Knowledge Update

​New York, June 19 (IANS) People with Parkinson's disease have a form of impaired decision-making that may be a major contributor to the movement problems that characterise the disease, a team of researchers has found.

Undertaken by researchers from the University of California - Los Angeles, the study suggested that the neurological factors underlying Parkinson's may be more complex than commonly believed. 

The study, publishing in the journal Current Biology also, could pave the way for strategies to detect Parkinson's earlier in its course.

The led team found that as compared to healthy individuals, people with early-stage Parkinson's have difficulty with perceptual decision-making only when the sensory information before them is weak enough that they must draw on prior experiences. 

When the sensory information is strong, individuals with Parkinson's are able to make decisions as well as people who are healthy.

"This tells us that the problem for people with Parkinson's disease is not walking per se, but rather in generating the walking pattern without the assistance of sensory information," said study senior author Michele Basso.

"The patients with Parkinson's disease in our study were impaired only when they had to rely on memory information to guide their actions. We believe this fundamental problem of decision-making in the absence of sufficient sensory information may be what is underlying some of the movement disorder symptoms," Basso added.

The disease has no cure, although medication or surgery can relieve symptoms to a certain extent.

"Parkinson's disease has long been seen as purely a motor problem, limited mostly to a section of the brain called the basal ganglia and a neurotransmitter called dopamine that is not produced at sufficient levels," Basso noted.​

New York, June 18 (IANS) Researchers led by an Indian-origin scientist have developed a software that can turn any smartphone into an eye-tracking device, a discovery that can help in psychological experiments and marketing research.

In addition to making existing applications of eye-tracking technology more accessible, the system could enable new computer interfaces or help detect signs of incipient neurological disease or mental illness.

Since few people have the external devices, there's no big incentive to develop applications for them. 

“Since there are no applications, there's no incentive for people to buy the devices. We thought we should break this circle and try to make an eye tracker that works on a single mobile device, using just your front-facing camera,” explained Aditya Khosla, graduate student in electrical engineering and computer science at Massachusetts Institute of Technology (MIT).

Khosla and his colleagues from MIT and University of Georgia built their eye tracker using machine learning, a technique in which computers learn to perform tasks by looking for patterns in large sets of training examples.

Currently, Khosla says, their training set includes examples of gaze patterns from 1,500 mobile-device users. 

Previously, the largest data sets used to train experimental eye-tracking systems had topped out at about 50 users.

To assemble data sets, "most other groups tend to call people into the lab," Khosla says. 

"It's really hard to scale that up. Calling 50 people in itself is already a fairly tedious process. But we realised we could do this through crowdsourcing,” he added.

In the paper, the researchers report an initial round of experiments, using training data drawn from 800 mobile-device users. 

On that basis, they were able to get the system's margin of error down to 1.5 centimetres, a twofold improvement over previous experimental systems.

The researchers recruited application users through Amazon's Mechanical Turk crowdsourcing site and paid them a small fee for each successfully executed tap. The data set contains, on average, 1,600 images for each user.

The team from MIT's Computer Science and Artificial Intelligence Laboratory and the University of Georgia described their new system in a paper set to presented at the "Computer Vision and Pattern Recognition" conference in Las Vegas on June 28.

​New York, June 16 (IANS) Scientists have discovered an ancient space rock in a Swedish quarry which is a type of meteorite never before found on the Earth and can shed more light on the evolution of life.

The new meteorite, called Ost 65, appears to be from the missing partner in a massive asteroid collision 470 million years ago. 

The collision sent debris falling to the Earth over about a million years and may have influenced a great diversification of life in the Ordovician Period which lasted almost 45 million years, beginning 488.3 million years ago and ending 443.7 million years ago. 

One of the objects involved in this collision is well-known. It was the source of L-chondrites, the most common type of meteorite. But the identity of the object that hit it has been a mystery.

"In our entire civilisation, we have collected over 50,000 meteorites and no one has seen anything like this one before," said study co-author Qing-zhu Yin, professor of geochemistry and planetary sciences at University of California-Davis. 

"Discovering a new type of meteorite is very, very exciting,” he added in a paper reported in the journal Nature Communications.

Ost 65 was discovered in Sweden's Thorsberg quarry, source of more than 100 fossil meteorites. 

Measuring just under four-inches wide, it looks like a gray cow patty plopped into a pristine layer of fossil-rich pink limestone. 

By measuring how long Ost 65 was exposed to cosmic rays, the team established that it travelled in space for about a million years before it fell to the Earth 470 million years ago. 

This timeline matches up with L-chondrite meteorites found in the quarry.

According to the researchers, about 100 times as many meteorites slammed into the Earth during the Ordovician Period compared with today owing to the massive collision in the asteroid belt. 

This rain of meteorites may have opened new environmental niches for organisms, thus boosting both the diversity and complexity of life on Earth.

"I think this shows the interconnectedness of the entire solar system in space and time, that a random collision 470 million years ago in the asteroid belt, could dictate the evolutionary path of species here on Earth," Yin explained.​

​New York, June 16 (IANS) Obese people may find it difficult to stay away from sweet foods than individuals who are lean, because of a dysfunction in their brains, finds a new study.

Extra body fat can exert effects on how our brains perceive rewards when we eat sweets, the study said.

The findings showed that the reward system in obese people brains' operates in a different manner than in those who are lean.

As people move from adolescence to adulthood, they tend to be less fond of sweets as a result of a decrease in dopamine levels -- the main chemical in the brain that makes us feel good. 

The fall in dopamine levels makes the older adults less attracted to sweets.

Both younger age and fewer dopamine receptors were found to be associated with a higher preference for sweets in those of normal weight. 

"We found disparities in preference for sweets between individuals and also found individual variations in dopamine receptors," said Tamara Hershey, Professor at Washington University.

"Some people have high levels and some low. In people with normal weight having fewer dopamine receptors was associated with a higher preference for sweets," Hershey noted.

However, in people with obesity, that is not the case, the researchers said.

Dysfunctioning in the brain's reward system of obese individuals makes them more vulnerable to sweet cravings.

The relationship between their age, sweetness preferences and dopamine receptors also did not follow the pattern seen in people who weighed less.

Insulin resistance or some other metabolic change linked to obesity could contribute to the absence of these associations in the obese group, the researchers explained.

"We believe we may have identified a new abnormality in the relationship between reward response to food and dopamine in the brains of individuals with obesity," lead author M Yanina Pepino, Assistant Professor at Washington University, added.

For the study, published online in the journal Diabetes, the team analysed 20 healthy volunteers who were aged between 20-40 years and compared them with 24 people considered obese, each of whom had a body mass index of 30 or higher. 

The participants received drinks containing varying levels of sugar to determine the degrees of sweetness each individual preferred. 

Positron emission tomography (PET) scans was conducted to identify dopamine receptors linked to rewards in each person's brain. ​

New York, June 17 (IANS) Exercise, even a small amount, can help alleviate symptoms of attention-deficit/hyperactivity disorder (ADHD) in adults, say researchers.

ADHD symptoms can lead to depression, low energy and motivation, poor performance at work or school and also increased traffic accidents.

A single bout of exercise has psychological benefits for adults with these elevated ADHD symptoms, which lead to anxiety, the findings showed.

"Exercise is already known as a stress reducer and mood booster, so it really has the potential to help those suffering with ADHD symptoms," said the study's senior author Patrick O'Connor, professor at University of Georgia in the US. 

"And while prescription drugs can be used to treat these symptoms, there's an increased risk of abuse or dependence and negative side effects. Those risks don't exist with exercise," O'Connor said.

The study tested 32 young men with elevated ADHD symptoms who cycled at a moderate intensity for 20 minutes on one day, and on another day sat and rested for 20 minutes as a control condition. 

The participants were asked to perform a task requiring focus both before and after the different conditions, and researchers noted leg movement, mood, attention and self-reported motivation to perform the task.

As a result, researchers found that it was only after the exercise when the participants felt motivated to do the task. They also felt less confused and fatigued and instead felt more energetic. 

The study was published in the journal Medicine and Science in Sports and Exercise.

Interestingly, leg movements and performance on the task did not change after the exercise - rather, the exercise helped the young men feel better about doing the task.​

​New York, June 17 (IANS) Women who go to college intending to become engineers stay in the profession less often than men, as a result of gender disparities faced by them during their assignments, finds a new study.

Overall, about 20 per cent of under-graduate engineering degrees are awarded to women, but only 13 per cent of the engineering workforce is female, the study said.

The findings showed that women often feel marginalised, especially during internships, other summer work opportunities, or team-based educational activities.

"Gender makes a big difference. Informal interactions with peers and everyday sexism in teams and internships are particularly salient building blocks of [gender] segregation," said Susan Silbey, Professor at Massachusetts Institute of Technology.

Women are more likely than men to enter the field of engineering with the explicit notion that it will be a "socially responsible" profession that will "make a difference in people's lives."

But, gender dynamics seem to generate more opportunities for men to work on the most challenging problems, while women tend to be assigned routine tasks or simple managerial duties.

"For many women, their first encounter with collaboration is to be treated in gender stereotypical ways," the researchers rued.

“As a result of their experiences at these moments, women who have developed high expectations for their profession -- expecting to make a positive social impact as engineers -- can become disillusioned with their career prospects," Silbey added.

For the study, the team asked more than 40 undergraduate engineering students to keep twice-monthly diaries that generated more than 3,000 individual diary entries that the scholars systematically examined.

The diary entries frequently mentioned the everyday gender disparities these women faced.

Thus, such gender disparities leads women to question whether other professions could be a better vehicle for affecting positive change in the society -- their key motivator -- and thus prompt them to leave engineering, said the paper published in the journal Work and Occupations.​

​London, June 17 (IANS) Unable to retain your memory? A new study suggests that physical exercise four hours after learning can significantly improve long-term memory and memory traces.

The findings showed that students who exercised four hours after learning retained the information for two days in comparison to those who exercised either immediately or not at all. 

Exercise after the stipulated time was associated with more precise representations in the hippocampus -- a brain region important for learning and memory.

"It shows that we can improve memory consolidation and long term memory by doing sports after learning," said Guillen Fernandez from Radboud University in the Netherlands.

"The study suggests that appropriately timed physical exercise can improve long-term memory and highlights the potential of exercise as an intervention in educational and clinical settings," Fernandez noted.

The study, published in the journal Current Biology, involved 72 students, who were made to learn 90 picture-location associations for 40 minutes. 

After that, they were randomly assigned to one of three groups: first group performed the exercise immediately after learning. The second group performed the exercise four hours later and the third did not perform any exercise.

The exercise consisted of 35 minutes of interval training on an exercise bike at an intensity of up to 80 per cent of participants' maximum heart rates.

​London, June 17 (IANS) Being overweight during adolescence can put men at significantly higher risk of developing severe liver disease later in life, says a study.

The findings are based on 40 years follow-up of study of nearly 45,000 Swedish men.

The study showed that adolescent males with a body mass index (BMI) above 25 are at a 64 per cent increased risk of developing severe liver diseases and liver cell cancer in their late lives. 

Even for one kg/m2 increase in BMI, obese males can face a five per cent increased risk, the study said.

"It is possible that this increased risk is caused by a longer exposure to being overweight, compared to becoming overweight or obese later in life and that individuals with a longer history of being overweight have an increased risk of severe liver disease," said lead investigator Hannes Hagstrom from Karolinska University in Sweden.

In addition, overweight and obesity are associated with a worse prognosis in several liver diseases, such as non-alcoholic fatty liver disease (NAFLD), hepatitis B and C as well as alcoholic liver disease.

The increased risk of a high BMI for the development of severe liver disease later in life is already present from an early age, commented the researchers.

"The increased prevalence of overweight and obesity has also contributed to the worldwide rise in liver diseases," Hagstrom added.

It has been estimated that if current trends continue, there will be more than two billion overweight and over one billion obese individuals worldwide by 2030, said the paper published in the Journal of Hepatology. 

The researchers examined approximately 45,000 Swedish men, over a period of 40 years, to investigate if the body mass index (BMI) in adolescence developed severe liver diseases in later life. 

The results of the follow-up revealed 393 men diagnosed with severe liver diseases and being overweight was a risk factor for developing severe liver disease after adjusting for a variety of confounding factors, including alcohol and tobacco. ​

​New York, June 15 (IANS) Type 2 diabetes may lead to significant changes in the brain's grey matter volume in teenagers, says a study involving an Indian-origin researcher.

Grey matter is the brain region involved in muscle control and sensory perception such as seeing and hearing, memory, emotions, speech, decision-making and self-control.

"Previous studies suggested that youth with Type 2 diabetes have changes in brain structure and poorer cognitive function scores compared to their peers," said Amy Sanghavi Shah, Physician-Scientist at Cincinnati Children's Hospital Medical Centre in the US. 

The findings showed that adolescents with Type 2 diabetes have six regions with significantly less grey matter and three with significantly more. 

Also, a relationship was found between less grey matter volume in the brain and the ability to pronounce and sound out unfamiliar words.

"Preventing Type 2 diabetes in adolescents is important to prevent possible complications in the future," added lead author Jacob Redel from Cincinnati Children's Hospital.

"Our results do not show cause and effect. But studies in adults with Type 2 diabetes with longer duration of disease also show brain volume differences, brain vascular changes and cognitive decline," Redel noted, stressing that the team only found an association between the two.

For the study, the team analysed 20 teenagers with Type 2 diabetes and compared them to 20 teenagers without diabetes who were similar in age, race and sex. 

All participants in the study had high-resolution MRIs. Neither group had prior neurological nor psychological disease or prior abnormal MRIs.

The study was presented at the American Diabetes Association's Scientific Sessions in New Orleans in the US, recently.​

​New York, June 15 (IANS) While a conclusive answer to why women have a longer lifespan as compared to men still eludes scientists, a host of factors - from differences in hormones to immune system variations - could be at work, suggests new research.

In a perspective piece published in the journal Cell Metabolism, researchers from the University of Alabama at Birmingham explored what gives women the survival advantage.

"Humans are the only species in which one sex is known to have a ubiquitous survival advantage," the authors wrote in their research review covering a multitude of species. 

"Indeed, the sex difference in longevity may be one of the most robust features of human biology," the researchers said.

Though other species, from roundworms and fruit flies to a spectrum of mammals, show lifespan differences that may favour one sex in certain studies, contradictory studies with different diets, mating patterns or environmental conditions often flip that advantage to the other sex. 

With humans, however, it appears to be all females all the time.

The differences may be due to hormones, perhaps as early as the surge in testosterone during male sexual differentiation in the uterus. 

Longevity may also relate to immune system differences, responses to oxidative stress, mitochondrial fitness or even the fact that men have one X chromosome (and one Y), while women have two X chromosomes, the researchers said.

Evidence of the longer lifespans for women includes the Human Mortality Database, which has complete lifespan tables for men and women from 38 countries that go back as far as 1751 for Sweden and 1816 for France. 

"Given this high data quality, it is impressive that for all 38 countries for every year in the database, female life expectancy at birth exceeds male life expectancy," authors Steven Austad and Kathleen Fischer wrote.

Longer female survival expectancy is seen across the lifespan, at early life (birth to five years old) and at age 50. 

It is also seen at the end of life, where Gerontology Research Group data for the oldest of the old show that women make up 90 percent of the supercentenarians, those who live to 110 years of age or longer, the study pointed out.​