It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Saturday, July 24, 2021
The impact of climate change on Kenya's Tana river basin
Many species within Kenya's Tana River Basin will be unable to survive if global temperatures continue to rise as they are on track to do - according to new research from the University of East Anglia.
A new study published in the journal PLOS ONE today outlines how remaining within the goals of the Paris Agreement would save many species.
The research also identifies places that could be restored to better protect biodiversity and contribute towards global ecosystem restoration targets.
Researcher Rhosanna Jenkins carried out the study as part of her PhD at UEA's School of Environmental Sciences.
She said: "This research shows how many species within Kenya's Tana River Basin will be unable to survive if global temperatures continue to rise as they are on track to do.
"But remaining within the goals of the Paris Agreement, which aims to keep global warming well below 2°C, ideally at 1.5°C, would save many species. This is because large areas of the basin act as refugia from climate change."
"With higher warming levels, not only are the refuges lost but also the potential for restoration becomes more limited.
"The United Nations declared the 2020s as the 'Decade on Ecosystem Restoration'. Our results show the importance of considering climate change within these restoration efforts.
"With higher levels of warming, many of the species you are trying to restore will no longer be able to survive in the places they were originally found.
"Strong commitments from global leaders ahead of the COP climate change summit in Glasgow are needed to stand any chance of avoiding the loss of species - which for the Tana River Basin is clearly indicated by this work."
###
'Addressing risks to biodiversity arising from a changing climate: the need 2 for ecosystem restoration in the Tana River Basin, Kenya' is published in the journal PLOS ONE on July 21, 2021.
What's riskier for young soccer players, practice or game time?
On average, impacts are more frequent during drills, more severe during games
For young soccer players, participating in repetitive technical training activities involving heading during practice may result in more total head impacts but playing in scrimmages or actual soccer games may result in greater magnitude head impacts. That's according to a small, preliminary study released today that will be presented at the American Academy of Neurology's Sports Concussion Conference, July 30-31, 2021.
"Headers are a fundamental component to the sport of soccer. Therefore, it is important to understand differences in header frequency and magnitude across practice and game settings," said study author Jillian Urban, PhD, MPH, of Wake Forest School of Medicine in Winston-Salem, N.C. "Practices are more amenable to change than games. Therefore, understanding how we can restructure practice to reduce head impact exposure while teaching fundamental skills needed to safely play the sport is critical to improving head impact safety in the sport."
The study followed eight soccer players who were ages 14 and 15 for two seasons. Players wore a custom-fitted mouthpiece sensor during all practices and games. Researchers recorded all activities on the field with a time-synchronized camera, and identified each time head contact was made.
Head impact exposure was quantified in terms of peak head motion and impacts per player per hour, or impact rate. The amount of time an athlete was exposed to an activity was also evaluated. Researchers then compared impact rates across activity types which ranged from 0.5 head impacts per player hour to 13.7 head impacts per player hour.
Researchers saw a similar number of player-to-player contacts happening during technical drills, team interaction and game play. Technical training activities like heading the ball and practicing ball-control and dribbling were associated with an average impact rate of 13.7 head impacts per player hour. Team interaction activities such as small-sided games in practice were associated with an average impact rate of 0.5 head impacts per player per hour, which was slightly lower than the 1.3 head impacts per player hour observed during games.
Researchers also looked at average rotational head motion, which ranged from 500 radians per second squared (rad/s2) to 1,560 rad/s2, with higher numbers signifying greater magnitude head impacts. Technical training was associated with an average magnitude of 550 rad/s2, while team interaction and games were associated with an average rotational head motion of 910 rad/s2 and 1,490 rad/s2, respectively.
"If the goal is to reduce the number of head impacts a young soccer player may get on the field, our findings suggest the best way may be to target technical training drills and how they are distributed within a season," said Urban. "However, if the goal is to reduce the likelihood of players sustaining head impacts of greater magnitude, then the best bet may be to look at factors associated with high-magnitude head impacts that can occur during scrimmages and games."
A limitation of the study is the small number of players involved.
###
The study was supported in part by the Childress Institute for Pediatric Trauma.
Learn more about concussion at BrainandLife.org, home of the American Academy of Neurology's free patient and caregiver magazine focused on the intersection of neurologic disease and brain health. Follow Brain & Life® on Facebook, Twitter and Instagram.
When posting to social media channels about this research, we encourage you to use the hashtags #AANSCC and #AANscience.
The American Academy of Neurology is the world's largest association of neurologists and neuroscience professionals, with over 36,000 members. The AAN is dedicated to promoting the highest quality patient-centered neurologic care. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as Alzheimer's disease, stroke, migraine, multiple sclerosis, concussion, Parkinson's disease and epilepsy.
For more information about the American Academy of Neurology, visit AAN.com or find us on Facebook, Twitter, Instagram, LinkedIn and YouTube.
Disclaimer: AAAS and EurekAlert! are not responsible for the a
Better healthcare management can reduce the riskof delirium among older adults
New research outlines how those admitted on Sunday and Tuesday are more likely to develop delirium, a hospital complication
Elderly patients with neurological conditions are significantly more likely to develop delirium shortly after they are hospitalised.
A new study has discovered that a delayed transfer to a hospital floor is associated with greater short-term risk of delirium among patients aged 65 and over, and for those who arrive to the Emergency Department (ED) on days with higher risk of prolonged lengths of stay - found to be Sunday and Tuesday.
Delirium is an acute cognitive disorder characterised by altered awareness, attentional deficits, confusion, and disorientation. Current estimates of new-onset delirium highlight the fact that delirium overwhelmingly develops in medical settings (as high as 82 per cent in intensive care settings) compared to the community at large (between one per cent and two per cent). Research has shown that between 30 per cent and 40 per cent of all delirium cases are preventable.
Authored by Valdery Moura Junior, an Executive PhD Research student at the Business School (formerly Cass), the study explores whether a combination of the care experienced at the ED and the delayed implementation of delirium prevention measures contribute to an increased risk of the disorder. For example, it is possible that the bright lights and high ambient noise level of the ED for 24 hours a day will contribute to increased short-term risk.
The findings showed that of the 858 patients who presented to the ED with a neurological emergency, delirium was documented in 234 (30 per cent) patients within the first 72 hours from ED arrival.
This study also found that there was a connection between the onset of delirium and the day in which the patient arrived in the ED. Those arriving on Sundays and Tuesdays were more likely to demonstrate symptoms in a shorter time. Casual factors suggested include fewer hospital beds, delayed floor admission - a waiting time greater than 13 hours - and a greater proportion of elective pre-surgical admissions.
Mr. Moura has outlined several measures which can be taken to help prevent the likelihood of the onset of delirium in these settings, as well as reduce spending. These include an earlier initiation of delirium prevention measures; a quicker transfer from the ED to the hospital bed; and improving communication across healthcare managers in primary care, emergency rooms, operating rooms, and post-acute services.
Valdery Moura Junior, who is also computer scientist and technical leader at the Mass General Brigham, a Boston-based non-profit hospital and physicians network that includes Brigham and Women's Hospital (BWH) and Massachusetts General Hospital (MGH), two of the Harvard Medical School's most prestigious teaching hospitals, said:
"New-onset delirium in older patients alone will mean a high price for the health care system and poses a global challenge for healthcare managers, providers, and payors. Managing hospital capacity has been an enormous challenge throughout the pandemic, with many admission processes reviewed as a result with the goal of improving patient outcomes. Our study may help to identify feasible targets to improve processes between ED and the rest of the hospital."
Professor Feng Li, Chair of Information Management at the Business School, said: "This is an excellent example where routine operational data in a hospital can be used to identify anomaly and improve patient outcomes. Valdery's research demonstrated that more systematic use of such data can lead to significant improvement in the management of hospital capacity and operational processes, and most of all, quality of patient care."
1. Although delirium reverberates through all age populations, adults over 65 are at greater risk of developing delirium during an acute illness, as are individuals with an underlying neurocognitive disorder (mild cognitive impairment and dementia)
2. ED arrival on Sundays was associated with delayed floor admission and with the lowest proportion of hospital to skilled nursing facility discharges. Similarly, ED arrival on Tuesdays was associated with delayed floor admission and with greater proportion of elective pre-surgical admissions on Wednesday morning
3. The research examined the time to delirium onset among 858 patients: 2/3 were admitted for stroke, with the remaining admitted for another acute neurologic event. Among all patients, 81.2 per cent had at least one delirium risk factor in addition to age. All eligible patients received delirium prevention protocols upon admission to the floor and received at least one delirium screening event
4. Of the 858 patients aged 65+, 697 (81 per cent) had at least one delirium risk factor (e.g., stroke, visual impairment, fall, dementia)
Policing the digital divide: How racial bias can limit Internet access for people of color
New research shows that the policing of nonviolent offenses, like loitering, restricts access to free Wi-Fi, particularly for people of color
Coffee shops and casual restaurants are an important part of American life. Even beyond the food and drinks they sell, they offer us a place to use the restroom or rest our feet while we're out and about, and they provide internet access to those on the go, those in need of a temporary office, or those who don't have an internet connection at home. Many of us take for granted that a nearby Starbucks or McDonald's can offer us a little respite, even if we don't always make a purchase.
But access to these sorts of quasi-public spaces isn't always equal in America, particularly for Black people and other people of color. One such example of this is the infamous 2018 incident in Philadelphia when two Black men waiting at Starbucks for an acquaintance were arrested for loitering. The national outcry over their biased and unjust treatment led to a change in Starbucks' corporate policy. It also begs the question: how often does this kind of incident happen around the country and what implications does it have?
A new study published in the Journal of Communication from researchers at the Annenberg School for Communication at the University of Pennsylvania investigated the ways that institutions control who has access to Wi-Fi. The findings indicate that powerful institutions and privileged people use quality-of-life policing -- the report and/or arrest of individuals engaged in nonviolent offenses such as loitering, noise violations, and public intoxication -- to keep those with less privilege, including people of color, from accessing resources like the internet.
The inspiration for the study came from a story Professor Julia Ticona heard while interviewing gig workers for her forthcoming book, Left to Our Own Devices: Coping with Insecure Work in a Digital Age (Oxford University Press). One of her interviewees, a 20-year-old Black man named Alex, had a Starbucks manager threaten to call the police on him because he was using an outlet and the internet.
"I was so frustrated for him personally," says Ticona. "And I was also frustrated that we so often talk about the digital divide as a matter of people not being able to afford access, entirely omitting from the discussion that people are actively being threatened for using the internet."
Ticona shared her frustration with Professor Yphtach Lelkes and doctoral candidate Tian Yang, and the three scholars joined forces to develop a method for investigating whether and how institutions are policing access to the internet.
"This paper is a great example of disciplinary cross-fertilization" says Lelkes. "Julia and I have offices across the hall from one another, and Tian was working with me as a research fellow and taking Julia's class at the time. This project came about because Annenberg is such a big tent when it comes to methods and ways of thinking, and the school encourages collaborations between its various scholars."
The researchers analyzed publicly available data to determine whether quality-of-life policing increased, decreased, or remained the same once free Wi-Fi was introduced to restaurants -- namely Burger King, McDonald's, Panera, Starbucks, and Wendy's -- in various neighborhoods in Chicago between 2008 and 2016. They compiled their own dataset for the study, combining crime data from the police department, neighborhood information from the U.S. Census Bureau, and the locations of stores listed on business licenses.
"We were excited to be able to establish a causal relationship between institutional dynamics and their outcomes in perpetuating social inequalities," says Yang. "To do this, we applied methods used in economics and other fields to develop a way to analyze the data for answers to our questions."
The researchers found that wealthier, whiter neighborhoods had a 5% increase in quality-of-life complaints to the police after restaurants began offering internet access, while other neighborhoods did not. They also found that those same wealthy, white neighborhoods did not have an increase in the report of other kinds of crime, like assault or burglary. The researchers believe their findings suggest that economic hurdles aren't the only factor shaping people's internet access, but that active exclusion from public spaces -- where some people are allowed to enjoy Wi-Fi and others aren't -- also contributes to the digital divide.
"This paper connects ongoing conversations about the role of institutions in perpetuating white supremacy and privilege in the digital age to long-standing questions about digital access," says Ticona. "We hope this study can contribute to the efforts to have a different kind of conversation in the field of Communication about the role of policing, race, and class in reinforcing digital inequalities."
###
The study, entitled "Policing the Digital Divide: Institutional Gate-Keeping and Criminalizing Digital Inclusion," was published in the Journal of Communication. Authors include Tian Yang, Julia Ticona, and Yphtach Lelkes.
In some parts of Thoreau's Walden, such a duality is evident. In a language that echoes the sharp dualism of the Christian faith, Thoreau speaks of the transcendental mind "descending" into the natural body to "redeem" it (349). He even finds an inverse ratio between the body and the soul. "The animal in us," says he, "awakens in proportion as our higher nature slumbers." He quotes Mencius to the effect that the difference between man and the brute is very slim. In the raging battle within man, where the human side is pitted against the animal side, ordinary people very soon lose the distinctly human, while "superior men preserve it carefully" (346).
PURE CLASSISM The duality at times turns into a sharp polarity where nature inspires Thoreau's deepest fears, if not his contempt. The Canadian woodchopper, "a simple natural man," (227) was so absorbed in nature that Thoreau painted him as being unable to absorb "the spiritual view of things." To Thoreau, "the highest that he appeared to conceive of was a simple expediency, such as you might except an animal to appreciate" (279).
It is this disdain for nature that led Thoreau in "Higher Laws" to speak with some remorse about the inability to expel "the reptile and sensual" aspects of human nature, drawing analogies from physical nature to communicate his disgust. "It is like the worms, says he, "which, even in life and health, occupy our bodies (346). Hostility and disdain create the desire for radical transcendence which becomes quite pronounced when Thoreau asserts that "nature is hard to overcome but she must be overcome" (348).
Karl Marx and Swami Vivekananda:
It is unknown in India, but Karl Marx and Swami Vivekananda had similar views on the historical cycle of the world. According to Marx the world history has four cycles starting with primitive communism of tribal societies, then feudalism, capitalism and ultimately socialism followed by advanced communism. For Marx the history is deterministic, these cycles are bound to happen due to the contradictions or dialectics in the existing system. In Karl Marx, ”Changes occur in society because of contradictions in prevailing ideology, in its social, economic and political order. These contradictions arise from hostilities between the social classes” (in A Contribution to the Critique of Political Economy, Progress Publishers, Moscow).
Swami Vivekananda similarly divided the world history into four cycles, starting with the Age of the Priests, Age of the Warriors, Age of the Merchants as we are now in and ultimately the Age of the Worker, which is coming. With each cycle, society rises to higher and still higher stages and is perfected.
The contradiction in the society according to Vivekananda is as follows, “.. At a certain time every society attains its manhood, when a strong conflict ensues between the ruling power and the common people” (Vivekananda, Collected Works, vol.iv, p.399).
In the new Age of the Workers, “just distribution of material values will be achieved, equality of the rights of all members of society to ownership of property established and caste differences obliterated” (in Vivekananda, Collected Works, vol.vi, p.343). Sri Aurobindo also has expressed similar views on history.
Blushing plants reveal when fungi are growing in their roots
Almost all crop plants form associations with a particular type of fungi - called arbuscular mycorrhiza fungi - in the soil, which greatly expand their root surface area. This mutually beneficial interaction boosts the plant's ability to take up nutrients that are vital for growth.
The more nutrients plants obtain naturally, the less artificial fertilisers are needed. Understanding this natural process, as the first step towards potentially enhancing it, is an ongoing research challenge. Progress is likely to pay huge dividends for agricultural productivity.
In a study published in the journal PLOS Biology, researchers used the bright red pigments of beetroot - called betalains - to visually track soil fungi as they colonised plant roots in a living plant.
"We can now follow how the relationship between the fungi and plant root develops, in real-time, from the moment they come into contact. We previously had no idea about what happened because there was no way to visualise it in a living plant without the use of elaborate microscopy," said Dr Sebastian Schornack, a researcher at the University of Cambridge's Sainsbury Laboratory and joint senior author of the paper.
To achieve their results, the researchers engineered two model plant species - a legume and a tobacco plant - so that they would produce the highly visible betalain pigments when arbuscular mycorrhiza fungi were present in their roots. This involved combining the control regions of two genes activated by mycorrhizal fungi with genes that synthesise red-coloured betalain pigments.
The plants were then grown in a transparent structure so that the root system was visible, and images of the roots could be taken with a flatbed scanner without disturbing the plants.
Using their technique, the researchers could select red pigmented parts of the root system to observe the fungus more closely as it entered individual plant cells and formed elaborate tree-like structures - called arbuscules - which grow inside the plant's roots. Arbuscules take up nutrients from the soil that would otherwise be beyond the reach of the plant.
Other methods exist to visualise this process, but these involve digging up and killing the plant and the use of chemicals or expensive microscopy. This work makes it possible for the first time to watch by eye and with simple imaging how symbiotic fungi start colonising living plant roots, and inhabit parts of the plant root system over time.
"This is an exciting new tool to visualise this, and other, important plant processes. Beetroot pigments are a distinctive colour, so they're very easy to see. They also have the advantage of being natural plant pigments, so they are well tolerated by plants," said Dr Sam Brockington, a researcher in the University of Cambridge's Department of Plant Sciences, and joint senior author of the paper.
Mycorrhiza fungi are attracting growing interest in agriculture. This new technique provides the ability to 'track and trace' the presence of symbiotic fungi in soils from different sources and locations. The researchers say this will enable the selection of fungi that colonise plants fastest and provide the biggest benefits in agricultural scenarios.
Understanding and exploiting the dynamics of plant root system colonisation by fungi has potential to enhance future crop production in an environmentally sustainable way. If plants can take up more nutrients naturally, this will reduce the need for artificial fertilisers - saving money and reducing associated water pollution.
CAPTION
Betalain coloured roots
CREDIT
Temur Yunusov and Alfonso Timoneda
CAPTION
Betalain coloured roots
CREDIT
Temur Yunusov and Alfonso Timoneda
New tracking system monitors danger to rainforests
Scientists develop novel new indicator for monitoring danger to the world's rainforests, which are losing capacity to cycle carbon and water
Rainforests are a powerful, natural solution to combat climate change -- providing water filtration, capturing carbon and regulating global temperatures. But major threats like large-scale land use changes, including agricultural expansion and clearcutting, have turned these biodiversity havens into one of the most endangered habitats on our planet.
In 2019, select scientists, including the University of Delaware's Rodrigo Vargas, met at the National Geographic headquarters in Washington, D.C., to discuss the threats to rainforests. The researchers pinpointed a need to develop a worldwide tracking system, which would find trends to help fight land degradation and promote conservation.
In the paper published on Friday, July 22 in the scientific journal One Earth, these researchers introduce the unique tropical rainforest index (TFVI), a baseline for rainforests across the entire globe. The scientist's goal is to detect and evaluate the vulnerability of rainforests to increasing threats. National Geographic and the Rolex Perpetual Planet Initiative funded the endeavor.
TFVI provides a snapshot of long-term observations, which began in 1982.
"Through this new index, we now have not only global coverage, but uniformity. We can summarize critical information about the health of rainforests," said Vargas, professor of ecosystem ecology and environmental change. "It gives us a benchmark and provides information about looming, future changes."
Using advanced satellite measurements, the research team systematically analyzed the climate and vegetation of each tropical region on Earth. The study's findings suggest that rainforests are losing their capacity to cycle carbon and water.
"We are losing major hotspots for biodiversity and carbon pools," Vargas said. "These are not small patches of land across the world; these are large sections of the Earth's surface."
The study's findings also indicate different regions of tropics have different responses to climate threats. Some regions, like Africa's Congo basin, are more resilient than other parts of the world. The Amazon Basin shows large-scale vulnerability to drying conditions of atmosphere, frequent droughts and large-scale land-use changes. In Southeast Asia, rainforests are stressed more from land use and species fragmentation than they are from climate, except for areas of peatlands that are, during El Nino years, now more vulnerable to fire.
"There is no single solution, no silver bullet that will work in every tropical rainforest. This highlights the needs for localized solutions," Vargas said. "But a general, global index also illuminates the need to design unified strategies to maximize the natural solutions that rainforests provide."
The unique tropical rainforest index methodically illustrates that the susceptibility of rainforests is actually much greater than previous predictions. Disturbed and fragmented areas have lost resilience to climate warming and droughts. Perhaps even more distressing were study findings suggesting that rainforests are losing their capacity to cycle carbon and water.
Tropical forests provide critical environmental services and benefits to society. These rainforests are changing from their historically, highly-diverse status to heavily transformed areas and managed land -- one that lacks the ability to, for example, sequester carbon from the atmosphere and support biodiversity.
"In addition to our moral responsibility to preserve our planet's biodiversity, because human's actions are influencing the global climate, we must be prepared to manage the consequences of these changes," Vargas said.
###
Studies examine different understandings, varieties of diversity
Investigates connection between political ideology, attitudes, and beliefs toward diversity
Attitudes toward diversity vary, and its meaning can often be difficult to find consensus about in an increasingly diverse but politically polarized nation such as the United States.
In a report published by Personality and Social Psychology Bulletin, University of Illinois Chicago researchers detail findings from three studies that explore the connection between political ideology, attitudes, and beliefs toward diversity.
"Our studies explored the possibility that attitudes toward 'diversity' are multidimensional rather than unidimensional and that ideological differences in diversity attitudes vary as a function of diversity subtype," said the report's lead author Kathryn Howard, UIC doctoral candidate in psychology.
The first study investigated ideological differences in attitudes towards a wide variety of diversity features. Participants rated how much diversity or homogeneity they would desire in 23 different community features that could be considered relevant to diversity.
The study found more conservative participants preferred viewpoint diversity and more liberal participants preferred demographic diversity.
The second study assessed participants' attitudes towards the general concept of diversity without providing a definition of the term. By investigating whether general attitudes towards diversity actually predict how people feel about specific types of diversity, the findings suggest that demographic features may be central to peoples' prototypes of diversity and that positive attitudes towards the general concept of diversity predicted demographic diversity preferences for both conservatives and liberals.
According to the researchers, "liberals were more likely than conservatives to endorse the general concept of diversity. Further, general diversity did not predict viewpoint diversity, but did significantly predict demographic diversity preferences. Thus, it may be that when people think of diversity in the abstract, people primarily imagine differences in ethnic and cultural groups, and do not necessarily consider diversity in attitudes."
Because the first two studies found that diversity is multidimensional and contains at least two distinct factors -- viewpoint and demographic diversity -- the third study aimed to investigate possible variations in the perceived meaning of "diversity" by asking participants to judge the relevance of a set of features to diversity.
Respondents were asked to imagine "a very diverse community," and to think about "the types of people and places that exist in a very diverse community." They also had to determine how relevant 29 different community features were to their image of a diverse community.
"People do not perceive diversity as a unidimensional or even bi-dimensional construct, but rather likely perceive at least three categories of diversity. Further, people rated demographic features as most relevant to diversity, followed by viewpoint and consumer features. Lastly, conservatives rated viewpoint features as more relevant to diversity than liberals, and liberals rated demographic features as more relevant to diversity than conservatives," the report states.
"Conservatives and liberals do not differ only in their attitudes toward diversity, but they also differ in their understanding of what 'diversity' means. When asked to think about 'diversity,' liberals and conservatives think about different things; different aspects of social life come to mind," Howard said.
The divergent political and social media realms where liberals and conservatives are centered, combined with increased political and affective polarization, likely accounts for the difference of perspective on both sides, according to the researchers, who add that the results provide hope for bridging the liberal-conservative political divide.
"Once you recognize that existence of multiple components of 'diversity,' it opens the door to identifying some aspects of diversity on which liberals and conservatives agree," said Daniel Cervone, UIC professor of psychology and study co-author. "Breaking the concept of 'diversity' into parts and identifying those parts on which people agree could be one small step toward reducing political polarization."
###
Matt Motyl of Facebook is a co-author on the report.
Neuroscientists posit that brain region is a key locus of learning
IMAGE: THE LOCUS COERULEUS IS DEEP IN THE BRAIN BUT PROJECTS CIRCUITS THROUGHOUT THE ORGAN. view more
CREDIT: SUR LAB/ MIT PICOWER INSTITUTE
Small and seemingly specialized, the brain's locus coeruleus (LC) region has been stereotyped for its outsized export of the arousal-stimulating neuromodulator norepinephrine. In a new paper and with a new grant from the National Institutes of Health, an MIT neuroscience lab is making the case that the LC is not just an alarm button but has a more nuanced and multifaceted impact on learning, behavior and mental health than it has been given credit for.
With inputs from more than 100 other brain regions and sophisticated control of where and when it sends out norepinephrine (NE), the LC's tiny population of surprisingly diverse cells may represent an important regulator of learning from reward and punishment, and then applying that experience to optimize behavior, said Mriganka Sur, Newton Professor of Neuroscience in The Picower Institute for Learning and Memory and the Department of Brain and Cognitive Sciences at MIT.
"What was formerly considered a homogenous nucleus exerting global, uniform influence over its many diverse target regions, is now suggested to be a heterogeneous population of NE-releasing cells, potentially exhibiting both spatial and temporal modularity that govern its functions," wrote Sur, postdoc Vincent Breton-Provencher and graduate student Gabrielle Drummond in a review article published last month in Frontiers in Neural Circuits.
The article presents copious emerging evidence from Sur's group and many others, suggesting that that the LC may integrate sensory inputs and internal cognitive states from across the brain to precisely exert its NE-mediated influence to affect actions - by throttling NE to the motor cortex - and the processing of resulting feedback of reward or punishment - by throttling NE to the prefrontal cortex.
To investigate that hypothesis, the team has begun working with a $2.1 million, 5-year NIH grant awarded in April. In this study they are engaging mice in learning tasks where they are cued by tones of varying pitches and volumes. Over the course of training the mice will learn that when a tone is high pitched, pressing a lever will yield a reward and when the tone is low pitched, the correct response would be to not push lest it experience an unpleasant air puff. By varying the tone volume, the experimenters will vary the certainty the mice can feel that they heard the cue correctly.
The hypothesis (borne out by preliminary data) predicts that the NE will matter in multiple crucial ways, Sur said. When the mouse hears the cue tone, if the pitch is low the LC would send less NE via a cadre of neurons to the motor cortex, reflecting the animal's belief that the lever should not be pushed because no reward will be forthcoming. Meanwhile the lower the volume, the less certainty the animal has in its decision. Conversely, a high tone of high volume would send more NE, reflecting the animal's certainty that pushing the lever would produce a reward.
After the mouse has acted, the more surprising the feedback, the more NE it will produce and send via a distinct group to the prefrontal cortex, stimulating greater learning. So for instance, if the mouse hears a faint, high tone and gingerly presses the lever, the surprise of a resulting reward will stimulate a strong output of NE to instruct the prefrontal cortex because its expectations weren't very high. Whenever a mouse guesses wrong and feels an air puff, that will stimulate the strongest NE release to the prefrontal cortex. After such dynamics, Sur's team has observed consistent performance changes on the subsequent trial.
"This is a way by which norepinephrine can be thought of as an arousal signal, but it's also, importantly, in the context of ongoing function a learning signal," Sur said. "It is both an execution signal and a learning signal, for both of which we can describe the actual quantitative relationships."
Not only will the team be measuring the activity of LC-NE neurons, they'll also take them over using optogenetics (in which neurons can be controlled with light), so that they can silence or amplify LC-NE output to show how doing each affects action and learning.
Understanding the true nature of how the LC works could be useful for improving treatments for certain disorders, Sur said. A potential treatment for PTSD, for instance, involves damping receptiveness to NE, but that also promotes drowsiness. A more principled and precise treatment could improve efficacy and reduce those side effects, he said.
"The hope is to affect the anxiety but not make you sleepy, if we understand the targets and theory behind it," Sur said. "That is the hope of basic science for treating disorders--to make things more and more specific, to define the circuits and the specificity of functions that a system is involved in."
Moreover the LC is an early region affected in Alzheimer's disease, he said. Addressing that loss in the right way could help sustain forms of learning and cognition.
