Tuesday, June 6, 2017

Highlights and new discoveries in Neuroscience (May 2017)

In the latest edition of this monthly digest series, you can learn about bioengineered retinas for the visually impaired, how TV consumption is linked to developmental issues in children, and why our brain cells may prevent us from burning fat when we diet.


Our brains predict events in fast-forward

What happens when you look up and see a ball headed toward you? Without even thinking about it, you flinch. That might be because our brains are constantly living our lives in fast-forward, playing out the action in our head before it happens.

Humans have to navigate, and respond to, an environment that is always changing. Our brain compensates for this by constantly making predictions about what’s going to happen, says Mattias Ekman, a researcher at Radboud University Nijmegen in the Netherlands. We’ve known this for a while, but these predictions are usually associative. An example: if you see a hamburger, your brain might predict that there will be fries nearby. In a study published today in the journal Nature Communications, Ekman and other scientists focused instead on how the brain predicts motion. So they used brain scans to track what happened as participants observed a moving dot.

First, 29 volunteers looked at a white dot the size of a ping-pong ball. The dot went from left to right and then reversed directions. The volunteers watched the dot for about five minutes while scientists scanned their brains with ultra-fast fMRI. This way, the researchers know what pattern of brain activity was activated in the visual cortex while they watched the dot.

After these five minutes, the researchers showed only the beginning of the sequence to the volunteers. Here, the scans showed that the brain “autocompletes” the full sequence — and it does it at twice the rate of the actual event. So if a dot took two seconds to go across the screen, the brain predicted the entire sequence in one second. “You’re actually already trying to predict what’s going to happen,” says Ekman. “These predictions are hypothetical, so in a way you’re trying to generate new memories that match the future.”

Of course, events in the real world are a lot more complex than a dot moving across the screen, and that’s the biggest limitation of the study. “It’s difficult to transfer this into the real world because there objects aren’t deterministic and, for example, a car can take a turn,” says Ekman. “So then the question is, is the brain still able to do these more complex predictions?” The next step is to figure out how well the results hold up in real-world scenarios, and what exactly is going on when someone says to look up because a ball is headed our way.

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Why our brain cells may prevent us from burning fat when we diet

A study carried out in mice may help explain why dieting can be an inefficient way to lose weight: key brain cells act as a trigger to prevent us burning calories when food is scarce. Mice share a number of important biological and physiological similarities with humans and so are a useful model for studying how our bodies work.

“Weight loss strategies are often inefficient because the body works like a thermostat and couples the amount of calories we burn to the amount of calories we eat,” says Dr ClĂ©mence Blouet from the Metabolic Research Laboratories at University of Cambridge. “When we eat less, our body compensates and burns fewer calories, which makes losing weight harder. We know that the brain must regulate this caloric thermostat, but how it adjusts calorie burning to the amount of food we’ve eaten has been something of a mystery.”

The researchers tested the role of a group of neurons in a brain region known as the hypothalamus. These ‘agouti-related neuropeptide’ (AGRP) neurons are known for their major role in the regulation of appetite: when activated, they make us eat, but when fully inhibited they can lead to almost complete anorexia. The researchers demonstrated that AGRP neurons are key contributors to the caloric thermostat that regulates our weight, regulating how many calories we burn. The findings suggest that when activated, these neurons make us hungry and drive us to eat – but when there is no food available, they act to spare energy, limiting the number of calories that we burn and hence our weight loss.

“While this mechanism may have evolved to help us cope with famine, nowadays most people only encounter such a situation when they are deliberately dieting to lose weight,” says the study's first author, Dr Luke Burke. “This study could help in the design of new or improved therapies in future to help reduce overeating and obesity. Until then, best solution for people to lose weight – at least for those who are only moderately overweight – is a combination of exercise and a moderate reduction in caloric intake.”

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Miscellaneous

A new study by researchers from the Salk Institute and UC San Diego reports that microglia (the "immune cells" of the brain) may play a role in a diverse array of neurodegenerative and psychiatric illnesses. (Science)

Researchers from the University of Toronto report that dream dysfunctions and REM sleep disorders may be warning signs of neurodegenerative diseases up to 15 years before other symptoms appear. (via NeuroscienceNews)

Those who find it hard to cope with uncertainty over possible future threats could have an unusually large striatum, a new Dartmouth study reports. (Emotion)

The visual cortex, the human brain’s vision-processing center that was previously thought to mature and stabilize in the first few years of life, actually continues to develop until sometime in the late 30s or early 40s, a McMaster neuroscientist and her colleagues have found. (Journal of Neuroscience)

A team of neuroscientists from Emory University’s Silvio O. Conte Center for Oxytocin and Social Cognition has discovered a key connection between areas of the adult female prairie vole’s brain reward system that promotes the emergence of pair bonds. Results from this study could help efforts to improve social abilities in human disorders with impaired social function, such as autism. (Nature via NeuroscienceNews)

Researchers from the University of Oxford bioengineered a retina from soft synthetic (hydrogels) and biological tissue (cell membrnaes). The development could revolutionize the bionic implant industry, offering hope for visually impaired people. Designed like a camera, the cells act as pixels, detecting and reacting to light to create a grey scale image. Lead researcher Vanessa Restrepo-Schild said: ‘The synthetic material can generate electrical signals, which stimulate the neurons at the back of our eye just like the original retina.’ Miss Restrepo-Schild has filed a patent for the technology and the next phase of the work will see the Oxford team expand the replica’s function to include recognising different colours. Working with a much larger replica, the team will test the material’s ability to recognise different colours and potentially even shapes and symbols. Looking further ahead the research will expand to include animal testing and then a series of clinical trials in humans. (Scientific Reports)


Salk Institute scientists, building on earlier work that identified a gene pathway triggered by running, have discovered how to fully activate that pathway in sedentary mice with a chemical compound, mimicking the beneficial effects of exercise, including increased fat burning and stamina. Although the lab’s studies have been in mice, pharmaceutical companies are interested in using the research to develop clinical trials for humans. (via NeuroscienceNews)

Surmain, a century old drug originally developed to treat African sleeping sickness, shows promise for treating symptoms of autism, according to researchers from UC San Diego. (via NeuroscienceNews)

Researchers from the University of Bonn report low doses of THC can help restore memory and reverse some of the effects of brain aging in mice. The findings could open new avenues for treating dementia and other neurodegenerative diseases. (Nature Medicine)

A new study from Indiana University places the appearance of modern human-like cognition at the emergence of Homo erectus 1.8 million years ago, 600,000 years before the appearance of Neanderthals. (Nature Human Behavior)

According to researchers of Emery University, dads with toddler daughters are more responsive to their child’s needs than fathers with toddler sons. Fathers of toddlers also sang more often to their daughters and spoke more openly about emotions, including sadness, possibly because they are more accepting of girls’ feelings than boys’, according to the study. Fathers of sons engaged in more rough-and-tumble play and used more achievement-related language (e.g., words such as proud, win and top) when talking to their sons. Fathers of daughters used more analytical language (e.g., words such as all, below and much), which has been linked to future academic success. (via NeuroscienceNews)

The human brain is much better than previously thought at discovering and avoiding disease, a new study led by researchers at Karolinska Institutet in Sweden reports. Our sense of vision and smell alone are enough to make us aware that someone has a disease even before it breaks out. And not only aware – we also act upon the information and avoid sick people. (PNAS)

Watching more than three hours of television a day is associated with poorer language skills for 11-year-olds, according to a new international study. Children who watch less than 3 hrs of TV a day when they start primary school are also more likely to communicate their ideas effectively when they move on to secondary school. “The television effect was a very interesting finding and we saw it had a bigger impact for the children with lower language skills, but made little difference to those who had had higher levels of language,” says lead researcher James Law, Professor of Speech and Language Sciences at Newcastle University’s School of Education. (Clinical Development via NeuroscienceNews)