Author: Théophile Niyitegeka

{Students learn more effectively between 11 a.m. and 9:30 p.m. than at other times of the day}

A new cognitive research study used two new approaches to determine ranges of start times that optimize functioning for undergraduate students. Based on a sample of first and second year university students, the University of Nevada, Reno and The Open University in the United Kingdom used a survey-based, empirical model and a neuroscience-based, theoretical model to analyse the learning patterns of each student to determine optimum times when cognitive performance can be expected to be at its peak.

“The basic thrust is that the best times of day for learning for college-age students are later than standard class hours begin,” Mariah Evans, associate professor of sociology at the University of Nevada, Reno and co-author of the study, said. “Especially for freshmen and sophomores, we should be running more afternoon and evening classes as part of the standard curriculum.”

Prior research has demonstrated that late starts are optimal for most high school students, and this study extends that analysis to freshmen and sophomores in college. The analysis by Evans, Jonathan Kelley, fellow University sociology professor, and Paul Kelley, honorary associate of sleep, circadian and memory neuroscience at The Open University, assessed the preferred sleeping times of the participants and asked them to rate their fitness for cognitive activities in each hour of the 24-hour day.

“Neuroscientists have documented the time shift using biological data — on average, teens’ biologically ‘natural’ day begins about two hours later than is optimal for prime age adults,” Evans said. “The survey we present here support that for college students, but they also show that when it comes to optimal performance, no one time fits all.”

The study showed that much later starting times of after 11 a.m. or noon, result in the best learning. It also revealed that those who saw themselves as “evening” people outnumbered the “morning” people by 2:1, and it concluded that every start time disadvantages one or more of the chronotypes (propensity for the individual to be alert and cognitively active at a particular time during a 24-hour period).

“Thus, the science supports recent moves by the University to encourage evening classes as part of the standard undergraduate curriculum,” Evans said. “It also supports increasing the availability of asynchronous online classes to enable students to align their academic work times with their optimal learning times.”

The results, Identifying the best times for cognitive functioning using new methods: Matching university times to undergraduate chronotypes, were published in Frontiers in Human Neuroscience March 31, 2017.

“This raises the question as to why conventional universities start their lectures at 9 a.m. or even earlier when our research reveals that this limits the performance of their students,” Kelley said. “This work is very helpful for asynchronous online learning as it allows for the student to target their study time to align with their personal rhythm and at the time of day when they know they are most effective.”

Source:Science Daily

{World’s first sustainable, industrial-scale agriculture began when crops became dependent on their ant farmers}

Millions of years before humans discovered agriculture, vast farming systems were thriving beneath the surface of the Earth. The subterranean farms, which produced various types of fungi, were cultivated and maintained by colonies of ants, whose descendants continue practicing agriculture today.

By tracing the evolutionary history of these fungus-farming ants, scientists at the Smithsonian’s National Museum of Natural History have learned about a key transition in the insects’ agricultural evolution. This transition allowed the ants to achieve higher levels of complexity in farming, rivaling the agricultural practices of humans: the domestication of crops that became permanently isolated from their wild habitats and thereby grew dependent on their farmers for their evolution and survival.

In the April 12 issue of Proceedings of Royal Society B, scientists led by entomologist Ted Schultz, the museum’s curator of ants, report that the transition likely occurred when farming ants began living in dry climates, where moisture-loving fungi could not survive on their own. The finding comes from a genetic analysis that charts the evolutionary relationships of farming and non-farming ants from wet and dry habitats throughout the Neotropics.

About 250 species of fungus-farming ants have been found in tropical forests, deserts and grasslands in the Americas and the Caribbean, and these species fall into two different groups based on the level of complexity of their farming societies: lower and higher agriculture. All farming ants start new fungal gardens when a queen’s daughter leaves her mother’s nest to go off and found her own nest, taking with her a piece of the original colony’s fungus to start the next colony’s farm.

In the lower, primitive forms of ant agriculture — which largely occur in wet rain forests — fungal crops occasionally escape from their ant colonies and return to the wild. Lower ants also occasionally regather their farmed fungi from the wild and bring them back to their nests to replace faltering crops. These processes allow wild and cultivated fungi to interbreed and limit the degree of influence the lower ants have over the evolution of their crops.

vBut, as with certain crops that have been so heavily modified by human breeders that they can no longer reproduce and live on their own in the wild, some fungal species have become so completely dependent on their relationship with farming ants that they are never found living independent of their farmers. These higher agricultural ants cultivate highly “domesticated” crops, enabling them to live in vast communities and to work together through division of labor to fertilize their fungal crops, haul away waste, keep pathogens at bay and maintain ideal growing conditions.

“These higher agricultural-ant societies have been practicing sustainable, industrial-scale agriculture for millions of years,” Schultz said. “Studying their dynamics and how their relationships with their fungal partners have evolved may offer important lessons to inform our own challenges with our agricultural practices. Ants have established a form of agriculture that provides all the nourishment needed for their societies using a single crop that is resistant to disease, pests and droughts at a scale and level of efficiency that rivals human agriculture.”

Today, many agricultural ant species are threatened by habitat destruction, and as part of his studies, Schultz has been collecting specimens from the field and preserving them in the museum’s cryogenic biorepository for future genomic studies. In the current study, he and his colleagues compared the genomes of 119 modern ant species, most of which were collected during his decades of field expeditions.

Using powerful new genomic tools, the scientists compared DNA sequences at each of more than 1,500 genome sites for 78 fungus-farming species and 41 non-fungus-farming species. Their data-rich analysis gave the team a great deal of confidence in the evolutionary relationships they were able to map, Schultz said.

Their analysis clarifies the closest living non-farming relative of today’s fungus-growing ants and allows Schultz and his team to begin to look at the geographic backgrounds of these species and deduce when, where and under what conditions particular traits emerged. In this study, the team was interested in learning when ants began practicing higher agriculture — that is, when some fungal crops came to be dependent on the ant-fungus relationship for survival.

According to the evolutionary tree they constructed, the first ants to transition to higher agriculture likely lived in a dry or seasonally dry climate. The transition appears to have occurred around 30 million years ago — a time when the planet was cooling, and dry areas were becoming more prevalent.

Fungi that had evolved to live in wet forests would have been poorly equipped to survive independently in this changing climate. “But if your ant farmer evolves to be better at living in a dry habitat, and it brings you along and it sees to all your needs, then you’re going to be doing okay,” Schultz said.

Just as humans living in a dry or temperate climate might raise tropical plants in a greenhouse, agricultural ants carefully maintain the humidity within their fungal gardens. “If things are getting a little too dry, the ants go out and get water and they add it,” Schultz said. “If they’re too wet, they do the opposite.” So even when conditions above the surface become inhospitable, fungi can thrive inside the underground, climate-controlled chambers of an agricultural ant colony.

In this situation, fungi can become dependent on their ant farmers — unable to escape the nest and return to the wild. “If you’ve been carried into a dry habitat, your fate is going to match the fate of the colony you’re in,” Schultz said. “At that point, you’re bound in a relationship with those ants that you were not bound in when you were in a wet forest.”

Schultz said the conditions present during this evolutionary transition illustrate how an organism can become domesticated even if its farmers are not consciously selecting for desirable traits as human breeders might do. Ants that moved their fungi into new habitats would have isolated the organism from its wild relatives, just as humans do when they domesticate a crop. This isolation creates an opportunity for the farmed species to evolve independently from species in the wild, adopting new traits.

Funding for this study was provided by the Smithsonian and the National Science Foundation.

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Source:Science Daily

{A new study led by scientists at The Scripps Research Institute (TSRI) could help researchers develop personalized treatments for alcoholism and alcohol use disorder.}

The research reveals a key difference between the brains of alcohol-dependent versus nondependent rats. When given alcohol, both groups showed increased activity in a region of the brain called the central amygdala (CeA) — but this activity was due to two completely different brain signaling pathways.

TSRI Professor Marisa Roberto, senior author of the new study, said the findings could help researchers develop more personalized treatments for alcohol dependence, as they evaluate how a person’s brain responds to different therapeutics.

The findings were published recently online ahead of print in The Journal of Neuroscience.

{{Researchers Find Brain’s Alcohol Response ‘Switch’}}

The new research builds on the Roberto lab’s previous discovery that alcohol increases neuronal activity in the CeA. The researchers found increased activity both nondependent, or naïve, and alcohol-dependent rats.

As they investigated this phenomenon in the new study, Roberto and her colleagues were surprised to find that the mechanisms underlying this increased activity differed between the two groups.

By giving naïve rats a dose of alcohol, the researchers engaged proteins called calcium channels and increased neuronal activity. Neurons fired as the specific calcium channels at play, called L-type voltage-gated calcium channels (LTCCs), boosted the release of a neurotransmitter called GABA. Blocking these LTCCs reduced voluntary alcohol consumption in naïve rats.

But in alcohol-dependent rats, the researchers found decreased abundance of LTCCs on neuronal cell membranes, disrupting their normal ability to drive a dose of alcohol’s effects on CeA activity. Instead, increased neuronal activity was driven by a stress hormone called corticotropin-releasing factor (CRF) and its type 1 receptor (CRF1). The researchers found that blocking CeA CRF1s reduced voluntary alcohol consumption in the dependent rats.

Studying these two groups shed light on how alcohol functionally alters the brain, Roberto explained.

“There is a switch in the molecular mechanisms underlying the CeA’s response to alcohol (from LTCC- to CRF1-driven) as the individual transitions to the alcohol-dependent state,” she said.

The cellular and molecular experiments were led by TSRI Research Associate and study first author Florence Varodayan. The behavioral tests were conducted by TSRI Research Associate Giordano de Guglielmo in the lab of TSRI Associate Professor Olivier George.

Roberto hopes the findings lead to better ways to treat alcohol dependence. Alcohol use disorder appears to have many different root causes, but the new findings suggest doctors could analyze certain symptoms or genetic markers to determine which patients are likely to have CRF-CRF1 hyperactivation and benefit from the development of a novel drug that blocks that activity.

Source:Science Daily