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Pupils reveal the absence of visual imagination

Aphantasia, a lack of visual imagination ability, can be detected through measuring pupil dilation, according to a new study published in eLife.

Psychology researchers found that the pupils of people with aphantasia did not respond when asked to imagine dark and light objects, while those without aphantasia did. They studied the pupillary reflexes of 42 participants who had self-reported as having a visual imagination, and 18 participants self-reporting aphantasia, by fitting them with glasses to track their eye movements and pupil sizes.

Participants were exposed to bright or dark shapes against a grey background, which induced pupillary constriction in response to bright shapes, and dilation in response to dark shapes.

They were then asked to imagine those same shapes, and researchers found that the pupils of participants without aphantasia still constricted and dilated appropriately, a pupillary response that was larger in those self-reporting greater imagery vividness.

But the individuals with aphantasia’s pupillary responses didn’t significantly differ in response to imagined dark versus imagined bright objects.

Gastric inflammation: how bacterial infection causes tissue changes

Helicobacter pylori bacteria infect about half the world’s population. In the stomach, infection can lead to gastric inflammation and increases the risk of developing stomach cancer.

New research has discovered the characteristic changes which occur inside the gastric glands during an H. pylori infection, using mouse models and special organ-like tissue microstructures known as organoids.

Helicobacter infection causes the release of pro-inflammatory substances that deactivate a mechanism which usually restricts cell division in healthy stomach tissue to protect it against cancerous changes, and instead enables cells to grow in an uncontrolled manner.

The study was published in Nature Communications.

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Stomach tissue infected with Helicobacter bacteria. Dividing cells are depicted in green, cell nuclei in blue. Credit: Charité/Michael Sigal

Cannabis poisoning of pets increased significantly in US and Canada

Pets exposed to cannabis, most often by ingestion, may experience symptoms of cannabis poisoning – also known as cannabis-induced toxicosis – with varying degrees of severity.

Now, a survey of 251 veterinarians in the US and Canada has revealed that cases of cannabis poisoning among pets have increased in North America since Canada’s 2018 legalisation. Conducted in 2021, the survey included questions about cannabis poisoning cases encountered by participants over several previous years.

The study, published in PLoS ONE, suggests this could be explained by increased cannabis use, but increased reporting may have contributed as well.

Unattended ingestion of cannabis edibles was the most frequent cause of poisoning, and was most frequently seen in dogs, but cases were also reported in cats, iguanas, ferrets, horses and cockatoos.

With use of cannabis products continuing to rise, the biomedical scientists call for additional research into the effects of cannabis on pets to help inform veterinary efforts and policies to keep pets healthy.

A new kind of 3D printing

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A boat figurine produced by a new 3D printing process that makes it possible to print an object within a volume of resin –like an action figure floating in the center of a block of jelly – rather than having to build the object layer by layer. Credit: Dan Congreve.

Stanford University engineers in the US have developed a new kind of 3D printing that doesn’t rely on building objects up layer-by-layer, and removes the need for the support structures typically required for creating complex designs.

In this new technique, described in a paper published in Nature, the printed object is fully supported by a thick resin – imagine an action figure floating in the centre of a block of jelly – so it can be added to from any angle.

It works by focusing a red laser into a gelatinous resin that hardens when exposed to blue light. When this laser hits one of the tiny nanomaterials scattered throughout the resin it’s converted into blue light at that precise focal point, curing the resin.

This uses a method called triplet fusion upconversion, where, with the right molecules in close proximity to each other, the researchers can create a chain of energy transfers that turn low-energy red photons into high-energy blue ones.

Protected areas don’t always boost species numbers

Protected areas such as national parks have a “mixed impact” on wildlife, according to the largest ever global study of their effects, published recently in Nature.

The study focused on waterbirds, examining the impact of 1,500 protected areas (in 68 countries) on more than 27,000 waterbird populations by comparing waterbird population trends before and after protected areas were established.

The conservation scientists found that, while many protected areas are working well, others are failing to have a positive effect. Areas that are managed with species in mind are more likely to benefit populations, and larger areas are more beneficial than smaller ones.

Calls to conserve 30% of the Earth’s surface by 2030 are gathering pace, but the researchers argue that targets need to be set for the quality of protected areas, not just the quantity of them.

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A Pied Avocet. Credit: Robert Blanken

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