Science and Medicine

Brain rhythm predicts ability to sleep through a noisy night

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Brain rhythum Study

People who have trouble sleeping in noisy environments often resort to strategies like earplugs or noise-canceling headphones that muffle the sound, but a new study from investigators at Massachusetts General Hospital (MGH) may lead to ways to block disturbing sounds within the brain. The team reports finding a brain-wave pattern, reflecting activity of a key structure, that predicts the ease at which sleep can be disrupted by noise.

“We wanted to investigate what the brain does to promote stable sleep, even in the face of noise, and why some people are better at staying asleep than others,” said Jeffrey Ellenbogen, MD, chief of the MGH Division of Sleep Medicine. “Understanding the tools and techniques the brain naturally uses could help us harness and expand those responses to help stay asleep in noisy environments.”

Upon entering the brain, most sensory information, including sound, passes through a deep-brain structure called the thalamus on its way to the cortex where signals are perceived. Communication between these structures continues during sleep and is reflected by fluctuations in the brain’s electrical field, producing rhythmic patterns detected through electroencephalography (EEG). Typical EEG patterns are used to distinguish stages of sleep, and in the second and third stages, slow brain wave patterns are interspersed with brief, rapid pulses called spindles.

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These crocs were made for chewing?

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When crocodiles tried to be mammals: the Cretaceous crocodilan Pakasuchus kapilimai, complete with complex, mammal-like dentition and an unusually flexible spine, hunts dragonflies on an ancient Tanzanian floodplain.

Paleontologists scouring a river bank in Tanzania have unearthed a previously unknown crocodile from 105 million-year-old, mid-Cretaceous rock in the Great East African Rift System.

The discovery of the relatively lanky, cat-sized animal with mammal-like teeth and a land-based lifestyle supports a growing consensus that crocodiles were once far more diverse than they are today, dominating ecological niches in the Southern Hemisphere during the Cretaceous Period that were filled in the Northern Hemisphere by early mammals.

An international team of researchers led by Patrick O’Connor of Ohio University describes the new animal in the Aug. 5 issue of Nature.

“At first glance, this croc is trying very hard to be a mammal,” O’Connor said. While numerous character traits show the animal is clearly crocodylian, he added, “A number of characteristics of this new species—including a reduction in its total number of teeth and a dentition specialized into ones similar to canines, premolars and occluding molars—are very similar to features that were critical during the course of mammalian evolution from the Mesozoic into the Cenozoic.”

The researchers have dubbed the new animal Pakasuchus kapilimai. Paka is Ki-Swahili for cat, in reference to the animal’s short, low skull with slicing, molar-like teeth, and souchos is from the ancient Greek for crocodile. The species name kapilimai is in honour of the late professor Saidi Kapilima of the University of Dar es Salaam, a key contributor to the NSF-supported Rukwa Rift Basin Project that led the discovery.

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