter-disciplinary researcher. I don’t belong in a box. Emory offers a lot of opportunity to grow as my interests evolve. I can collaborate with faculty from the Department of Environmental Sciences, the Department of Computer Science, the Rollins School of Public Health and elsewhere across campus. 

What do you hope will be your academic legacy? 

I want to make an impact scientifically. I want to write good papers and to advance knowledge. And, at the end of the day, I hope that people will say, “She was kind. She treated people well while she achieved those things.”

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New lead screening index zooms in on highest-risk areas in Georgia

Click here to see an interactive version of the map of priority screening index scores for low-level lead exposure in Georgia. Emory researchers, in partnership with health officials, are offering free soil testing of lead levels for Georgia residents through November 15. Click here for details.

By Carol Clark

While many people think of lead poisoning as a problem of the past, chronic exposure still occurs in some communities that may be missed in limited screening programs for children’s blood lead levels. Now researchers at Emory University have developed a more precise screening index, illustrated with a map, which provides a fine-grain view of areas where children are most at risk for low-level lead exposure in the city of Atlanta and throughout the state of Georgia. 

Scientific Reports published their new method, including analyses that tested and showed its efficacy, using historical data. 

The new screening index is based on established risk factors for lead exposure, including poverty and housing built before 1950. The index pinpointed 18 highest-priority census tracts in metro Atlanta, encompassing 2,715 children under the age of six — or 1.7 percent of all children that age in greater Atlanta. 

These highest-priority areas include the historically black neighborhoods of English Avenue and Vine City, where Emory researchers had previously identified elevated levels of lead in the soil of some yards and vacant lots. 

“As we move forward into an age when acute lead poisoning is rare, we need better tools to monitor for chronic, long-term exposure to lead,” says Emory graduate Samantha Distler, first author of the paper. “We developed an interactive map that can be used by physicians and other health officials, and even by individuals who want to check their own children’s risk levels. You can easily zoom in to find an exact location, so there’s less guess work involved in assessing what is a high-risk area.” 

The method could be applied to any area in the United States, she adds. 

Distler led the work as an Emory undergraduate majoring in quantitative sciences on the neuroscience and behavioral biology track. She is now a graduate student of epidemiology at the University of Michigan School of Public Health. 

“Lead is a toxicant that is particularly dangerous to children and their developing brains,” Distler says. “Even low blood lead levels are associated with neurological deficits in children.” 

“One of the biggest problems concerning lead is that many people don’t know if their children are being exposed,” says Eri Saikawa, senior author of the study and associate professor in Emory’s Department of Environmental Sciences and Rollins School of Public Health. “Detecting lead exposure as early as possible is very important so preventative measures can be taken. The easiest way to do that is to screen the blood.” 

The Saikawa lab is offering free soil testing of lead levels for Georgia residents through November 15, in partnership with the Georgia Department of Health, the Agency for Toxic Substances and Disease Registry and Georgia Adopt-A-Stream. Click here for details of how to collect a sample and where to drop it off. 

In 2018, the Saikawa lab collaborated with members of Atlanta’s Historic Westside Gardens to test urban soil on Atlanta’s Westside for contaminants. That project uncovered high levels of heavy metal and metalloids in some yards, and even some industrial waste known as slag. The project led to an investigation by the U.S. Environmental Protection Agency, which in 2019 began decontaminating properties in the area by removing and replacing soil. 

In addition to neurological deficits, lead exposure is associated with immunological and endocrine effects and cardiovascular disease. Decades ago, federal regulations reduced lead in paint and gasoline and other common exposure sources. The resulting drop in children’s blood lead levels in the United States is considered one of the greatest public health achievements in the country’s history. 

Many people remain unaware, however, that lead persists in the environment. “It can linger for a really long time in everything from soil to water,” Distler says. “That puts some people at risk for chronic exposures to low levels over a long time.” 

The Centers for Disease Control and Prevention (CDC) estimates that at least four million households in the United States have children living in them who are being exposed to high levels of lead. And about half a million of those children aged one to five years have blood lead levels above five micrograms per deciliter, the level at which the CDC recommends initiating public health action. 

Despite this alarming statistic, many children in higher-risk areas are not screened for blood lead levels. In Georgia, data from the period 2011 to 2018 show that the proportion in various ZIP code tabulation areas who have been tested range from 1 percent to 67 percent, with a median of 13 percent. 

The Emory researchers realized that one problem may be that health officials focus screening efforts on a county-wide basis, rather than zeroing in on the highest-risk neighborhoods within those counties. 

In 2009, a team led by researchers at the CDC developed and published a priority screen index for Atlanta neighborhoods based on housing age and percentage of residents enrolled in Georgia’s Special Supplemental Nutrition Program for Women, Infants and Children (WIC), a proxy for poverty. 

For the current paper, the Emory researchers built on the efforts of the 2009 paper, drilling down from neighborhoods to more precise U.S. Census Bureau tracts. Data from the American Community Survey was used to assess the relative level of poverty and proportion of homes built before 1950. 

A priority screening index, ranging from two to eight, was applied to the census tracts. The areas of highest relative poverty and proportion of homes built before 1950 received the highest score. The researchers applied this index to census tracts across the state of Georgia and to the entire United States to identify tracts that consistently have the highest priority screening index values. 

“The visualizations of our priority screening index that we’ve created using interactive maps can empower physicians and health officials to better target children at high risk for lead exposure,” Distler says. “We hope our work will help lead to improved policies and actions to reach children who are most at risk for lead exposure and to improve their lives — not just in Georgia but throughout the United States.”

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