Bats Evolved More Than One Way to Drink Nectar

ScienceDaily (Aug. 17, 2012) — A team of evolutionary biologists compared the anatomy and genes of bats to help solve a persistent question in evolution: Why do analyses of different features of an organism result in conflicting patterns of evolutionary relationships? Their findings, “Understanding phylogenetic incongruence: lessons from phyllostomid bats,” appear in the August 14 edition of Biological Reviews.

Two nectar-feeding bats in the Neotropical family Phyllostomidae; the glossophagine Pallas’s long-tongued bat, Glossophaga soricina, (left) and the lonchophylline orange nectar bat, Lonchophylla robusta, (right). In a new study Dávalos, Cirranello, et al., show that many anatomical features implying a common origin of nectar feeding for glossophagines and lonchophyllines — such as a long, extensible tongue — are related to their shared diet. Their evolutionary patterns are consistent with natural selection. (Credit: Felineora (left), Marco Tschapka (right).)


 

To answer this question, Liliana Dávalos, PhD, Assistant Professor in the Department of Ecology and Evolution, and member of the Consortium for Inter-Disciplinary Environmental Research (CIDER) at Stony Brook University, and Andrea Cirranello of the Division of Vertebrate Zoology at the American Museum of Natural History (AMNH), together with colleagues at the AMNH and the New York College of Osteopathic Medicine, examined the skin, skeleton, muscle, tongue, internal organs and a few genes of a family of New World bats, applying statistical models to uncover the genetic and anatomical features that produced the conflicts between evolutionary patterns. This work was funded in part by the National Science Foundation.

Specifically, the team examined why genes suggested that nectar feeding had evolved twice in Leaf-Nosed bats, while the anatomical features strongly pointed to a single origin of nectar feeding in this group. Most bats feed on insects, but New World Leaf-Nosed bats are exceptionally diverse in that they feed on nectar, fruit, frogs, lizards and even blood.

One hypothesis that the team tested is that traits linked to how bats feed have been shaped by natural selection for a nectar-based diet, resulting in the conflicting pattern. As Dávalos and Cirranello explain, connecting the conflicting pattern to the diet requires showing that the evolutionary pattern resulting from anatomical traits is wrong, and that the traits producing the conflict with the genetic data are linked to a shared dietary specialization.

“If a diet specializing in nectar helped shape the anatomy of the two groups of bats, then the traits that support the groups coming together should be related to feeding, and taking those traits out should break up the spurious group of nectar-feeding bats,” the researchers said. They found support for these predictions by analyzing evolutionary trees from two genomic data sets, alongside trees based on more than 200 anatomical traits; and applying a battery of statistical approaches to identify where in the evolutionary tree the conflicts arose and what genetic regions and traits supported the differences.

The team traced the conflict in evolutionary patterns among nectar-feeding bats to traits linked to feeding, such as the shape and number of teeth, gaining a “paintbrush” type tongue tip, and rearranging the tongue muscles to accommodate longer, extensible tongues. All of these traits are thought to be associated with specialized nectar feeding. The grouping of all nectar-feeding bats broke down into smaller groups when those traits were taken out of the analyses. Overall, the team found that anatomical traits and the studied genes tended to agree on many parts of the evolutionary tree, but that the anatomical traits associated with nectar feeding brought nectar-feeding bats together.

Natural selection has shaped the anatomy of organisms, but when specializations evolved long ago, it can be difficult for evolutionary biologists to demonstrate that traits bear its signature. By ruling out other biological processes that produce conflict among evolutionary trees, and tracing the conflict to specific traits that are known to enable drinking nectar, the team was able to narrow the options and discover patterns consistent with the signature of adaptation to diet. “We found that anatomical traits associated with nectar feeding have evolved and been lost several times, so they tend to bring bats from different branches of the evolutionary tree together, in direct conflict with genetic trees,” Dávalos and Cirranello said.


Story Source:

The above story is reprinted from materials provided by Stony Brook University.


Journal Reference:

  1. Liliana M. Dávalos, Andrea L. Cirranello, Jonathan H. Geisler, Nancy B. Simmons. Understanding phylogenetic incongruence: lessons from phyllostomid bats. Biological Reviews, 2012; DOI: 10.1111/j.1469-185X.2012.00240.x

Citation:

Stony Brook University (2012, August 17). Bats evolved more than one way to drink nectar. ScienceDaily. Retrieved August 23, 2012, from http://www.sciencedaily.com­ /releases/2012/08/120817151501.htm
Advertisements

Iconic Darwin Finch Genome Sequenced

ScienceDaily (Aug. 17, 2012) — Scientists have sequenced the genome of one of the iconic Galapagos finches first described by Charles Darwin. The genome of the medium ground finch (Geospiza fortis) is among the first of a planned 100 genomes of vertebrate species to be sequenced and released by an international collaboration between the Genome 10K project and BGI.

Scientists have sequenced the genome of one of the iconic Galapagos finches first described by Charles Darwin, the medium ground finch (Geospiza fortis). (Credit: © jptenor / Fotol)

 

This finch genome, the first of the BGI-Genome 10K collaboration to be made available through the UCSC Genome Browser, represents both a scientific and a symbolic advancement, according to Duke University associate professor Erich Jarvis, who studies the neurobiology of vocal learning in songbirds.

“The scientific advancement,” Jarvis said, “is that it will allow us to investigate the genomes of a group of closely related species with a significant amount of diversity on an island population, allowing us to potentially better understand the genetics of trait evolution.”

Jarvis added, “It is symbolic because it was the diversity of phenotypes in these finches that contributed to Darwin’s theory of evolution.”

Endemic to the subtropical or tropical dry forests and shrublands of the Galapagos Islands, this species evolves rapidly in response to environmental changes.

The BGI’s associate director of research, Goujie Zhang, said, “These finches are of great historical significance, but when Darwin first studied these birds, he was unlikely to have envisioned how this species would become a perfect model to study evolution in action.”

Zhang said, “Having the reference genome of this species has opened the door for carrying out studies that can look at real-time evolutionary changes on a genomic level of all of these enigmatic species.”

Jarvis said this new genome will help us understand the evolution of vocal learning, “The availability of the Geospiza fortis will allow us to validate findings so far only found in the zebra finch genome.”

Jarvis said these include genes with positively selected mutations involved with the vocal learning trait in finches and also with behavior necessary for spoken language in humans.

Jarvis added that the medium ground finch has several song types, whereas the zebra finch “is a more stereotyped vocal learning species.” This difference is expected to be under genetic control.

Adding richness to the possibility of understanding the genomic components of vocal learning, researchers have been recording Geospiza songs over the last 40 years.

Jarvis said these recordings reveal dialectic patterns that can now be linked to the genome by sequencing the genomes of additional individuals from living and past populations. “Like human spoken language, Geospiza song dialects are stable over many generations, but can change with emigration.”

“Having the well assembled draft reference genome of one individual will now allow scientists to determine if this cultural evolution is partly affected by genetics or is all pure cultural transmission,” Jarvis added.

In addition to being useful for investigating speciation, the genomic data can help in conservation efforts, Zhang said. “They also serve as the base for population studies that will aid in the conservation of these renowned finches. BGI is looking forward to working with any collaborators interested in joining us to carry out this work.”

Zhang said the medium ground finch genome, which is nearly one-third the size of the human genome, was sequenced from an individual female, producing a high-quality draft using 115X coverage data from the Illumina HiSeq sequencing system, which is considered a “next-generation” technology. With the aid of transcriptome data, BGI was able to annotate 16,286 protein-coding genes in this genome.

Professor Jun Wang, Executive Director of BGI, indicated the groups acted to spur the most rapid access and use of these data and to enable and encourage pre-publication use.

For that reason, in addition to releasing the medium ground finch genome on the UCSC Genome Browser, BGI has openly released the genome in their GigaScience journal’s database, GigaDB, which makes data available in a citable format and hosts it under a CC0 license that provides the least restrictions possible for data use.

According to Genome 10K co-founder Stephen O’Brien, “The genome sequence empowerment of Darwin’s finches will initiate the solving of evolutionary riddles that have puzzled biologists for a century.” O’Brien is now chief scientific officer and director of the Dobzhansky Center for Genome Bioinformatics at St. Petersburg State University, Russia.

Oliver Ryder, director of genomics at the San Diego Zoo, placed the new genome in a larger context: “The availability of this high quality genome assembly produced by BGI will facilitate the stewardship of earth’s biodiversity — a cherished goal of Genome10K.”

 


Story Source:

The above story is reprinted from materials provided byBGI Shenzhen, via EurekAlert!, a service of AAAS.


Journal Reference:

  1. Zhang, G; Parker, P; Li, B; Li, H; Wang, J. The genome of Darwin’s Finch (Geospiza fortis)GigaScience, 2012 DOI: 10.5524/100040
Citation:

BGI Shenzhen (2012, August 17). Iconic Darwin finch genome sequenced.ScienceDaily. Retrieved August 23, 2012, from http://www.sciencedaily.com/releases/2012/08/120817093049.htm

Secrets of ‘SuperAger’ Brains: Elderly Super-Agers Have Brains That Look and Act Decades Younger Than Their Age

ScienceDaily (Aug. 16, 2012) — Researchers have long chronicled what goes wrong in the brains of older people with dementia. But Northwestern Medicine researcher Emily Rogalski wondered what goes right in the brains of the elderly who still have terrific memories. And, do those people — call them cognitive SuperAgers — even exist?

Dosuper-agers exist? A new study has for the first time identified an elite group of elderly people age 80 and older whose memories are as sharp as people 20 to 30 years younger than them. (Credit: © Meddy Popcorn / Fotolia)

 

Rogalski’s new study has for the first time identified an elite group of elderly people age 80 and older whose memories are as sharp as people 20 to 30 years younger than them. And on 3-D MRI scans, the SuperAger participants’ brains appear as young — and one brain region was even bigger — than the brains of the middle-aged participants.

She was astounded by the vitality of the SuperAgers’ cortex — the outer layer of the brain important for memory, attention and other thinking abilities. Theirs was much thicker than the cortex of the normal group of elderly 80 and older (whose showed significant thinning) and closely resembled the cortex size of participants ages 50 to 65, considered the middle-aged group of the study.

“These findings are remarkable given the fact that grey matter or brain cell loss is a common part of normal aging,” said Rogalski, the principal investigator of the study and an assistant research professor at the Cognitive Neurology and Alzheimer’s Disease Center at Northwestern University Feinberg School of Medicine.

Rogalski is senior author of the paper, which is published in the Journal of the International Neuropsychological Society.

By identifying older people who seem to be uniquely protected from the deterioration of memory and atrophy of brain cells that accompanies aging, Rogalski hopes to unlock the secrets of their youthful brains. Those discoveries may be applied to protect others from memory loss or even Alzheimer’s disease.

“By looking at a really healthy older brain, we can start to deduce how SuperAgers are able to maintain their good memory,” Rogalski said. “Many scientists study what’s wrong with the brain, but maybe we can ultimately help Alzheimer’s patients by figuring out what goes right in the brain of SuperAgers. What we learn from these healthy brains may inform our strategies for improving quality of life for the elderly and for combatting Alzheimer’s disease.”

By measuring the thickness of the cortex — the outer layer of the brain where neurons (brain cells) reside — Rogalski has a sense of how many brain cells are left.

“We can’t actually count them, but the thickness of the outer cortex of the brain provides an indirect measure of the health of the brain,” she said. “A thicker cortex, suggests a greater number of neurons.”

In another region deep in the brain, the anterior cingulate of SuperAger participants’ was actually thicker than in the 50 to 65 year olds.

“This is pretty incredible,” Rogalski said. “This region is important for attention. Attention supports memory. Perhaps the SuperAgers have really keen attention and that supports their exceptional memories.”

Only 10 percent of the people who “thought they had outstanding memories” met the criteria for the study. To be defined as a SuperAger, the participants needed to score at or above the norm of the 50 to 65 year olds on memory screenings.

“These are a special group of people,” Rogalski said. They aren’t growing on trees.”

For the study, Rogalski viewed the MRI scans of 12 Chicago-area Superager participants’ brains and screened their memory and other cognitive abilities. The study included 10 normally aging elderly participants who were an average age of 83.1 and 14 middle-aged participants who were an average age of 57.9. There were not significant differences in education among the groups.

Most of the SuperAger participants plan to donate their brains to the study. “By studying their brains we can link the attributes of the living person to the underlying cellular features,” Rogalski said.

 


Story Source:

The above story is reprinted from materials provided byNorthwestern University, via EurekAlert!, a service of AAAS. 


Journal Reference:

  1. Theresa M. Harrison, Sandra Weintraub, M.-Marsel Mesulam and Emily Rogalski. Superior Memory and Higher Cortical Volumes in Unusually Successful Cognitive AgingJournal of the International Neuropsychological Society, 2012 DOI:10.1017/S1355617712000847
Citation:

Northwestern University (2012, August 16). Secrets of ‘SuperAger’ brains: Elderly super-agers have brains that look and act decades younger than their age. ScienceDaily. Retrieved August 19, 2012, from http://www.sciencedaily.com/releases/2012/08/120816201620.htm

Organisms Cope With Environmental Uncertainty by Guessing the Future

ScienceDaily (Aug. 16, 2012) — In uncertain environments, organisms not only react to signals, but also use molecular processes to make guesses about the future, according to a study by Markus Arnoldini et al. from ETH Zurich and Eawag, the Swiss Federal Institute of Aquatic Science and Technology. The authors report in PLoS Computational Biology that if environmental signals are unreliable, organisms are expected to evolve the ability to take random decisions about adapting to cope with adverse situations.

Most organisms live in ever-changing environments, and are at times exposed to adverse conditions that are not preceded by any signal. Examples for such conditions include exposure to chemicals or UV light, sudden weather changes or infections by pathogens. Organisms can adapt to withstand the harmful effects of these stresses. Previous experimental work with microorganisms has reported variability in stress responses between genetically identical individuals. The results of the present study suggest that this variation emerges because individual organisms take random decisions, and such variation is beneficial because it helps organisms to reduce the metabolic costs of protection without compromising the overall benefits.

The theoretical results of this study can help to understand why genetically identical organisms often express different traits, an observation that is not explained by the conventional notion of nature and nurture. Future experiments will reveal whether the predictions made by the mathematical model are met in natural systems.

 


Story Source:

The above story is reprinted from materials provided byPublic Library of Science.


Journal Reference:

  1. Markus Arnoldini, Rafal Mostowy, Sebastian Bonhoeffer, Martin Ackermann. Evolution of Stress Response in the Face of Unreliable Environmental SignalsPLoS Computational Biology, 2012; 8 (8): e1002627 DOI:10.1371/journal.pcbi.1002627
Citation:

Public Library of Science (2012, August 16). Organisms cope with environmental uncertainty by guessing the future.ScienceDaily. Retrieved August 19, 2012, from http://www.sciencedaily.com/releases/2012/08/120816201616.htm

Interest in Arts Predicts Social Responsibility

ScienceDaily (Aug. 16, 2012) — If you sing, dance, draw, or act — and especially if you watch others do so — you probably have an altruistic streak, according to a study by researchers at the University of Illinois at Chicago.

If you sing, dance, draw, or act — and especially if you watch others do so — you probably have an altruistic streak. (Credit: © Sandra Cunningham / Fotolia)

 

People with an active interest in the arts contribute more to society than those with little or no such interest, the researchers found. They analyzed arts exposure, defined as attendance at museums and dance, music, opera and theater events; and arts expression, defined as making or performing art.

“Even after controlling for age, race and education, we found that participation in the arts, especially as audience, predicted civic engagement, tolerance and altruism,” said Kelly LeRoux, assistant professor of public administration at UIC and principal investigator on the study.

In contrast to earlier studies, Generation X respondents were found to be more civically engaged than older people.

LeRoux’s data came from the General Social Survey, conducted since 1972 by the National Data Program for the Sciences, known by its original initials, NORC. A national sample of 2,765 randomly selected adults participated.

“We correlated survey responses to arts-related questions to responses on altruistic actions — like donating blood, donating money, giving directions, or doing favors for a neighbor — that place the interests of others over the interests of self,” LeRoux said. “We looked at ‘norms of civility.’ Previous studies have established norms for volunteering and being active in organizations.”

The researchers measured participation in neighborhood associations, church and religious organizations, civic and fraternal organizations, sports groups, charitable organizations, political parties, professional associations and trade unions.

They measured social tolerance by two variables:

  • Gender-orientation tolerance, measured by whether respondents would agree to having gay persons speak in their community or teach in public schools, and whether they would oppose having homosexually themed books in the library.
  • Racial tolerance, measured by responses regarding various racial and ethnic groups, including African-Americans, Hispanics, and Asian Americans. Eighty percent of the study respondents were Caucasian, LeRoux said.

The researchers measured altruistic behavior by whether respondents said they had allowed a stranger to go ahead of them in line, carried a stranger’s belongings, donated blood, given directions to a stranger, lent someone an item of value, returned money to a cashier who had given too much change, or looked after a neighbor’s pets, plants or mail.

“If policymakers are concerned about a decline in community life, the arts shouldn’t be disregarded as a means to promote an active citizenry,” LeRoux said. “Our positive findings could strengthen the case for government support for the arts.”

The study was based on data from 2002, the most recent year in which the General Social Survey covered arts participation. LeRoux plans to repeat the study with results from the 2012 survey, which will include arts data.

 


Story Source:

The above story is reprinted from materials provided byUniversity of Illinois at Chicago. 


Citation:

University of Illinois at Chicago (2012, August 16). Interest in arts predicts social responsibility. ScienceDaily. Retrieved August 19, 2012, from http://www.sciencedaily.com/releases/2012/08/120816151809.htm

Evolutionary Increase in Size of the Human Brain Explained: Part of a Protein Linked to Rapid Change in Cognitive Ability

ScienceDaily (Aug. 16, 2012) — Researchers have found what they believe is the key to understanding why the human brain is larger and more complex than that of other animals.

(Credit: http://www.jokeroo.com/pictures/funny/brain-phone.html)

 

The human brain, with its unequaled cognitive capacity, evolved rapidly and dramatically.

“We wanted to know why,” says James Sikela, PhD, who headed the international research team that included researchers from the University of Colorado School of Medicine, Baylor College of Medicine and the National Institutes of Mental Health. “The size and cognitive capacity of the human brain sets us apart. But how did that happen?”

“This research indicates that what drove the evolutionary expansion of the human brain may well be a specific unit within a protein — called a protein domain — that is far more numerous in humans than other species.”

The protein domain at issue is DUF1220. Humans have more than 270 copies of DUF1220 encoded in the genome, far more than other species. The closer a species is to humans, the more copies of DUF1220 show up. Chimpanzees have the next highest number, 125. Gorillas have 99, marmosets 30 and mice just one. “The one over-riding theme that we saw repeatedly was that the more copies of DUF1220 in the genome, the bigger the brain. And this held true whether we looked at different species or within the human population.”

Sikela, a professor at the CU medical school, and his team also linked DUF1220 to brain disorders. They associated lower numbers of DUF1220 with microcephaly, when the brain is too small; larger numbers of the protein domain were associated with macrocephaly, when the brain is too large.

The findings were reported today in the online edition of TheAmerican Journal of Human Genetics. The researchers drew their conclusions by comparing genome sequences from humans and other animals as well as by looking at the DNA of individuals with microcephaly and macrocephaly and of people from a non-disease population.

“The take home message was that brain size may be to a large degree a matter of protein domain dosage,” Sikela says. “This discovery opens many new doors. It provides new tools to diagnose diseases related to brain size. And more broadly, it points to a new way to study the human brain and its dramatic increase in size and ability over what, in evolutionary terms, is a short amount of time.”

 


Story Source:

The above story is reprinted from materials provided byUniversity of Colorado Denver, via EurekAlert!, a service of AAAS.


Journal Reference:

  1. Laura J. Dumas, Majesta S. O’Bleness, Jonathan M. Davis, C. Michael Dickens, Nathan Anderson, J.G. Keeney, Jay Jackson, Megan Sikela, Armin Raznahan, Jay Giedd, Judith Rapoport, Sandesh S.C. Nagamani, Ayelet Erez, Nicola Brunetti-Pierri, Rachel Sugalski, James R. Lupski, Tasha Fingerlin, Sau Wai Cheung, James M. Sikela.DUF1220-Domain Copy Number Implicated in Human Brain-Size Pathology and EvolutionThe American Journal of Human Genetics, 2012; DOI:10.1016/j.ajhg.2012.07.016
Citation:

University of Colorado Denver (2012, August 16). Evolutionary increase in size of the human brain explained: Part of a protein linked to rapid change in cognitive ability. ScienceDaily. Retrieved August 19, 2012, from http://www.sciencedaily.com/releases/2012/08/120816141537.htm

Brain Scans Don’t Lie About Age

ScienceDaily (Aug. 16, 2012) — It isn’t uncommon for people to pass for ages much older or younger than their years, but researchers have now found that this feature doesn’t apply to our brains. The findings reported online on August 16 in Current Biology, a Cell Press publication, show that sophisticated brain scans can be used to accurately predict age, give or take a year.

The “developmental clock” shows increases and decreases in brain’s cortical surface, as well as the dynamic cascade of many other brain measures, all changing with increasing age (from age 3-20). (Credit: University of California San Diego of Medicine)

 

It’s a “carnival trick” that may have deeper implications for both brain science and medicine.

“We have uncovered a ‘developmental clock’ of sorts within the brain — a biological signature of maturation that captures age differences quite well, regardless of other kinds of differences that exist across individuals,” says Timothy Brown of the University of California, San Diego School of Medicine.

Together with UCSD’s Anders Dale and Terry Jernigan and researchers from nine other universities, Brown used structural magnetic resonance imaging (MRI) to scan the brains of 885 people ranging in age from 3 to 20. Those brain scans were used to identify 231 biomarkers of brain anatomy that, when combined, could assess an individual’s age with more than 92 percent accuracy. That’s beyond what’s been possible with any other biological measure, the researchers say.

While others had looked at some of the same brain biomarkers in the past one by one, the key was finding a way to combine them to capture the multidimensional nature of brain anatomy and characteristic patterns of developmental change with age. Brown says that they are excited to further explore the new approach and its potential for use in the clinic.

“The fact that we found a collection of brain measures that so accurately captures a person’s chronological age means that brain development, or at least certain anatomical aspects of it, is more tightly controlled than we knew previously,” Brown says. “The regularity in this maturity metric among typically developing children suggests that it might be sensitive to detecting abnormality as well.”

It’s not yet clear how these anatomical changes in the brain will relate to maturity in terms of human behavior, which we all know isn’t necessarily reflected by our chronological age.

“The anatomy and physiology of these dynamic, interacting neural systems, which we can probe in different ways with MRI scans, have to account for the changes we all observe in human psychological development,” Brown says. “We’re still figuring out exactly how.”

 

Story Source:

The above story is reprinted from materials provided byCell Press, via EurekAlert!, a service of AAAS.


Journal Reference:

  1. Timothy T. Brown, Joshua M. Kuperman, Yoonho Chung, Matthew Erhart, Connor McCabe, Donald J. Hagler, Vijay K. Venkatraman, Natacha Akshoomoff, David G. Amaral, Cinnamon S. Bloss, B.J. Casey, Linda Chang, Thomas M. Ernst, Jean A. Frazier, Jeffrey R. Gruen, Walter E. Kaufmann, Tal Kenet, David N. Kennedy, Sarah S. Murray, Elizabeth R. Sowell, Terry L. Jernigan, Anders M. Dale. Neuroanatomical Assessment of Biological MaturityCurrent Biology, 2012; DOI:10.1016/j.cub.2012.07.002
Citation:

Cell Press (2012, August 16). Brain scans don’t lie about age. ScienceDaily. Retrieved August 19, 2012, from http://www.sciencedaily.com/releases/2012/08/120816121954.htm

Why Are Elderly Duped? Area in Brain Where Doubt Arises Changes With Age

ScienceDaily (Aug. 16, 2012) — Everyone knows the adage: “If something sounds too good to be true, then it probably is.” Why, then, do some people fall for scams and why are older folks especially prone to being duped?

Patients with damage to the ventromedial prefrontal cortex were roughly twice as likely to believe a given ad, even when given disclaimer information pointing out it was misleading. And, they were more likely to buy the item, regardless of whether misleading information had been corrected. (Credit: Photo by Bill Adams)

 

An answer, it seems, is because a specific area of the brain has deteriorated or is damaged, according to researchers at the University of Iowa. By examining patients with various forms of brain damage, the researchers report they’ve pinpointed the precise location in the human brain, called the ventromedial prefrontal cortex, that controls belief and doubt, and which explains why some of us are more gullible than others.

“The current study provides the first direct evidence beyond anecdotal reports that damage to the vmPFC (ventromedial prefrontal cortex) increases credulity. Indeed, this specific deficit may explain why highly intelligent vmPFC patients can fall victim to seemingly obvious fraud schemes,” the researchers wrote in the paper published in a special issue of the journal Frontiers in Neuroscience.

A study conducted for the National Institute of Justice in 2009 concluded that nearly 12 percent of Americans 60 and older had been exploited financially by a family member or a stranger. And, a report last year by insurer MetLife Inc. estimated the annual loss by victims of elder financial abuse at $2.9 billion.

The authors point out their research can explain why the elderly are vulnerable.

“In our theory, the more effortful process of disbelief (to items initially believed) is mediated by the vmPFC, which, in old age, tends to disproportionately lose structural integrity and associated functionality,” they wrote. “Thus, we suggest that vulnerability to misleading information, outright deception and fraud in older adults is the specific result of a deficit in the doubt process that is mediated by the vmPFC.”

The ventromedial prefrontal cortex is an oval-shaped lobe about the size of a softball lodged in the front of the human head, right above the eyes. It’s part of a larger area known to scientists since the extraordinary case of Phineas Gage that controls a range of emotions and behaviors, from impulsivity to poor planning. But brain scientists have struggled to identify which regions of the prefrontal cortex govern specific emotions and behaviors, including the cognitive seesaw between belief and doubt.

The UI team drew from its Neurological Patient Registry, which was established in 1982 and has more than 500 active members with various forms of damage to one or more regions in the brain. From that pool, the researchers chose 18 patients with damage to the ventromedial prefrontal cortex and 21 patients with damage outside the prefrontal cortex. Those patients, along with people with no brain damage, were shown advertisements mimicking ones flagged as misleading by the Federal Trade Commission to test how much they believed or doubted the ads. The deception in the ads was subtle; for example, an ad for “Legacy Luggage” that trumpets the gear as “American Quality” turned on the consumer’s ability to distinguish whether the luggage was manufactured in the United States versus inspected in the country.

Each participant was asked to gauge how much he or she believed the deceptive ad and how likely he or she would buy the item if it were available. The researchers found that the patients with damage to the ventromedial prefrontal cortex were roughly twice as likely to believe a given ad, even when given disclaimer information pointing out it was misleading. And, they were more likely to buy the item, regardless of whether misleading information had been corrected.

“Behaviorally, they fail the test to the greatest extent,” says Natalie Denburg, assistant professor in neurology who devised the ad tests. “They believe the ads the most, and they demonstrate the highest purchase intention. Taken together, it makes them the most vulnerable to being deceived.” She added the sample size is small and further studies are warranted.

Apart from being damaged, the ventromedial prefrontal cortex begins to deteriorate as people reach age 60 and older, although the onset and the pace of deterioration varies, says Daniel Tranel, neurology and psychology professor at the UI and corresponding author on the paper. He thinks the finding will enable doctors, caregivers, and relatives to be more understanding of decision making by the elderly.

“And maybe protective,” Tranel adds. “Instead of saying, ‘How would you do something silly and transparently stupid,’ people may have a better appreciation of the fact that older people have lost the biological mechanism that allows them to see the disadvantageous nature of their decisions.”

The finding corroborates an idea studied by the paper’s first author, Erik Asp, who wondered why damage to the prefrontal cortex would impair the ability to doubt but not the initial belief as well. Asp created a model, which he called the False Tagging Theory, to separate the two notions and confirm that doubt is housed in the prefrontal cortex.

“This study is strong empirical evidence suggesting that the False Tagging Theory is correct,” says Asp, who earned his doctorate in neuroscience from the UI in May and is now at the University of Chicago.

Kenneth Manzel, Bryan Koestner, and Catherine Cole from the UI are contributing authors on the paper. The National Institute on Aging and the National Institute of Neurological Disorders and Stroke funded the research.

 


Story Source:

The above story is reprinted from materials provided byUniversity of Iowa. The original article was written by Richard C. Lewis.


Journal Reference:

  1. Erik Asp, Kenneth Manzel, Bryan Koestner, Catherine A. Cole, Natalie L. Denburg, Daniel Tranel. A Neuropsychological Test of Belief and Doubt: Damage to Ventromedial Prefrontal Cortex Increases Credulity for Misleading AdvertisingFrontiers in Neuroscience, 2012; 6 DOI: 10.3389/fnins.2012.00100
Citation:

University of Iowa (2012, August 16). Why are elderly duped? Area in brain where doubt arises changes with age. ScienceDaily. Retrieved August 19, 2012, from http://www.sciencedaily.com/releases/2012/08/120816121836.htm

A Pack of Walnuts a Day Keeps the Fertility Specialist Away?

ScienceDaily (Aug. 15, 2012) — A paper published Aug. 15 in Biology of Reproduction‘s Papers-in-Press reveals that eating 75 grams of walnuts a day improves the vitality, motility, and morphology of sperm in healthy men aged 21 to 35.

Approximately 70 million couples experience subfertility or infertility worldwide, with 30 to 50 percent of these cases attributable to the male partner. Some studies have suggested that human semen quality has declined in industrialized nations, possibly due to pollution, poor lifestyle habits, and/or an increasingly Western-style diet.

Dr. Wendie Robbins and her colleagues at the University of California, Los Angeles decided to investigate whether increasing polyunsaturated fatty acids (PUFAs), which are critical for sperm maturation and membrane function, would increase sperm quality in men consuming a Western-style diet.

The best sources of dietary PUFAs in a Western-style diet include fish and fish oil supplements, flax seed, and walnuts, the latter of which are rich sources of α-linolenic acid (ALA), a natural plant source of omega-3.

With support by the California Walnut Commission, Dr. Robbins’ team selected 117 healthy men between the ages of 21 and 35 who ate a Western-style diet and split them into two groups: one (58 men) who would avoid eating tree nuts and another (59 men) who would eat 75 grams of walnuts per day. Previous studies had indicated that 75 grams of walnuts would be a dose at which blood lipid levels would change, but at which healthy young men would not gain weight.

Before the experiment began and then again 12 weeks later, the men’s semen quality was analyzed according to conventional parameters of male fertility, including sperm concentration, vitality, motility, morphology, and chromosome abnormalities.

After 12 weeks, the team found no significant changes in body-mass index, body weight, or activity level in either group. The men consuming walnuts, however, had significantly increased levels of omega-6 and omega-3 (ALA) fatty acids and experienced improvement in sperm vitality, motility, and morphology. Those eating walnuts also had fewer chromosomal abnormalities in their sperm following the walnut dietary intervention. The control group, on the other hand, experienced no changes.

Although this research indicates that eating 75 grams of walnuts per day can positively affect a young man’s sperm quality, it is still unknown whether the benefits would apply to young men with fertility problems and whether they would actually translate into increased fertility.


Story Source:

The above story is reprinted from materials provided bySociety for the Study of Reproduction. 


Journal Reference:

  1. Robbins WA, Xun L, FitzGerald LZ, Esguerra S, Henning SM, Carpenter CL. Walnuts improve semen quality in men consuming a Western-style diet: randomized control dietary intervention trialBiology of Reproduction, 2012; (in press) DOI:10.1095/biolreprod.112.101634
Citation:

Society for the Study of Reproduction (2012, August 15). A pack of walnuts a day keeps the fertility specialist away?. ScienceDaily. Retrieved August 19, 2012, from http://www.sciencedaily.com/releases/2012/08/120815151610.htm

Previously Unknown Cleaning System in Brain: Newer Imaging Technique Brings ‘Glymphatic System’ to Light

ScienceDaily (Aug. 15, 2012) — A previously unrecognized system that drains waste from the brain at a rapid clip has been discovered by neuroscientists at the University of Rochester Medical Center. The findings were published online August 15 in Science Translational Medicine.

An artery in the brain of a mouse. The green shows cerebrospinal fluid in a channel along the outside of the artery. (Credit: Image courtesy of University of Rochester Medical Center)

The highly organized system acts like a series of pipes that piggyback on the brain’s blood vessels, sort of a shadow plumbing system that seems to serve much the same function in the brain as the lymph system does in the rest of the body — to drain away waste products.

“Waste clearance is of central importance to every organ, and there have been long-standing questions about how the brain gets rid of its waste,” said Maiken Nedergaard, M.D., D.M.Sc., senior author of the paper and co-director of the University’s Center for Translational Neuromedicine. “This work shows that the brain is cleansing itself in a more organized way and on a much larger scale than has been realized previously.

“We’re hopeful that these findings have implications for many conditions that involve the brain, such as traumatic brain injury, Alzheimer’s disease, stroke, and Parkinson’s disease,” she added.

Nedergaard’s team has dubbed the new system “the glymphatic system,” since it acts much like the lymphatic system but is managed by brain cells known as glial cells. The team made the findings in mice, whose brains are remarkably similar to the human brain.

Scientists have known that cerebrospinal fluid or CSF plays an important role cleansing brain tissue, carrying away waste products and carrying nutrients to brain tissue through a process known as diffusion. The newly discovered system circulates CSF to every corner of the brain much more efficiently, through what scientists call bulk flow or convection.

“It’s as if the brain has two garbage haulers — a slow one that we’ve known about, and a fast one that we’ve just met,” said Nedergaard. “Given the high rate of metabolism in the brain, and its exquisite sensitivity, it’s not surprising that its mechanisms to rid itself of waste are more specialized and extensive than previously realized.”

While the previously discovered system works more like a trickle, percolating CSF through brain tissue, the new system is under pressure, pushing large volumes of CSF through the brain each day to carry waste away more forcefully.

The glymphatic system is like a layer of piping that surrounds the brain’s existing blood vessels. The team found that glial cells called astrocytes use projections known as “end feet” to form a network of conduits around the outsides of arteries and veins inside the brain — similar to the way a canopy of tree branches along a well-wooded street might create a sort of channel above the roadway.

Those end feet are filled with structures known as water channels or aquaporins, which move CSF through the brain. The team found that CSF is pumped into the brain along the channels that surround arteries, then washes through brain tissue before collecting in channels around veins and draining from the brain.

How has this system eluded the notice of scientists up to now?

The scientists say the system operates only when it’s intact and operating in the living brain, making it very difficult to study for earlier scientists who could not directly visualize CSF flow in a live animal, and often had to study sections of brain tissue that had already died. To study the living, whole brain, the team used a technology known as two-photon microscopy, which allows scientists to look at the flow of blood, CSF and other substances in the brain of a living animal.

While a few scientists two or three decades ago hypothesized that CSF flow in the brain is more extensive than has been realized, they were unable to prove it because the technology to look at the system in a living animal did not exist at that time.

“It’s a hydraulic system,” said Nedergaard. “Once you open it, you break the connections, and it cannot be studied. We are lucky enough to have technology now that allows us to study the system intact, to see it in operation.”

First author Jeffrey Iliff, Ph.D., a research assistant professor in the Nedergaard lab, took an in-depth look at amyloid beta, the protein that accumulates in the brain of patients with Alzheimer’s disease. He found that more than half the amyloid removed from the brain of a mouse under normal conditions is removed via the glymphatic system.

“Understanding how the brain copes with waste is critical. In every organ, waste clearance is as basic an issue as how nutrients are delivered. In the brain, it’s an especially interesting subject, because in essentially all neurodegenerative diseases, including Alzheimer’s disease, protein waste accumulates and eventually suffocates and kills the neuronal network of the brain,” said Iliff.

“If the glymphatic system fails to cleanse the brain as it is meant to, either as a consequence of normal aging, or in response to brain injury, waste may begin to accumulate in the brain. This may be what is happening with amyloid deposits in Alzheimer’s disease,” said Iliff. “Perhaps increasing the activity of the glymphatic system might help prevent amyloid deposition from building up or could offer a new way to clean out buildups of the material in established Alzheimer’s disease,” he added.

In addition to Iliff and Nedergaard, other authors from Rochester include Minghuan Wang, Yonghong Liao, Benjamin Plogg, Weiguo Peng, Edward Vates, Rashid Deane, and Steven Goldman. Also contributing were Erlend Nagelhus and Georg Gundersen of the University of Oslo, and Helene Benveniste of the Health Science Center at Stony Brook University.

The work was funded by the National Institutes of Health (grant numbers R01NS078304 and R01NS078167), the U.S. Department of Defense, and the Harold and Leila Y. Mathers Charitable Foundation.

 


Story Source:

The above story is reprinted from materials provided byUniversity of Rochester Medical Center.


Journal Reference:

  1. Jeffrey J. Iliff, Minghuan Wang, Yonghong Liao, Benjamin A. Plogg, Weiguo Peng, Georg A. Gundersen, Helene Benveniste, G. Edward Vates, Rashid Deane, Steven A. Goldman, Erlend A. Nagelhus, and Maiken Nedergaard. A Paravascular Pathway Facilitates CSF Flow Through the Brain Parenchyma and the Clearance of Interstitial Solutes, Including Amyloid βScience Translational Medicine, 2012; DOI: 10.1126/scitranslmed.3003748
Citation:

University of Rochester Medical Center (2012, August 15). Previously unknown cleaning system in brain: Newer imaging technique brings ‘glymphatic system’ to light.ScienceDaily. Retrieved August 19, 2012, from http://www.sciencedaily.com/releases/2012/08/120815142042.htm