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About Egghead

Egghead is a blog about research by, with or related to UC Davis. Comments on posts are welcome, as are tips and suggestions for posts. General feedback may be sent to Andy Fell. This blog is created and maintained by UC Davis University Communications, and mostly edited by Andy Fell.

Curiosity helps learning and memory

Curiosity helps us learn about a topic, and being in a curious state also helps the brain memorize unrelated information, according to researchers at the UC Davis Center for Neuroscience. Work published Oct. 2 in the journal Neuron provides insight into how piquing our curiosity changes our brains, and could help scientists find ways to enhance overall learning and memory in both healthy individuals and those with neurological conditions.

“Our findings potentially have far-reaching implications for the public because they reveal insights into how a form of intrinsic motivation — curiosity — affects memory. These findings suggest ways to enhance learning in the classroom and other settings,” says first author Matthias Gruber, a postdoctoral researcher at the center.

Video: How curiosity changes the brain and enhances learning

Participants in the study first rated their curiosity about the answers to a series of trivia questions. Later, they had their brains scanned via functional magnetic resonance imaging while they learned the answers to these questions. First, they were presented with a selected trivia question and while they waited for the answer to pop up on the screen, they were shown a picture of a neutral, unrelated face.

Afterwards, participants performed a surprise recognition memory test for the presented faces, followed by a memory test for the answers to the trivia questions.

As might be expected, people were better at learning the trivia information when they were highly curious about it. More surprisingly, they also showed better learning of the unrelated faces that were shown while their curiosity was aroused. Information learned during a curious state was better retained over a 24-hour delay.

“Curiosity may put the brain in a state that allows it to learn and retain any kind of information, like a vortex that sucks in what you are motivated to learn, and also everything around it,” Gruber said.

Secondly, the investigators found that when curiosity is stimulated, there is increased activity in the brain circuit related to reward.

“We showed that intrinsic motivation actually recruits some of the same brain areas that are heavily involved in tangible, extrinsic motivation,” Gruber said. This reward circuit relies on dopamine, a chemical that relays messages between neurons.

The team also discovered that when learning was motivated by curiosity, there was increased activity in the hippocampus, a brain region that is important for forming new memories, as well as increased interactions between the hippocampus and the dopamine reward circuit.

Charan Ranganath is exploring the basis of memory.

Charan Ranganath is exploring the basis of memory.

“So curiosity recruits the reward system, and interactions between the reward system and the hippocampus seem to put the brain in a state in which you are more likely to learn and retain information, even if that information is not of particular interest or importance,” said Charan Ranganath, senior author, and Professor at the UC Davis Center for Neuroscience and Department of Psychology.

Brain circuits that rely on dopamine tend to decline in function with aging, or sooner in people with neurological or psychiatric disorders. Understanding the relationship between motivation and memory could stimulate new efforts to improve memory in the healthy elderly and new approaches for treating patients with memory disorders. And in the classroom or workplace, learning could be enhanced if teachers or managers can engage students’ and workers’ curiosity about something they are naturally motivated to learn.

Coauthors on the study were Gruber, Ranganath and research scientist Bernard Gelman. The work was supported by the National Institutes of Health, the Simon J. Guggenheim Foundation, and the Leverhulme Trust.

Dust to dust: BICEP2 result on gravitational waves may not be so strong

Earlier this year, physicists celebrated results from the BICEP2 experiment which reported evidence of gravitational waves, a signature of cosmic inflation immediately after the Big Bang.

But earlier this week, results from the Planck space telescope cast doubt on the BICEP2 findings. Instead of showing gravitational waves at the beginning of time, BICEP2 might actually have picked up interstellar dust within our own galaxy.

Andy Albrecht, a UC Davis physics professor and well-known theorist on cosmic inflation, wrote this blog post reflecting on the “emotional roller coaster” of the BICEP2 and Planck findings. The lack of a gravitational signal at the level detectable by BICEP2 does not rule out cosmic inflation, because there are models that include a weaker signal, he wrote. But the story “has given people a wonderful window on the emotional energy that goes into doing science,” he wrote.

This is certainly a story about the passion that goes into doing science, but it is also a success story for science. While I do feel the BICEP2 team should have been more careful about how they presented their results, their over-optimistic beliefs about the limited impact of galactic dust on their data reflected a (mistaken) perspective that was widely held in our community regarding the overall strength of the dust emissions. The relentless march of progress is clearing up these misconceptions, and progress was in fact stimulated by the excitement surrounding the original announcement.

Interestingly, UC Davis physicist Lloyd Knox noted in a blog post at the time of the original result that he was concerned about contamination from interstellar dust.

Grant to help commercialize silicon surgical blades

A UC Davis engineering professor has received a grant of $200,000 from the National Science Foundation “Partnerships for Innovation: Accelerating Innovation Research- Technology Translation” program to move his silicon-based blades towards commercial development as surgical and shaving tools.

Silicon or ceramic blades are extremely sharp and hard, keeping an edge longer than metal blades, but they are expensive to manufacture. The technique recently invented by Saif Islam, professor of electrical and computer engineering at UC Davis, allows thin silicon blades to be mass-produced at much lower cost.

Islam and his team stumbled on the technique while making silicon wafers for research on solar panels. They produced some very thin vertical walls of silicon, which turned out to be extremely sharp.

Islam has formed a company, Atocera (formerly Nano-Sharp) to license the patented technology from UC Davis and take it into commercial development. The grant will support development of a plan for scaling up the process for making silicon surgical blades.

Using silicon opens possibilities for “smart” blades, Islam said.

“Potentially, we could incorporate electrical and optical technologies, taking advantage of the semiconductor platform, to facilitate an enhanced hair removal process,” he said.

Atocera is currently housed in the Engineering Translational Technology Center, the business incubator in the UC Davis College of Engineering. The company’s Interim CEO is Jim Olson, the center’s business specialist and co-founder. The work has previously been supported by a Proof of Concept grant from the University of California Office of the President (UCOP).

Baby desert tortoises get a headstart in the Mojave

A baby desert tortoise lies on its back atop a scale inside a new building at Mojave National Preserve. It wriggles—slowly­—its arms and feet like an infant on a changing table.

The site, the Ivanpah Desert Tortoise Research Facility, is designed to give struggling desert tortoises like this one a headstart on survival. Located on the preserve itself, researchers from the University of California, Davis and the University of Georgia, will use the facility to research juvenile tortoise survival.

Desert tortoises are tough. They can flourish in places most species find inhospitable. Able to store water for use during a drought, they can go a year without water. Yet habitat loss and other disturbances have threatened their existence, and they are now federally listed as a threatened species.

“The Mojave desert tortoise population has been declining for decades due to loss of habitat, deaths on roadways, disease, and other factors,” said Brian Todd, an associate professor of wildlife biology at UC Davis. “We are excited that our partnership with the National Park Service’s Mojave National Preserve will allow us to study how these factors affect tortoises.”

The facility was built in 2012 by Chevron on Molycorp land and managed until recently by National Park Trust. A dedication ceremony in early September commemorated the transfer of the facility to Mojave National Preserve.

The Desert Tortoise Research Facility includes a LEED Silver-certified laboratory building, two acres of predator-proof tortoise enclosures containing native vegetation, and seven acres of high-quality tortoise habitat. This enables scientists to study them in a protected but natural environment.

Since the facility opened, 185 desert tortoise hatchlings have emerged within the protected facility and 46 have been released and are being monitored.

By raising juvenile tortoises to a larger size and releasing them in the preserve, the scientists expect they can both improve populations of the desert tortoise as well as study survival and behavior of young tortoises, something Todd said was otherwise not possible.

“This new facility provides scientists the opportunity to test methods for increasing the survival of juvenile tortoises to reproductive age,” said Stephanie Dubois, superintendent of Mojave National Preserve. “This research could lead to the development of proven methods for recovering this species that continues to decline.”

Contributed by Kat Kerlin

Psychologist’s research supports gay marriage decision

When a panel of the 7th Circuit Court of Appeals struck down gay marriage bans in Wisconsin and Indiana this week, the justices cited work by UC Davis professor of psychology Gregory Herek.

In the 40-page opinion, Judge Richard A. Posner wrote, “…there is little doubt that sexual orientation, the ground of the discrimination, is an immutable (and probably an innate, in the sense of in-born) characteristic rather than a choice.” Posner cited a paper published by Herek and colleagues in 2010, which found that 95 percent of gay men and 84 percent of lesbians perceived they had little or no choice about their sexual orientation.

About 20 federal courts have now ruled against state laws that ban gay marriage, or ban recognition of out-of-state same-sex marriages, while one U.S. district court has upheld a state ban, so it’s likely the issue will soon be heard by the Supreme Court.


Climate-smart agriculture requires three-pronged global research agenda

Faced with climate change and diminishing opportunities to expand productive agricultural acreage, the world needs to invest in a global research agenda addressing farm and food systems, landscape and regional issues and institutional and policy matters if it is to meet the growing worldwide demand for food, fiber and fuel, suggests an international team of researchers.

In a paper appearing online in the journal Agriculture and Food Security, the authors summarize the findings of the second international Climate Smart Agriculture conference held in March 2013 at UC Davis.

“Climate-smart agriculture has become a global policy initiative for economic development, poverty reduction and food security,” says lead author Kerri Steenwerth, a U.S. Department of Agriculture soil scientist and adjunct professor in the UC Davis Department of Viticulture and Enology.

“It makes sense for farmers, consumers and food businesses because it is focused on the long-term sustainability of supply chains, and applies both to farmers’ fields and to the natural landscape,” she said.

The objectives recommended in the new paper set the stage for a stronger emphasis on moving knowledge into action and involving researchers in helping communities and societies to change and adapt.

Steenwerth has posted a blog entry about the paper on the Biomed Central blog. The blog and the paper were supported by the UC Davis College of Agricultural and Environmental Sciences.

A third global science conference on Climate-Smart Agriculture is scheduled to be held March 16-18, 2015 in Montpellier, France.

The other authors on the paper from UC Davis were: Louise Jackson, Amanda Hodson, Arnold Bloom, Michael Carter, Jan Hopmans, William Horwath, Bryan Jenkins, Ermias Kebreab, Mark Lubell, Samuel Sandoval Solis, Michael Springborn, Stephen Wheeler, and Lovell Jarvis.

Authors representing other institutions were Andrea Cattaneo and Leslie Lipper, both of the Food and Agriculture Organization of the United Nations in Rome, Italy; Colin Chartres of the University of Canberra in Australia; Jerry Hatfield of the ARS/USDA National Laboratory for Agriculture and the Environment in Ames, Iowa; Kevin Henry of Colorado State University; Rik Leemans and Pablo Tittonell, both of Wageningen University, the Netherlands; Siwa Msangi of the International Food Policy Research Institute in Washington, D.C.; Ravi Prabhu of the World Agroforestry Center in Nairobi, Kenya; Matthew Reynolds of the Consultative Group on International Agricultural Research in Mexico; William Sischo of Washington State University; Sonja Vermeulen of the University of Copenhagen, Denmark; and Eva Wollenberg of the Consultative Group on International Agricultural Research (CGIAR).

Watching the structure of glass under pressure

Glass has many applications that call for different properties, such as resistance to thermal shock or to chemically harsh environments. Glassmakers commonly use additives such as boron oxide to tweak these properties by changing the atomic structure of glass. Now researchers at the University of California, Davis, have for the first time captured atoms in borosilicate glass flipping from one structure to another as it is placed under high pressure.

The findings may have implications for understanding how glasses and similar “amorphous” materials respond at the atomic scale under stress, said Sabyasachi Sen, professor of materials science at UC Davis. Sen is senior author on a paper describing the work published Aug. 29 in the journal Science.

Boron oxide is often added to glass to control a range of properties, including chemical durability, flow resistance, optical transparency and thermal expansion. Material scientists know that the structure around the boron atoms in borosilicate glass changes with pressure and temperature, switching from a flat triangular configuration with three oxygen atoms surrounding one boron atom to a four-sided tetrahedron, with four oxygen atoms surrounding one boron.

As borosilicate glass is put under pressure, the structure of boron oxide changes from triangular to tetrahedral through a pyramid-shaped intermediate.

As borosilicate glass is put under pressure, the structure of boron oxide changes from triangular to tetrahedral through a pyramid-shaped intermediate.

Until know, material scientists have only been able to study these structures in one state or the other, but not in transition. Sen and graduate student Trenton Edwards developed a probe that enabled them to make nuclear magnetic resonance (NMR) measurements of the environment of boron atoms in glass under pressures up to 2.5 Gigapascal.

They found that under pressure, the flat triangles of boron and three oxygen atoms first deform into a pyramid shape, with the boron atom pushed up. That may bring it close to another oxygen atom, and let the structure turn into a tetrahedron, with four oxygen atoms surrounding one boron.

Intriguingly, although glass is structurally isotropic and the stress on the glass is the same in all directions, the boron atoms respond by moving in one direction in relation to the rest of the structure.

“This is an unexpected finding that may have far-reaching implications for understanding a wide range of stress-induced phenomena in amorphous materials,” Sen said.

The work was done in collaboration with Jeffrey Walton, project scientist with the UC Davis NMR Facility. It was funded by the U.S. National Science Foundation.

More information: Perspective article from Randall Youngman of Corning, Inc.

Protein is key to forming short-term memories

Synapses from the brainstem.

Synapses from the brainstem.

Short-term memory is essential for everyday life — whether remembering a phone number while dialing, carrying on a conversation, or forming the basis of long-term memories. Neuroscientists think that short-term memory is based on changes in both the properties of brain cells and the connections, called synapses, between them.

Now Diasynou Fioravante, formerly of Harvard Medical School and now at the UC Davis Center for Neuroscience, and colleagues have identified a sensor that plays a key role in modifying neurons and synapses to create short-term memories. The work was published Aug. 5 in the journal eLife.

Brain function depends on signals jumping across synapses. When an electrical signal is generated by the cell before the synapse, calcium ions flow into the cell and trigger release of molecules called neurotransmitters which cross the synapse to the next cell, producing an electrical signal. The size of the signal is a measure of synaptic strength.

Synaptic strength can change over both the short-term (tens of seconds) and long-term. A short-term increase in strength called post-tetanic potentiation is thought to underlie formation of short-term memory. It amplifies the signal across the synapse by increasing the amount of neurotransmitter released in response to each electrical impulse, and it is triggered by an increase of calcium in the presynaptic cell.

Protein kinase C (green stain) on synapses (red). Yellow color shows PKC on synapses.

Protein kinase C (green stain) on synapses (red). Yellow color shows PKC on synapses.

Fioravante and colleagues now show that an enzyme called protein kinase C is responsible for this effect. They found that genetically modified mice that lack protein kinase C do not show this short-term potentiation, but that it could be restored by reintroducing the enzyme. A version of protein kinase C that lacks the ability to bind calcium was unable to trigger post-tetanic potentiation.

The work could provide tools to manipulate brain plasticity and study how memories are formed, Fioravante said. It could also eventually provide new ways to improve short-term memory function in patients with memory deficits.

The researchers think that protein kinase C is likely the first of a new class of sensors that make short-term, local modifications to how brain cells work and connect with each other.

Coauthors on the paper are: YunXiang Chu, Arthur de Jong, Pascal Kaeser and Wade Regehr at Harvard Medical School, and Michael Leitges at the University of Oslo. The work was funded by the National Institutes of Health.

Read the full paper online here.

Memory researcher wins Pentagon grant

Congratulations to Professor Charan Ranganath of the UC Davis Center for Neuroscience and Department of Psychology on his selection as a National Security Science and Engineering Faculty Fellow by the U.S. Department of Defense. The five-year, $2.6 million fellowship will support new work on learning and memory in Ranganath’s Dynamic Memory Laboratory at UC Davis.

Charan Ranganath is exploring the basis of memory.

Charan Ranganath is exploring the basis of memory.

The new project aims to connect neural oscillations, which are currently poorly understood, with activity in the cortex and hippocampus, brain regions that are known to be involved in forming and retrieving memories.

The studies could lead to better ways to assess memory function, methods to boost learning (for example in training situations), and to better rehabilitation of soldiers with brain injuries. The work could also contribute to development of brain-computer interfaces.

“NSSEFF grants are highly competitive, attracting the next generation of outstanding scientists and engineers to some of our most challenging scientific issues and opportunities,” said Dr. Robin Staffin, Director for Basic Research for the Department of Defense, in a news release. “The program provides grants to top-tier researchers from U.S. universities to conduct long-term, unclassified, basic research of strategic importance to the Department of Defense.”

Ranganath is one of just 10 Fellows selected for the program this year, and the only neuroscientist. He has previously received a UC Davis Chancellor’s Fellowship and a Guggenheim Fellowship.

More information: About the NSSEFF program

In this video, Ranganath and postdoc Frank Hsieh describe their recent discoveries on how memories are stored by when they occurred.

Stress-tolerant tomato relative sequenced

Domestic tomatoes (left) and three wild relatives. S. pennellii is on the far right.

Domestic tomatoes (left) and three wild relatives. S. pennellii is on the far right.

The genome of Solanum pennellii, a wild relative of the domestic tomato, has been published by an international group of researchers including the labs headed by Professors Neelima Sinha and Julin Maloof at the UC Davis Department of Plant Biology. The new genome information may help breeders produce tastier, more stress-tolerant tomatoes.

The work, published July 27 in the journal Nature Genetics, was lead by Björn Usadel and colleagues at Aachen University in Germany. The UC Davis labs carried out work on the transcriptome of S. pennellii — the RNA molecules that are transcribed from DNA and then translated into proteins — messages written from DNA and taken to other parts of the cell to tell it what to do. Analyzing the RNA transcriptome shows which genes are active under different circumstances. The UC Davis team published a paper last year comparing the RNA transcripts of domestic tomato and three wild relatives, including S. pennellii.

S. pennellii is inedible, but it can be interbred with domestic tomatoes to introduce useful traits, such as drought resistance.  Using the new genome data, the researchers found genes related to dehydration resistance, fruit development and fruit ripening. They also found genes that contribute to volatile compounds related to fruit scent and flavor.

The UC Davis portion of the work was supported by a grant from the National Science Foundation.

More information:

UC Davis Charles M. Rick Tomato Genetics Resource Center

The Tomato Anatomy Atlas