Category: Science News

{Your brain’s reward pathways become active during art-making activities like doodling, according to a new Drexel University study.}

Girija Kaimal, EdD, assistant professor in the College of Nursing and Health Professions, led a team that used fNIRS (functional near-infrared spectroscopy) technology to measure blood flow in the areas of the brain related to rewards while study participants completed a variety of art-making projects.

“This shows that there might be inherent pleasure in doing art activities independent of the end results. Sometimes, we tend to be very critical of what we do because we have internalized, societal judgements of what is good or bad art and, therefore, who is skilled and who is not,” said Kaimal of the study that was published The Arts in Psychotherapy. “We might be reducing or neglecting a simple potential source of rewards perceived by the brain. And this biologocial proof could potentially challenge some of our assumptions about ourselves.”

For the study, co-authored by Drexel faculty including Jennifer Nasser, PhD, and Hasan Ayaz, PhD, 26 participants wore fNIRS headbands while they completed three different art activities (each with rest periods between). For three minutes each, the participants colored in a mandala, doodled within or around a circle marked on a paper, and had a free-drawing session.

During all three activities, there was a measured increase in bloodflow in the brain’s prefrontal cortex, compared to rest periods where bloodflow decreased to normal rates.

The prefrontal cortex is related to regulating our thoughts, feelings and actions. It is also related to emotional and motivational systems and part of the wiring for our brain’s reward circuit. So seeing increased bloodflow in these areas likely means a person is experiencing feels related to being rewarded.

There were some distinctions between the activities in the data collected.

Doodling in or around the circle had the highest average measured bloodflow increase in the reward pathway compared to free-drawing (the next highest) and coloring. However, the difference between each form of art-making was not statistically significant, according to analysis.

“There were some emergent differences but we did not have a large-enough sample in this initial study to draw any definitive conclusions,” Kaimal said.

It was noted and tracked which participants in the study considered themselves artists so that their results could be compared to non-artists. In that way, Kaimal and her team hoped to understand whether past experience played a factor in triggering feelings of reward.

Doodling seemed to initiate the most brain activity in artists, but free-drawing was observed to be about the same for artists and non-artists. Interestingly, the set coloring activity actually resulted in negative brain activity in artists.

“I think artists might have felt very constrained by the pre-drawn shapes and the limited choice of media,” Kaimal explained. “They might also have felt some frustration that they could not complete the image in the short time.”

Again, however, these results regarding artists versus non-artists proved statistically insignificant, which might actually track with Kaimal’s previous research that found experience-level did not have a bearing on the stress-reduction benefits people had while making art.

Overall, though, the finding that any form of art-making resulted in the significant activation of feelings of reward are compelling, especially for art therapists who see art as a valuable tool for mental health.

In fact, in surveys administered to the participants after the activities were complete, respondents indicated that they felt more like they had “good ideas” and could “solve problems” than before the activities. Participants even said they felt the three-minute time spans for art-making weren’t long enough.

“There are several implications of this study’s findings,” Kaimal said. “They indicate an inherent potential for evoking positive emotions through art-making — and doodling especially. Doodling is something we all have experience with and might re-imagine as a democratizing, skill independent, judgment-free pleasurable activity.”

Additionally, Kaimal felt that the findings of increased self-opinion were intriguing.

“There might be inherent aspects to visual self-expression that evoke both pleasure and a sense of creative agency in ourselves,” she said.

Source:Science Daily

{Not only dogs but also wolves react to inequity — similar to humans or primates. This has been confirmed in a new study by comparative psychologists of the Messerli Research Institute of the University of Veterinary Medicine, Vienna. Wolves and dogs refused to cooperate in an experiment when only the partner got a treat or they themselves received a lower quality reward. Since this behaviour is equally strong in wolves and dogs, this sensitivity to inequity is not likely to be an effect of domestication, as has been assumed so far. It is rather a behaviour inherited from a common ancestor. The results were published in Current Biology.}

Recognising inequity is an important social skill in humans. This is particularly important when we cooperate with others. Different species of primates show this sensitivity to inequity, too. It has hardly been investigated if other species also realise inequity and react to it. Several studies with dogs were at least indicative of some form of inequity aversion, for example when the dogs themselves did not get food, but their partners did for the same action. So far, this skill in dogs has been attributed to their adaption to humans — domestication.

Their closest relatives, wolves, however, exhibit the same inequity aversion. This has been confirmed in a new study by the Messerli Research Institute and the Wolf Science Center of the University of Veterinary Medicine, Vienna. When the animals pressed a buzzer after the trainer had asked them to do so, and received nothing or a lower quality reward compared to their partners for the same action, they refused to participate in the experiment earlier. The behaviour was similar in equally raised wolves and dogs that had, therefore, the same life experience. This indicates a skill inherited from a common ancestor. Thus, domestication is not the only reason why dogs react to inequity.

No or lower quality rewards: wolves and dogs realise inequity

Jennifer Essler, Friederike Range and Sarah Marshall-Pescini investigated the behaviour of both canine species in a no-reward test and a quality test in which two animals were brought to two adjacent enclosures. When asked to do so, they had to alternately press a button with their paws in order to get a reward.

“In the no-reward test, only the partner got a treat in every trial. The test animal got nothing. In the quality test, both animals got a reward, but the preferred and thus higher quality treat was again given to the partner,” explained Jennifer Essler. “The ability to realise this inequity became evident when they refused to continue the experiment.” But interestingly, the animals continued easily when there was no partner. “This showed that the fact that they themselves had not received a reward was not the only reason why they stopped to cooperate with the trainer,” said Range. “They refuse to cooperate because the other one got something, but they themselves did not.”

Also in the quality test, wolves and dogs refused to continue to cooperate with the trainer and press the buzzer. “This reaction has not been shown in experiments so far. But it confirms even more clearly that wolves and dogs really understand inequity,” said Essler. Wolves, however, were considerably more sensitive than dogs, requiring more commands from the trainer to continue working.

Hierarchy is also important, but domestication seems to reduce the sense of inequity

The dogs’ and wolves’ rank within the pack was an additional factor for the point where the animals stopped to cooperate. “High-ranking animals become frustrated more quickly by inequity because they are not used to this situation: not receiving something at all or only of lower quality,” explained Range. “Thus, the hierarchy in their pack is directly linked to their reaction to inequity.”

After the experiments, the researchers also evaluated if the animals interacted with their test partners or the experimenter in a neutral enclosure. Wolves that had experienced inequity kept aloof from humans. Dogs did not. “Even if these animals do not directly live with humans, they are more amenable to us. At this point, domestication seems to influence the dogs’ behaviour. Their close contact to humans as pets could, thus, rather reduce their behaviour in such situations than trigger it.”

Source:Science Daily

{Two teams of astronomers have harnessed the power of the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to detect the prebiotic complex organic molecule methyl isocyanate [1] in the multiple star system IRAS 16293-2422. One team was co-led by Rafael Martín-Doménech at the Centro de Astrobiología in Madrid, Spain, and Víctor M. Rivilla, at the Osservatorio Astrofisico di Arcetri in Florence, Italy; and the other by Niels Ligterink at the Leiden Observatory in the Netherlands and Audrey Coutens at University College London, United Kingdom.}

“This star system seems to keep on giving! Following the discovery of sugars, we’ve now found methyl isocyanate. This family of organic molecules is involved in the synthesis of peptides and amino acids, which, in the form of proteins, are the biological basis for life as we know it,” explain Niels Ligterink and Audrey Coutens [2].

ALMA’s capabilities allowed both teams to observe the molecule at several different and characteristic wavelengths across the radio spectrum [3]. They found the unique chemical fingerprints located in the warm, dense inner regions of the cocoon of dust and gas surrounding young stars in their earliest stages of evolution. Each team identified and isolated the signatures of the complex organic molecule methyl isocyanate [4]. They then followed this up with computer chemical modelling and laboratory experiments to refine our understanding of the molecule’s origin [5].

IRAS 16293-2422 is a multiple system of very young stars, around 400 light-years away in a large star-forming region called Rho Ophiuchi in the constellation of Ophiuchus (The Serpent Bearer). The new results from ALMA show that methyl isocyanate gas surrounds each of these young stars.

Earth and the other planets in our Solar System formed from the material left over after the formation of the Sun. Studying solar-type protostars can therefore open a window to the past for astronomers and allow them to observe conditions similar to those that led to the formation of our Solar System over 4.5 billion years ago.

Rafael Martín-Doménech and Víctor M. Rivilla, lead authors of one of the papers, comment: “We are particularly excited about the result because these protostars are very similar to the Sun at the beginning of its lifetime, with the sort of conditions that are well suited for Earth-sized planets to form. By finding prebiotic molecules in this study, we may now have another piece of the puzzle in understanding how life came about on our planet.”

Niels Ligterink is delighted with the supporting laboratory results: “Besides detecting molecules we also want to understand how they are formed. Our laboratory experiments show that methyl isocyanate can indeed be produced on icy particles under very cold conditions that are similar to those in interstellar space This implies that this molecule — and thus the basis for peptide bonds — is indeed likely to be present near most new young solar-type stars.”

{{Notes}}

[1] A complex organic molecule is defined in astrochemistry as consisting of six or more atoms, where at least one of the atoms is carbon. Methyl isocyanate contains carbon, hydrogen, nitrogen and oxygen atoms in the chemical configuration CH3NCO. This very toxic substance was the main cause of death following the tragic Bhopal industrial accident in 1984.

[2] The system was previously studied by ALMA in 2012 and found to contain molecules of the simple sugar glycolaldehyde, another ingredient for life.

[3] The team led by Rafael Martín-Doménech used new and archive data of the protostar taken across a large range of wavelengths across ALMA’s receiver Bands 3, 4 and 6. Niels Ligterink and his colleagues used data from the ALMA Protostellar Interferometric Line Survey (PILS), which aims to chart the chemical complexity of IRAS 16293-2422 by imaging the full wavelength range covered by ALMA’s Band 7 on very small scales, equivalent to the size of our Solar System.

[4] The teams carried out spectrographic analysis of the protostar’s light to determine the chemical constituents. The amount of methyl isocyanate they detected — the abundance — with respect to molecular hydrogen and other tracers is comparable to previous detections around two high-mass protostars (i.e. within the massive hot molecular cores of Orion KL and Sagittarius B2.

[5] Martín-Doménech’s team chemically modelled gas-grain formation of methyl isocyanate. The observed amount of the molecule could be explained by chemistry on the surface of dust grains in space, followed by chemical reactions in the gas phase. Moreover, Ligterink’s team demonstrated that the molecule can be formed at extremely cold interstellar temperatures, down to 15 Kelvin (-258 degrees Celsius), using cryogenic ultra-high-vacuum experiments in their laboratory in Leiden.

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This research was presented in two papers: “First Detection of Methyl Isocyanate (CH3NCO) in a solar-type Protostar” by R. Martín-Doménech et al. and “The ALMA-PILS survey: Detection of CH3NCO toward the low-mass protostar IRAS 16293-2422 and laboratory constraints on its formation,” by N. F. W. Ligterink et al.. Both papers will appear in the same issue of the Monthly Notices of the Royal Astronomical Society.

One team is composed of: R. Martín-Doménech (Centro de Astrobiología, Spain), V. M. Rivilla (INAF/Osservatorio Astrofisico di Arcetri, Italy), I. Jiménez-Serra (Queen Mary University of London, UK), D. Quénard (Queen Mary University of London, UK), L. Testi (INAF/Osservatorio Astrofisico di Arcetri, Italy; ESO, Garching, Germany; Excellence Cluster “Universe,” Germany) and J. Martín-Pintado (Centro de Astrobiología, Spain).

The other team is composed of: N. F. W. Ligterink (Sackler Laboratory for Astrophysics, Leiden Observatory, the Netherlands), A. Coutens (University College London, UK), V. Kofman (Sackler Laboratory for Astrophysics, The Netherlands), H. S. P. Müller (Universität zu Köln, Germany), R. T. Garrod (University of Virginia, USA), H. Calcutt (Niels Bohr Institute & Natural History Museum, Denmark), S. F. Wampfler (Center for Space and Habitability, Switzerland), J. K. Jørgensen (Niels Bohr Institute & Natural History Museum, Denmark), H. Linnartz (Sackler Laboratory for Astrophysics, The Netherlands) and E. F. van Dishoeck (Leiden Observatory, The Netherlands; Max-Planck-Institut für Extraterrestrische Physik, Germany).\

Source:Science Daily

{Roughly 115 million years ago, when the ancient supercontinent Gondwana was breaking apart, a mushroom fell into a river and began an improbable journey. Its ultimate fate as a mineralized fossil preserved in limestone in northeast Brazil makes it a scientific wonder, scientists report in the journal PLOS ONE.}

The mushroom somehow made its way into a highly saline lagoon, sank through the stratified layers of salty water and was covered in layer upon layer of fine sediments. In time — lots of it — the mushroom was mineralized, its tissues replaced by pyrite (fool’s gold), which later transformed into the mineral goethite, the researchers report.

“Most mushrooms grow and are gone within a few days,” said Illinois Natural History Survey paleontologist Sam Heads, who discovered the mushroom when digitizing a collection of fossils from the Crato Formation of Brazil. “The fact that this mushroom was preserved at all is just astonishing.

“When you think about it, the chances of this thing being here — the hurdles it had to overcome to get from where it was growing into the lagoon, be mineralized and preserved for 115 million years — have to be minuscule,” he said.

Before this discovery, the oldest fossil mushrooms found had been preserved in amber, said INHS mycologist Andrew Miller, a co-author of the new report. The next oldest mushroom fossils, found in amber in Southeast Asia, date to about 99 million years ago, he said.

“They were enveloped by a sticky tree resin and preserved as the resin fossilized, forming amber,” Heads said. “This is a much more likely scenario for the preservation of a mushroom, since resin falling from a tree directly onto the forest floor could readily preserve specimens. This certainly seems to have been the case, given the mushroom fossil record to date.”

The mushroom was about 5 centimeters (2 inches) tall. Electron microscopy revealed that it had gills under its cap, rather than pores or teeth, structures that release spores and that can aid in identifying species.

“Fungi evolved before land plants and are responsible for the transition of plants from an aquatic to a terrestrial environment,” Miller said. “Associations formed between the fungal hyphae and plant roots. The fungi shuttled water and nutrients to the plants, which enabled land plants to adapt to a dry, nutrient-poor soil, and the plants fed sugars to the fungi through photosynthesis. This association still exists today.”

The researchers place the mushroom in the Agaricales order and have named it Gondwanagaricites magnificus.

Source:Science Daily

{Fear of death is a fundamental part of the human experience — we dread the possibility of pain and suffering and we worry that we’ll face the end alone. Although thinking about dying can cause considerable angst, new research suggests that the actual emotional experiences of the dying are both more positive and less negative than people expect.}

The findings are published in Psychological Science, a journal of the Association for Psychological Science.

“When we imagine our emotions as we approach death, we think mostly of sadness and terror,” says psychological scientist Kurt Gray of the University of North Carolina at Chapel Hill. “But it turns out, dying is less sad and terrifying — and happier — than you think.”

The research, which examined the writings of terminally ill patients and inmates on death row, suggests that we focus disproportionately on the negative emotions caused by dying, without considering the broader context of everyday life.

“Humans are incredibly adaptive — both physically and emotionally — and we go about our daily lives whether we’re dying or not,” Gray explains. “In our imagination, dying is lonely and meaningless, but the final blog posts of terminally ill patients and the last words of death row inmates are filled with love, social connection, and meaning.”

The positive emotions that come with this kind of meaning-making were exquisitely displayed in a recent Modern Love column, written by beloved children’s author Amy Krouse Rosenthal. Rosenthal, who died of ovarian cancer 10 days after her column was published in The New York Times, wrote with profound love and humor about finding someone to marry her husband after she died.

“The column was so touching because it was so positive, so filled with love and hope,” says Gray. “While such positivity seems strange in someone so near death, our work shows that it is actually fairly typical.”

Gray, his graduate student Amelia Goranson, and their co-authors Ryan Ritter, Adam Waytz, and Michael Norton started thinking about the emotional experience of dying when they came across the last words of death-row inmates in Texas, collected by the state’s Department of Justice. They were surprised by how upbeat the statements were, and wondered whether our feelings about death and dying might be clouded by our tendency to zero in on negative experiences.

In their first study, Gray and colleagues analyzed the emotional content of blog posts from terminally ill patients who were dying of either cancer or amyotrophic lateral sclerosis (ALS). To be included in the study, the blogs had to have at least 10 posts over at least 3 months and the author had to have died in the course of writing the blog. For comparison, the researchers asked a group of online participants to imagine that they had been diagnosed with terminal cancer and to write a blog post, keeping in mind that they only a few months to live.

Using a computer-based algorithm, trained research assistant coders, and online participant coders, the researchers analyzed the actual and imagined blog posts for words that described negative and positive emotions, such as “fear,” “terror,” “anxiety,” “happiness,” and “love.”

The results revealed that blog posts from individuals who were terminally ill included considerably more positive emotion words and fewer negative emotion words than did those written by participants who simply imagined they were dying.

Looking at the patients’ blog posts over time, the researchers also found that their use of positive emotion words actually increased as they neared death, while their use of negative emotion words did not. These patterns held even after Gray and colleagues took the overall word count and number of blog posts into account, suggesting that the increase in positive emotion words was not simply due to the effects of writing over time.

In a second study, the researchers conducted similar analyses comparing the last words of inmates on death row with the poetry of death-row inmates and the imagined last words of another group of online participants.

Again, they found that the words of those who were actually close to death were less negative and more positive in emotional tone than the words of those who were not close to death.

Both the terminally ill patients and the inmates facing execution seemed to focus on things that help us make meaning of life, including religion and family, suggesting that such things may help to quell anxiety about death as it approaches.

Gray and his co-authors acknowledge that the findings may not apply to all people who are approaching death — it’s unclear whether individuals facing a great deal of uncertainty or those who die of old age express similarly positive emotions near the end of life.

Ultimately, the findings suggest that our expectations may not match the reality of dying, which has important implications for how we treat people who are dying.

“Currently, the medical system is geared toward avoiding death — an avoidance that is often motivated by views of death as terrible and tragic,” the researchers write in their paper. “This focus is understandable given cultural narratives of death’s negativity, but our results suggest that death is more positive than people expect: Meeting the grim reaper may not be as grim as it seems.”

Source:Science Daily

{A computer’s ability to predict a patient’s lifespan simply by looking at images of their organs is a step closer to becoming a reality, thanks to new research led by the University of Adelaide.}

The research, now published in the Nature journal Scientific Reports, has implications for the early diagnosis of serious illness, and medical intervention.

Researchers from the University’s School of Public Health and School of Computer Science, along with Australian and international collaborators, used artificial intelligence to analyse the medical imaging of 48 patients’ chests. This computer-based analysis was able to predict which patients would die within five years, with 69% accuracy — comparable to ‘manual’ predictions by clinicians.

This is the first study of its kind using medical images and artificial intelligence.

“Predicting the future of a patient is useful because it may enable doctors to tailor treatments to the individual,” says lead author Dr Luke Oakden-Rayner, a radiologist and PhD student with the University of Adelaide’s School of Public Health.

“The accurate assessment of biological age and the prediction of a patient’s longevity has so far been limited by doctors’ inability to look inside the body and measure the health of each organ.

“Our research has investigated the use of ‘deep learning’, a technique where computer systems can learn how to understand and analyse images.

“Although for this study only a small sample of patients was used, our research suggests that the computer has learnt to recognise the complex imaging appearances of diseases, something that requires extensive training for human experts,” Dr Oakden-Rayner says.

While the researchers could not identify exactly what the computer system was seeing in the images to make its predictions, the most confident predictions were made for patients with severe chronic diseases such as emphysema and congestive heart failure.

“Instead of focusing on diagnosing diseases, the automated systems can predict medical outcomes in a way that doctors are not trained to do, by incorporating large volumes of data and detecting subtle patterns,” Dr Oakden-Rayner says.

“Our research opens new avenues for the application of artificial intelligence technology in medical image analysis, and could offer new hope for the early detection of serious illness, requiring specific medical interventions.”

The researchers hope to apply the same techniques to predict other important medical conditions, such as the onset of heart attacks.

The next stage of their research involves analysing tens of thousands of patient images.

Source:Science Daily

{Scientists at Georgia State University have rewired the neural circuit of one species and given it the connections of another species to test a hypothesis about the evolution of neural circuits and behavior.}

Neurons are connected to each other to form networks that underlie behaviors. Drs. Akira Sakurai and Paul Katz of Georgia State’s Neuroscience Institute study the brains of sea slugs, more specifically nudibranchs, which have large neurons that form simple circuits and produce simple behaviors. In this study, they examined how the brains of these sea creatures produce swimming behaviors. They found that even though the brains of two species — the giant nudibranch and the hooded nudibranch — had the same neurons, and even though the behaviors were the same, the wiring was different.

The researchers blocked some of the connections in the giant nudibranch using curare, a paralyzing poison used on blow darts by indigenous South Americans. This prevented the brain of the giant nudibranch from producing the pattern of impulses that would normally cause the animal to swim. Then, they inserted electrodes into the neurons to create artificial connections between the brain cells that were based on connections from the hooded nudibranch. The brain was able to produce rhythmic, alternating activity that would underlie the swimming behavior, showing these two species produce their swimming behavior using very different brain mechanisms.

The findings are published in the journal Current Biology.

“Behaviors that are homologous and similar in form would naturally be assumed to be produced by similar neural mechanisms,” said Katz, co-author of the study and a Regent’s Professor in the Neuroscience Institute at Georgia State. “This and previous studies show that connectivity of the neural circuits of two different species of sea slugs differ substantially from each other despite the presence of homologous neurons and behaviors. Thus, the evolution of microcircuitry could play a role in the evolution of behavior.”

The study’s results are significant for several reasons. First, they show that over the course of evolution, behaviors might be conserved, but the underlying neural basis for the behaviors could shift.

In addition, other work by these researchers and Katz’s lab has underscored the conclusion that neurons are conserved, but differ in function across species. This has implications for extrapolating results across species in general and means caution must be taken in assuming that neural mechanisms are conserved even though brain regions and behaviors are present.

Sakurai is first author of the study and a research scientist in the Neuroscience Institute at Georgia State.

The research was funded by the National Science Foundation.

The researchers also recently published results from similar work in the Journal of Neurophysiology. They reported that neural connectivity between the same neurons in two different species of sea slugs varies independently of behavior and the evolutionary history of an organism.

Source:Science Daily

{New study reveals the importance of African groundwater in kick-starting the evolutionary history of humans}

An international team led by a researcher at Cardiff University believe that the movement of our ancestors across East Africa was shaped by the locations of groundwater springs.

In a new study, the team argue that the springs acted as pit stops to allow early humans to survive as they moved across the African landscape.

The team believe that populations were able to mix with each other at these junctions, influencing genetic diversity and, ultimately, the evolution of the human population.

The results of the study have been published in the journal Nature Communications.

Humans are thought to have first evolved in Africa, and evidence currently suggests that early humans first migrated out of the continent probably between 2 million and 1.8 million years ago.

During this time, rainfall was affected by the African monsoon which strengthened and weakened on a 23,000 year cycle driven by the precession of the equinoxes. During intense periods of aridity, monsoon rains would have been light and drinking water in short supply.

By mapping persistent springs across the African landscape, the researchers have been able to model how our ancestors may have moved between water sources at different times and how this impacted their ability to traverse the landscape as the climate changed.

Lead author of the study Dr Mark Cuthbert, from Cardiff University’s School of Earth and Ocean Sciences, said: “We found that the geology is really important in controlling how much rainfall gets stored in the ground during wet periods. Modelling the springs showed that many could still flow during long dry periods because this groundwater store acts like a buffer against climate change.

“As such, we begin to see that the geology, and not just the climate, control the availability of water — the landscape was a catalyst for change in Africa.”

Co-author of the study Professor Matthew Bennett, from Bournemouth University, said: “What we are seeing is the movement of people across vast areas of land. You can think of springs as the service stations or rest stops along the way, where people would be drawn to get their vital water sources.

“Through our mapping we have found the routes on the current landscape by which our ancestors may have walked, like motorways, taking people from one water source to the next. This is another vital clue in understanding how these people migrated across the African continent, from water source to source, and how this may have impacted on gene flow and mixing.”

Isabelle Durance, Director of the Cardiff University Water Research Institute, said: “Groundwater currently provides nearly a third of the world’s population with drinking water. It is also used to produce the largest share of the world’s food supply and is a vital component of our natural capital, but this research shows that it may have also shaped our evolutionary history.”

Source:Science Daily

{The origin of animals was one of the most important events in the history of Earth. Beautifully preserved fossil embryos suggest that our oldest ancestors might have existed a little more than half a billion years ago.}

Yet, fossils are rare, difficult to interpret, and new, older fossils are constantly discovered.

An alternative approach to date the ‘tree of life’ is the molecular clock, introduced in the early 1960s by twice Nobel Laureate Linus Pauling, which uses genetic information.

Early molecular clock studies assumed that mutation accumulated at a fixed rate across all species and concluded that our oldest ancestor might have existed around 1.5 billions of years ago, a date that is almost three-times as old as the oldest fossil evidence of animal life.

These results sparked heated, scientific debates that only eased off in the last decade when a new generation of more realistic “relaxed” clock methods, that do not assume constancy of the mutation rate, started to close the gap between molecules and fossils indicating that animals are unlikely to be older than around 850 million of years.

However, using a recently developed relaxed molecular clock method called RelTime, a team of scientists at Oakland (Michigan) and Temple (Philadelphia) dated the origin of animals at approximately 1.2 billion years ago reviving the debate on the age of the animals.

Puzzled by the results of the American team, researchers from the University of Bristol and Queen Mary University of London decided to take a closer look at RelTime and found that it failed to relax the clock. Their findings are published in the journal Genome Biology and Evolution.

Professor Philip Donoghue from the University of Bristol’s School of Earth Sciences, said: “What caught our attention was that results obtained using RelTime were in strong disagreement with a diversity of different studies, from different research groups and that used different software and data, all of which broadly agreed that animals are unlikely to be older than approximately 850 million years.”

Dr Mario dos Reis, a co-author from London, added: “Generally scientists use Bayesian methods to relax the clock. These methods use explicit probability models to account for the uncertainty in the fossil record and in the mutation rate.

“Bayesian methods borrow tools from financial mathematics to model variation in mutation rate in a way that is similar to that used to model the stochastic variation in stock prices with time.

“By applying these sophisticated mathematical tools, Bayesian methods relax the clock and estimate divergence times. However, RelTime is not a Bayesian method.”

Dr Jesus Lozano-Fernandez, also from the University of Bristol, added: “Estimating divergence times is difficult and different relaxed molecular clock methods use different approaches to do so. However, we discovered that the RelTime algorithm failed to relax the clock along the deepest branches of the animal tree of life.”

Bristol’s Professor Davide Pisani concluded: “Current Bayesian methods date the last common animal ancestor to less than approximately 850 millions of years ago, in relatively good agreement with the fossil record.

“RelTime suggested that animals are much older but it turned out that it suffers from the same problems of the early clock methods.

“This clearly indicates that older ideas suggesting that animals might be twice or three times as old as the oldest animal fossil are erroneous and only emerge when changes in mutation rate are incorrectly estimated.

“RelTime results sounded like a blast from the past, but their provably erroneous nature ended up blasting these same old ideas that they were trying to revive.”

Source:Science Daily

{For a long time, researchers thought of the visual cortex as a brain area that determines what you perceive based on information coming from the eyes. Neuroscientists from Radboud University now show that the area is also involved in the prediction of future events. Nature Communications publishes the results on May 23.}

Imagine that you are standing on the sidewalk, ready to cross the street. A car approaches and you need to decide whether to wait, or to cross the street before the car passes by. Did you ever wonder how you predict the future trajectory of the car? An experiment by Matthias Ekman and fellow researchers from Radboud University’s Donders Institute shows that the primary visual cortex, the main visual area of our brain, is not only involved in perceiving the car, but also in predicting its future locations.

{{White dots}}

The Radboud researchers designed an experiment that mimics this kind of situation. Instead of a car, study participants were shown a white dot moving quickly from the left to the right side of the screen, while lying in an fMRI scanner. The brain activity pattern in their visual cortex proved remarkably similar to the visual dot stimulus that was shown on the screen.

The crucial part of the experiment began after participants had watched the moving dot sequence for a few minutes. Now, occasionally, only the first dot on the left side of the screen was shown. Interestingly, the visual cortex’s activity pattern represented not only the starting point of the dot sequence — the one that was shown on screen — but also the remaining dots of the sequence. Ekman: “Our results show that we form expectations about upcoming events, and that the visual cortex can complete a sequence from only partial input.”

{{Automatic process}}

The predictive power of the visual cortex is also apparent from the results of one study condition in which participants were asked to focus on a changing letter in the background, completely ignoring the moving dots — see this video for an illustration of the task. Surprisingly, the same pattern of activity as before was measured in the visual cortex. “Your visual cortex predicts these events, even when your attention is elsewhere” according to Ekman. “The fact that the event prediction is independent from the attentional state, suggests that it reflects an automatic process.”

Of course, the MRI experiment is simplified compared to real life. But according to Ekman, the results can still tell us about how we anticipate future events in the ever changing world. “Our visual cortex might constantly predict events happening all around us on a daily basis: the rotating arms of a windmill, or how to catch the ball that is moving towards us.” In a follow-up study, the researchers examine which brain areas collaborate with the visual cortex to anticipate upcoming events. “We expect that the hippocampus — a brain area linked to memory — plays an important role in this process.”

Source:Science Daily