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Neuroscience

Sleep is a neuronal-network matter

Scientists decode the way worms switch between wakefulness and sleep.

How the brain switches between sleep and wakefulness is an open question, but in the worm Caenorhabditis elegans it seems the process occurs passively.

Manuel Zimmer and his colleagues at the Research Institute of Molecular Pathology in Vienna used a new calcium-imaging technology to simultaneously view the activity of most of the worm’s brain cells during a particular stage of larval development. During this stage the creatures are prone to falling asleep — providing oxygen levels remain as low as those in their normal soil environment.

When the scientists lowered oxygen levels, around three-quarters of the neurons became silent. Those not silenced included neurons responsible for monitoring alarming environmental signals such as high oxygen levels, and these caused the animals to awaken when the scientists raised oxygen levels.

This indicates that sleep is an emergent property of neuronal circuits, rather than an activity strictly enforced by specific brain areas, as others have suggested.

More Research Highlights...

Pulsar wind nebula illustration

Curving purple lines in this artist’s impression represent the magnetic field of a neutron star (white sphere) left over from a brilliant supernova. Credit: Salvatore Orlando/INAF-Osservatorio Astronomico di Palermo

Astronomy and astrophysics

X-rays expose a clue to the mystery of the missing neutron star

Astronomers might have spotted the long-sought debris of a famous stellar explosion.
A bone fragment next to a dime

A bone fragment excavated in Southeast Alaska belonged to one of the earliest known domestic dogs in the Americas. Credit: Douglas Levere/University at Buffalo

Genomics

An ancient Alaskan dog’s DNA hints at an epic shared journey

To scientists’ surprise, a 10,000-year-old bone found in an Alaskan cave belonged to a domestic dog — one of the earliest known from the Americas.
Emissions billow from smokestacks at a coal-fired power plant as the sun sets, India.

Black carbon emitted by power plants and other sources in Asia wafts to the Arctic, where the pollution accelerates the melting of ice and snow. Credit: Kuni Takahashi/Bloomberg/Getty

Atmospheric science

Soot from Asia travels express on a highway to the high Arctic

Black carbon from fuel combustion in South Asia bolsters the effects of climate change on northern ice and snow.
Prevotella copri bacteria, computer illustration

The gut bacterium Prevotella copri (artist’s impression) has been linked to a reduction in the health benefits of a diet that skimps on red meat in favour of fish and vegetables. Credit: Kateryna Kon/Science Photo Library

Microbiology

Trying a Mediterranean diet? Gut microbes might sway the outcome

The composition of a person’s microbiome could influence the health effects of swapping steak for vegetables and olive oil.
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