The week’s most astounding developments from the neobiological frontier.

April 21, 2022

How the brain zaps intrusive, unwanted memories

Humans have remarkable capacity for episodic memory—the ability to recall who-what-where-when-why narratives in our heads—an asset, no doubt, that helped our ancestors survive in a cruel, cold world. But we also have the profound capability to actively forget things, which is likely another evolutionary asset, allowing us to shake off bad memories and trauma. Now scientists at the University of Cambridge and Southwest University in Chongqing, China, have uncovered how our brains control such “motivated forgetting.” Imaging the brains of 24 people as they actively suppressed specific memories, the researchers showed that the brain’s anterior cingulate sits sentinel, zapping away bad thoughts before they take hold. When unwanted thoughts begin to emerge in the mind, that brain region signals a rapid top-down inhibition of specific neuronal circuits in the hippocampus, suppressing the memory in the moment and helping us forget it completely over the long run. The Journal of Neuroscience

Synthetic nerves made of artificial neurons

Researchers at Oxford University have developed an artificial nerve composed of a bundle of synthetic, bio-inspired neurons made from hydrogel fibers, fats, and watery nanodrops. The team showed they could create electrical signals with light-driven proton pumps, propagate the impulses down a centimeter or so of artificial axon, and trigger the release of neurotransmitters at its terminal. Synthetic nerves like these might play roles in next-generation implants, soft machines, and computing devices, the researchers write. Nature Chemistry

Encryption protects patient privacy in collaborations

If the phrase “multiparty homomorphic encryption” makes your eyes glaze over, would you believe us if we said it could just be the most important concept you read today? A group at EPFL in Lausanne, Switzerland and the University of Tübingen in Germany have shown this week that this powerful, if arcane, privacy-protecting protocol for distributed computing could be used to train a machine-learning algorithm on larger and larger data sets drawn from multiple institutions without requiring the actual data to be transferred from one to the other. This is important because it will enable discovery without compromising privacy—concerns over which have traditionally stood as a barrier to large, multi-institutional collaborations. Patterns

Do antidepressants improve quality of life?

This result is bound to be controversial: A retrospective study of tens of millions of medical records in the United States found that when compared to people who took no drugs, people who took antidepressant medications did not see significant improvements in their health-related quality of life—a broad measure of one’s perceived physical or mental well-being. Conducted by researchers at King Saud University in Riyadh, Saudi Arabia, the work analyzed self-reported summaries of physical and mental health of people diagnosed with depression from 2005–2016 from the U.S. Medical Expenditures Panel Survey. The researchers say their results show the need to better assess the long-term impact of drugs for depression as well as non-pharmacological interventions, like behavioral modifications, psychotherapy, social support, and education. PLOS ONE

Researchers project rise of malaria with solar geoengineering

The threat of tropical disease outbreaks and pathogens spreading to cooler climates is among the well-known risks of global warming. But attempting to tackle greenhouse gasses through solar geoengineering could paradoxically place a billion more people at risk of malaria in the next 50 years, warn researchers at Georgetown University and the University of Cape Town. Modeling the impact of geoengineering strategies designed to offset global warming out to 2070, the researchers project many places would see increased transmission—particularly low-income settings in sub-Saharan Africa and southern Asia. This in no way slams shut the door on geoengineering as a potential approach to addressing global warming, but the suggestion that it could worsen health outcomes in the Global South should be considered as we implement it in the future. Nature Communications

Portable, low-field MRI tested at the bedside

For people who suffer ischemic strokes, time is the enemy. The longer it takes to clear a clotted blood vessel and restore oxygenating flow to the brain, the worse the damage to the brain. On the other hand, the faster you intervene, say by administering the clot-buster drug tPA, the better the outcome. The problem is you can’t just give people tPA presumptively because if they are having a hemorrhagic stroke, you’ll only make it worse. You need to image the brain first, which takes specialized equipment and time. Now doctors at Yale School of Medicine have demonstrated the feasibility of doing faster bedside imaging using a portable MRI. In a study involving 50 people, they showed an experimental low-field MRI could detect even small occlusion blockages in the brain. Besides potentially shaving precious minutes and saving lives in the United States, the work also sets the stage for increased availability of MRI instruments in low- and middle-income countries. Science

Detecting stress levels in rescue dogs

Veterinarians at Utrecht University in the Netherlands have demonstrated a way to monitor doggie wellness by measuring cortisol levels in the hair of rescue dogs. Quantifying the hair cortisol of 52 canines when they arrived at shelters, again six weeks later, and twice more after they were adopted, the researchers established that when dogs are placed in kennels, they suffer stress. Though more work needs to be done to understand how a dog’s breed affects these levels, their work provides a quantitative new way to measure canine stress and could inform changes to the physical structures or daily routines of shelters to improve the welfare of rescue dogs—and of course make their adoptive owners happier too. Scientific Reports