Philippa Kaur

A study conducted in mice suggests certain gut bacteria can regulate motivation to exercise by increasing dopamine levels in the brain during physical activity

Humans

14 December 2022

By Grace Wade
The gut may play a roll in our motivation to exerciseJacob Lund/Alamy
Motivation to exercise may come from the gut in addition to the brain. A study in mice finds that certain gut bacteria can increase the release of dopamine during physical activity, which helps drive motivation.
Though most of us know that exercise comes with many benefits, how much people exercise varies widely, says Christoph Thaiss at the University of Pennsylvania. He and his colleagues wanted to identify physiological factors that may explain this variation.
They collected data from 106 mice on exercise capacity, genetics, gut microbiome composition and more, and fed it to a machine learning model for analysis. The model found that how often mice exercised was most strongly associated with the makeup of their microbiome.Advertisement
In a series of experiments that followed, the researchers found that mice with depleted gut microbes spent about half as much time voluntarily running on a wheel as those with intact microbiomes. What’s more, they had reduced dopamine levels in their brains during physical activity, suggesting they found exercise less rewarding. The team then repeated these experiments in mice that had intact microbiomes but lacked neurons connecting the gut to the brain and found this resulted in the same effects seen in mice with depleted microbiomes. Together, these findings show the gut plays an integral role in motivation for exercise, Thaiss says.
The team also identified molecules produced by certain gut bacteria called fatty acid amides that, when given to mice with depleted microbiomes, restored how often they exercised to levels seen in mice with intact microbiomes. “Surprisingly, the motivation for exercise is not brain-intrinsic but is regulated by the gastrointestinal tract,” says Thaiss.
This isn’t the first time the microbiome has been found to play a role in functions outside our gastrointestinal system. In fact, previous studies have shown that the bacteria in our guts may influence our mood, control blood sugar levels and even protect against inflammation linked to conditions like heart disease and dementia.
However, it is too early to know if these findings in mice are also true for humans, Thaiss says. He and his team are currently conducting a similar trial in people to see whether we have the same gut-to-brain pathway, and if so, whether leveraging it will boost our motivation to exercise.
Journal reference: Nature, DOI: 10.1038/s41586-022-05525-z

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Researchers used MRI scans and an algorithm to measure the stiffness and resilience to pressure of the brain in living people

Humans

14 December 2022

By Karmela Padavic-Callaghan
Brains are surprisingly squishyShutterstock/Teeradej
Though they may look like they are made from rubber, human brains are softer and squishier. Their ability to resist pressure is much less than the polystyrene foam used for packaging, more comparable to that of Jell-O.
Nicholas Bennion at Cardiff University in the UK and his colleagues set out to develop a method for obtaining more accurate measurements of the brain’s physical properties inside living humans. Most of what we know about how brain tissue reacts to instruments touching it during neurosurgery comes from organs that have been cut into or removed and preserved in chemicals, which can affect tissue stiffness and resilience.
The researchers performed MRI scans of people lying face down and then face up to shift the location of the brain in the skull. By analysing this data with a machine learning algorithm, they were able to work out different material characteristics of the brain and tissues that connect it to the skull. They quantified how much the brain collapses when pressed on, how it reacts to being pushed sideways and how springy the connective tissues are.Advertisement
“If you take a brain which hasn’t been preserved in any way, its stiffness is incredibly low, and it breaks apart very easily. And it really is probably a lot softer than most people realise,” says Bennion.
The team found that brain matter can be compressed up to 10 times as easily as polystyrene foam and that its resilience to being pushed sideways is about a thousandth of what it would be if it were made from rubber – its squishiness is comparable to a slab of Jell-O. Bennion says that the algorithm calculated that the tissues connecting the brain to the skull were also fairly soft, possibly to protect the brain from moving too abruptly.
Though researchers have long known that brains are very soft and very fragile, the new study makes that notion precise enough to better inform sensitive surgical procedures, says Ellen Kuhl at Stanford University in California.
The new method, however, may not fully capture the way the brain deforms during motions more violent than shifting positions, such as head trauma in an contact sport or traffic accident, says Krystyn Van Vliet at the Massachusetts Institute of Technology. In these situations, the flow of fluids within the brain can change its material properties.
The team hopes the model can now be used to predict brain shifts that would occur during surgery for each individual patient based on pre-operative MRI scans. This may eliminate the need for inserting and re-inserting instruments into the brain until they hit the correct spot, making procedures less invasive.
Journal reference: Journal of the Royal Society Interface, DOI: 10.1098/rsif.2022.0557

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Researchers used MRI scans and an algorithm to measure the stiffness and resilience to pressure of the brain in living people

Humans

14 December 2022

By Karmela Padavic-Callaghan
Brains are surprisingly squishyShutterstock/Teeradej
Though they may look like they’re made from rubber, human brains are softer and squishier. Their ability to resist pressure is like that of a slab of gelatine, and they break apart more easily than polystyrene foam used for packaging.
Nicholas Bennion at Cardiff University in the UK and his colleagues set out to develop a method for obtaining more accurate measurements of the brain’s physical properties inside living humans. Most of what we know about how brain tissue reacts to instruments touching it during neurosurgery comes from organs that have been cut into or removed and preserved in chemicals, which can affect tissue stiffness and resiliency.
Combining a machine learning algorithm with MRI scans of people lying face down and then face up to shift the location of the brain in the skull, the researchers were able to work out different material characteristics of the brain and tissues that connect it to the skull. They quantified how much the brain collapses when pressed on, how it reacts to being pushed sideways and how springy the connective tissues are.Advertisement
“If you take a brain which hasn’t been preserved in any way, its stiffness is incredibly low, and it breaks apart very easily. And it really is probably a lot softer than most people realise,” says Bennion.
The team found that brain matter collapses up to 10 times more easily than polystyrene foam and that its resilience to being pushed sideways is about a thousandth of what it would be if it were made from rubber – meaning its squishiness is comparable to a slab of gelatine. Bennion says that the algorithm calculated that the tissues connecting the brain to the skull were also fairly soft, possibly to protect the brain from moving too abruptly.
Though researchers have long known that brains are very soft and very fragile, the new study makes that notion precise enough to better inform sensitive surgical procedures, says Ellen Kuhl at Stanford University in California.
The new method, however, may not fully capture the way the brain deforms during motions more violent than shifting positions, such as head trauma in an impact sport or traffic accident, says Krystyn Van Vliet at the Massachusetts Institute of Technology. In these situations, the flow of fluids within the brain can change its material properties.
The team hopes their model can now be used to predict brain shifts that will occur doing surgery for each individual patient based on pre-operative MRI scans. This may eliminate the need for inserting and re-inserting instruments into the brain until they hit the correct spot, making procedures less invasive.
Reference: Journal of the Royal Society Interface, DOI: 10.1098/rsif.2022.0557

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Would your radiation badge work? What would it be like to witness a nuclear bomb blast? The early uncertain days of the UK’s nuclear test programme are poignantly recalled by service veterans in a series of four films at the Plym to Pamlico exhibition

Humans

13 December 2022

By Laura Cooke
A screengrab from the British Nuclear Test Veterans Association nuclear test films, part of the Plym to Pamlico exhibition.British Nuclear Test Veterans Association
Plym to Pamlico
The Royal Engineers Museum, Gillingham, UK
Until 12 March 2023
From flying through mushroom clouds collecting radioactive samples to waking up in a tent covered in aggressive crustaceans, a new series of films is lifting the lid on what it was like to take part in the UK’s nuclear testing programme in the 1950s and 1960s.
Four short films mix animation with images taken during operations from the … More

By Kismat Shrees
The first archaeological survey of the site of Porvenir, where a century-old massacre occurred at the US-Mexico border, has discovered bullets and cartridge casings for US military weapons.
A ballistics analysis has raised new questions about the role of the US Army in the 1918 Porvenir massacre, where Texas Rangers killed 15 unarmed Mexican boys and men. The new evidence collected by David Keller, an archaeologist at Sul Ross State University in Texas, and colleagues suggest the US army could have played a bigger role in the massacre than previously thought.

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Spotlight on plankton, the ocean’s fascinating, bite-sized creaturesEvery night, plankton take a journey to shallower waters to feed, prompting predators to follow in search of a very small, but tasty, snack. These images are taken from a new book, Planktonia, illuminating their daily ascent More

From a bone fragment of a mysterious new species to the latest on cave art, Paul Pettit’s powerful new book shows how science is rewriting the past

Humans

7 December 2022

By Alison George
Upper Palaeolithic art on a replica of the Chauvet cave, south-east FranceAndiA/Alamy
Homo Sapiens Rediscovered
Paul Pettitt (Thames & Hudson)
WHO are we? This fundamental question has always exercised humanity. One way to approach it is to look at our origins and the evolutionary journey we have taken. Today, thanks to powerful new tools, we can look at the lives of our ancestors in unprecedented detail: the meals they ate, their relationships. And through their art and other practices, we can even get hints about their beliefs about the world.
Paul Pettitt, … More