Wednesday, November 17, 2021

How grandmothers' brains react to the sight of their grandchildren

"We're highlighting the brain functions of grandmothers that may play an important role in our social lives and development," says Minwoo Lee, an Emory graduate student and co-author of the study. "It's an important aspect of the human experience that's been largely left out of the field of neuroscience."

By Carol Clark

Many people lucky enough to have grown up with doting grandmothers know that they can burnish a child’s development in unique and valuable ways. Now, for the first time, scientists have scanned grandmothers’ brains while they’re viewing photos of their young grandchildren — providing a neural snapshot of this special, inter-generational bond. 

Proceedings of the Royal Society B published the first study to examine grandmaternal brain function, conducted by researchers at Emory University. 

“What really jumps out in the data is the activation in areas of the brain associated with emotional empathy,” says James Rilling, lead author and professor in Emory's Department of Anthropology and Department of Psychiatry and Behavioral Sciences. “That suggests that grandmothers are geared toward feeling what their grandchildren are feeling when they interact with them. If their grandchild is smiling, they’re feeling the child’s joy. And if their grandchild is crying, they’re feeling the child’s pain and distress.” 

In contrast, the study found that when grandmothers view images of their adult child, they show stronger activation in an area of the brain associated with cognitive empathy. That indicates they may be trying to cognitively understand what their adult child is thinking or feeling and why, but not as much from the emotional side. 

“Young children have likely evolved traits to be able to manipulate not just the maternal brain, but the grand maternal brain,” Rilling says. “An adult child doesn’t have the same cute ‘factor,’ so they may not illicit the same emotional response.” 

Co-authors of the study are Minwoo Lee, a PhD candidate in Emory’s Department of Anthropology, and Amber Gonzalez, a former Emory research specialist. 

"What really jumps out in the data is the activation in areas of the brain associated with emotional empathy," Rilling says.

“I can relate to this research personally because I spent a lot of time interacting with both of my grandmothers,” Lee says. “I still remember warmly the moments I had with them. They were always so welcoming and happy to see me. As a child, I didn’t really understand why.” 

It’s relatively rare, Lee adds, for scientists to study the older human brain outside of the problems of dementia or other aging disorders. 

“Here, we’re highlighting the brain functions of grandmothers that may play an important role in our social lives and development,” Lee says. “It’s an important aspect of the human experience that has been largely left out of the field of neuroscience.” 

Rilling’s lab focuses on the neural basis of human social cognition and behavior. Motherhood has been extensively studied by other neuroscientists. Rilling is a leader in researching the lesser-explored neuroscience of fatherhood

Grandmothers interacting with grandchildren offered new neural territory. 

“Evidence is emerging in neuroscience for a global, parental caregiving system in the brain,” Rilling says. “We wanted to see how grandmothers might fit into that pattern.” 

Humans are cooperative breeders, meaning that mothers get help caring for their offspring, although the sources of that help vary both across and within societies. 

“We often assume that fathers are the most important caregivers next to mothers, but that’s not always true,” Rilling says. “In some cases, grandmothers are the primary helper.” 

In fact, the “grandmother hypothesis” posits that the reason human females tend to live long past their reproductive years is because they provide evolutionary benefits to their offspring and grandchildren. Evidence supporting this hypothesis includes a study of the traditional Hadza people of Tanzania, where foraging by grandmothers improves the nutritional status of their grandchildren. Another study of traditional communities showed that the presence of grandmothers decreases their daughters’ interbirth intervals and increases the number of grandchildren. 

And in more modern societies, evidence is accumulating that positively engaged grandmothers are associated with children having better outcomes on a range of measures, including academic, social, behavior and physical health. 

"If their grandchild is smiling, they're feeling the child's joy," Rilling says. "And if their grandchild is crying, they're feeling the child's pain and distress."

For the current study, the researchers wanted to understand the brains of healthy grandmothers and how that may relate to the benefits they provide to their families. 

The 50 participants in the study completed questionnaires about their experiences as grandmothers, providing details such as how much time they spend with their grandchildren, the activities they do together and how much affection they feel for them. They also underwent functional magnetic resonance imaging (fMRI) to measure their brain function as they viewed pictures of their grandchild, an unknown child, the same-sex parent of the grandchild, and an unknown adult. 

The results showed that, while viewing pictures of their grandchildren, most participants showed more activity in brain areas involved with emotional empathy and movement, compared to when they were viewing the other images. 

Grandmothers who more strongly activated areas involved with cognitive empathy when viewing pictures of their grandchild reported in the questionnaire that they desired greater involvement in caring for the grandchild. 

Finally, compared with results from earlier study by the Rilling lab of fathers viewing photos of their children, grandmothers more strongly activated regions involved with emotional empathy and motivation, on average, when viewing images of their grandchildren. 

“Our results add to the evidence that there does seem to be a global parenting caregiving system in the brain, and that grandmothers’ responses to their grandchildren maps onto it,” Rilling says. 

One limitation to the study, the researchers note, is that the participants skewed towards mentally and physically healthy women who are high-functioning grandmothers. 

The study opens the door to many more questions to be explored. “It would be interesting to also look at the neuroscience of grandfathers and how the brain functions of grandparents may differ across cultures,” Lee says. 

An especially gratifying aspect of the project for Rilling was personally interviewing all the participants himself. “It was fun,” he says. “I wanted to get a sense of the rewards and challenges of being a grandmother.” 

The main challenge many of them reported was trying not to interfere when they disagreed with the parents over how their grandchildren should be raised and what values should be instilled in them. 

“Many of them also said how nice it is to not be under as much time and financial pressure as they were when raising their children,” Rilling says. “They get to enjoy the experience of being a grandmother much more than they did being parents.” 

This work was supported in part by the Silvia O. Conte Center for Oxytocin and Social Cognition.


Five surprising facts about fathers

Brain scans link oxytocin to paternal nurturing

Dads show gender biases, in both brain responses and behaviors, toward toddlers

Tuesday, November 9, 2021

Biological studies often misinterpret sex-based data, analysis finds

"At this moment in history, the stakes are high," says Emory neuroscientist Donna Maney, senior author of the analysis. "Misreported findings may affect health care decisions in dangerous ways."

By Carol Clark

An analysis of published studies from a range of biological specialties shows that, when data are reported by sex, critical statistical analyses are often missing and the findings are likely to be reported in misleading ways. 

The journal eLife published the analysis, done by neuroscientists at Emory University, encompassing studies from nine different biological disciplines that involved either human or animal subjects. 

“We found that when researchers report that males and females respond differently to a manipulation such as a drug treatment, 70 percent of the time the researchers have not actually compared those responses statistically at all,” says senior author Donna Maney, a professor of neuroscience in Emory’s Department of Psychology. “In other words, an alarming percentage of claims of sex differences are not backed by sufficient evidence.” 

In the articles missing the proper evidence, she adds, sex-specific effects were claimed in nearly 90 percent of the cases. In contrast, authors that tested statistically for sex-specific effects reported them only 63 percent of the time. 

‘’Our results suggest that researchers are predisposed to finding sex differences and that sex-specific effects are likely over-reported in the literature,” Maney says. 

This particular problem is common and pertains to Maney’s own previous work, she adds. “Once I realized how prevalent it is, I went back and checked my own published articles and there it was,” she says. “I myself have claimed a sex difference without comparing males and females statistically.”

Maney stresses that the problem should not be discounted just because it is common. It is becoming increasingly serious, she says, because of mounting pressure from funding agencies and journals to study both sexes, and interest from the medical community to develop sex-specific treatments. 

Maney is a behavioral neuroendocrinologist interested in how research on sex differences shapes public opinion and policy. Rigorous standards are needed, she says, to ensure that people of all genders have access to care that is appropriate for them. 

Yesenia Garcia-Sifuentes, an Emory PhD candidate in the Graduate Program in Neuroscience, is co-author of the eLife analysis. 

Better training and oversight are needed to ensure scientific rigor in research on sex differences, the authors write: “We call upon funding agencies, journal editors and our colleagues to raise the bar when it comes to testing for and reporting sex differences.” 

More studies including sex-based variables 

Historically, biomedical research has often included just one sex, usually biased toward males. In 1993, Congress wrote a policy into law to ensure that women are included in clinical studies funded by the National Institutes of Health whenever feasible, and that the studies be carried out so that it is possible to analyze whether the variables being studied affect women differently than other participants. 

In 2016, the NIH announced a policy that also requires the consideration of sex as a biological variable when feasible in basic biological studies that it funds, whether that research involves animals or humans. 

“If you’re trying to model anything relevant to a general population, you should include both sexes,” Maney explains. “There are a lot of ways that animals can vary, and sex is one of them. Leaving out half of the population makes a study less rigorous.” 

As more studies consider sex-based differences, Maney adds, it is important ensure that the methods underlying their analyses are sound. 

For the eLife analysis, Garcia-Sifuentes and Maney looked at 147 studies published in 2019 to investigate what is typically used as evidence of sex differences. The studies ranged across nine different biological disciplines and included everything from field studies on giraffes to immune responses in humans. 

The studies that were analyzed all included both males and females and separated the data by sex. Garcia-Sifuentes and Maney found that the sexes were compared, either statistically or by assertion, in 80 percent of the articles. And, within those articles, sex differences were reported in 70 percent of them and treated as a major finding in about half of those. 

Some of the studies that reported a sex difference, however, committed a statistical error. For example, if researchers found a statistically significant effect of a treatment on one sex but not the other, they typically concluded a sex difference even if the effect of the treatment was not compared statistically between males and females. 

The problem with that approach is that the statistical tests conducted on each sex can’t give “yes” or “no” answers about whether the treatment had an effect. 

“Comparing the outcome of two independent tests is like comparing a ‘maybe so’ with an ‘I don’t know’ or ‘too soon to tell,’” Maney explains. “You’re just guessing. To show actual evidence that the response to treatment differed between females and males, you need to show statistically that the effect of treatment depended on sex. That is, to claim a ‘sex-specific’ effect, you must demonstrate that the effect in one sex was statistically different from the effect in the other.” 

On the flip side, the eLife analysis also encountered strategies that could mask sex differences, such as pooling data from males and females without testing for a difference. Maney recommends reporting the size of the difference — that is, the extent to which the sexes don’t overlap — before pooling data. She provides a free online tool that lets researchers visualize their data to assess the size of the difference. 

“At this moment in history, the stakes are high,” Maney says. “Misreported findings may affect health care decisions in dangerous ways. Particularly in cases where sex-based differences may be used to determine what treatment someone gets for a particular condition, we need to proceed cautiously. We need to hold ourselves to a very high standard when it comes to scientific rigor.”


Sex-based data in the spotlight

A beginner's guide to sex differences in the brain

Thursday, November 4, 2021

Into the heart of brightness: An ethnobotanist's memoir celebrates a life in science

"We have barely scratched the surface of the medicinal value of plants," says Emory ethnobotanist Cassandra Quave, shown in the field in South Georgia.

Cassandra Quave's story is like a tropical forest: Varied, colorful, bursting with life and and laced with hidden pathways that must be constantly cleared to move along them. Her new memoir guides readers through a world of plants and the people entwined with them. The story is sometimes dark but mostly uplifting, lit up by her personal revelations and scientific discoveries.

"The Plant Hunter: A Scientist's Quest for Nature's Next Medicines" was recently published by Viking. 

"I was inspired to write the book because people have found my work interesting," says Quave, associate professor in Emory's Center for the Study of Human Health and the School of Medicine. "It's a chance to tell the larger story of my life, bringing together all of the different parts of it."

Read more here.


New molecule found in chestnut leaves disarms dangerous staph bacteria

Wednesday, November 3, 2021

Youth views on climate crisis take world stage

Emory students and alumni are raising diverse voices on equity during the United Nations Conference of the Parties on Climate Change (COP26) now underway in Glasgow. This year, Emory is not sending an in-person student delegation, due to the pandemic and related concerns, says Eri Saikawa, associate professor of environmental sciences, who normally leads students at COP. Instead, the 17 undergraduate and six graduate students in Saikawa's "Climate and Society" class are contributing virtually by hosting virtual seminars for COP's Zero Emissions Solutions Conference. They are also producing a series of Emory Climate Talks seminars and AmpliFIRE podcasts, also aimed at bringing in diverse viewpoints to discuss key issues at COP.

Read the full story here.


Peachtree to Paris: Emory delegation headed to U.N. climate talks

Tuesday, November 2, 2021

A new way to measure tech complexity

As humans evolved our brains became bigger and our technology became more complex. While brains can be compared by size and other concrete measures of form and physiology, quantifying technological complexity has proven more challenging. 

“Although we know that some human technologies have grown more complex and sophisticated with time, we actually don’t know exactly what we mean when we say that because we haven’t had a good way to measure that complexity,” says Dietrich Stout, associate professor of anthropology at Emory University. “Is a straight razor more, or less complex, than a baseball bat? Are Polynesian fishing nets more, or less, complicated than lassoes used by reindeer herders in Lapland?” 

Now, Stout and colleagues have developed the first computational method to measure fluid human actions to try to answer such questions. Scientific Reports published their method, based on the making and use of different types of Stone Age tools.